Abstract 3105: PDCM Finder: An open global cancer research platform for patient-derived cancer models

PDCM Finder (https://cancermodels.org) is a new portal that aggregates patient-derived models (xenografts, cell lines and organoids) from 27 academic and commercial providers, enables users to search and compare over 6000 models and associated molecular data, and connects users with model providers to facilitate collaboration among researchers.

Users can search for models of interest by either (1) exploring molecular data summaries for models of specific cancer types, or (2) using the intuitive search and faceted filtering options of the web user interface or (3) access resource database via REST API to run their own analysis. The data includes gene expression, gene mutation, copy number alteration, cytogenetics, patient treatment and drug dosing studies. We link external resources like publication platforms and cancer specific annotation tools enabling exploration and prioritization of PDCM variation data (COSMIC, CIViC, OncoMX, OpenCRAVAT).

In addition to exploring PDCM metadata and data, the portal enables users to validate their PDX models against PDX MI standard, get a FAIRness score of the model of interest, explore originating resource data processing protocols, training materials and contact the model supplier/provider.

PDCM Finder builds on the success of the PDX Finder resource (PMID:30535239). Critical PDCM attributes, such as diagnosis, drug names and genes, are harmonized and integrated into a cohesive ontological model based on the PDX Minimal information standard (PDX MI, PMID: 29092942). PDX MI has become established in the community for data exchange, adopted by the PDX providers, consortia and informatics tools integrating PDX data. We are working with the community on the PDCM Minimal Information standard in an effort to make PDCM datasets adhere to the FAIR data principles. We are driving the development of and promoting the use of descriptive standards to facilitate data interoperability and promote global sharing of models. We provide expertise and software components to support several worldwide consortia including PDXNet, PDMR and EurOPDX. PDCM Finder is freely available under an Apache 2.0 license (https://github.com/PDCMFinder). This work is supported by NCI U24 CA204781 01, U24 CA253539, and R01 CA089713. We welcome feedback on the resource and are looking for participants for usability studies - please get in touch if interested.

Citation Format: Zinaida Perova, Csaba Halmagyi, Alex Follette, Mauricio Martinez, Federico Lopez-Gomez, Jeremy Mason, Abayomi Mosaku, Nathalie Conte, Ross Thorne, Steven Neuhauser, Dale Begley, Debra Krupke, Terrence Meehan, Carol Bult, Helen Parkinson. PDCM Finder: An open global cancer research platform for patient-derived cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3105.

The EurOPDX Data Portal: an open platform for patient-derived cancer xenograft data sharing and visualization

Background

Patient-derived xenografts (PDX) mice models play an important role in preclinical trials and personalized medicine. Sharing data on the models is highly valuable for numerous reasons – ethical, economical, research cross validation etc. The EurOPDX Consortium was established 8 years ago to share such information and avoid duplicating efforts in developing new PDX mice models and unify approaches to support preclinical research. EurOPDX Data Portal is the unified data sharing platform adopted by the Consortium.

Main body

In this paper we describe the main features of the EurOPDX Data Portal (https://dataportal.europdx.eu/), its architecture and possible utilization by researchers who look for PDX mice models for their research. The Portal offers a catalogue of European models accessible on a cooperative basis. The models are searchable by metadata, and a detailed view provides molecular profiles (gene expression, mutation, copy number alteration) and treatment studies. The Portal displays the data in multiple tools (PDX Finder, cBioPortal, and GenomeCruzer in future), which are populated from a common database displaying strictly mutually consistent views.

(Short) Conclusion

EurOPDX Data Portal is an entry point to the EurOPDX Research Infrastructure offering PDX mice models for collaborative research, (meta)data describing their features and deep molecular data analysis according to users’ interests.

Abstract 3212: PDX Finder: Largest global catalog of patient tumor derived xenograft models

Patient-derived tumor xenograft (PDX) models are a critical oncology platform for cancer research, drug development and personalized medicine. Because of the heterogeneous nature of PDX repositories, finding models of interest is a challenge. The Jackson Laboratory and EMBL-EBI are developing PDX Finder, the world's largest open PDX database containing phenomic information of over 2900 models (www.pdxfinder.org, †). In support of this initiative, we developed the PDX Minimal Information standard (PDX-MI) which defines the minimal necessary metadata required to describe models (††). Within PDX Finder, critical attributes like diagnosis, drug names or genes are harmonized into a cohesive ontological data model based on PDX-MI. An intuitive, faceted search interface allows users to select models based on clinical/PDX attributes, tumor markers, dataset availability and/or drug dosing results. We provide PDX, patient, drug and molecular data details pages where all available information can be browsed and downloaded. To further facilitate users' model selection, we link key external resources like publication platforms and cancer specific annotation tools, enabling exploration and prioritisation of PDX variation data (COSMIC, CivicDb, OpenCRAVAT). Links to originating resource protocols and contact information are provided, facilitating data understanding and further collaboration.

Alongside database development activities, PDX Finder has undertaken activities to tackle areas of standards and tool development, data integration and outreach. PDX Finder provides key expertise and software components to support several worldwide consortia including PDXNet, PDMR and EurOPDX. We are driving the development of, and promoting the use of descriptive standards to facilitate data interoperability and promote global sharing of models. Our standard has become established in the community for data exchange, adopted by PDX providers, consortia, and informatic tools integrating PDX data. It has been re-used by different initiatives in the context of data collection and data modelling allowing adherence to the FAIR data principles - Findability, Accessibility, Interoperability and Reusability. PDX Finder is increasing awareness of PDX models, facilitating data integration, and enabling international collaboration, maximising the investment in, and translational capabilities of these important models of human cancer.

PDX Finder is freely available under an Apache 2 license (github.com/pdxfinder). Work supported by NCI U24 CA204781 01, R01 CA089713 and the European Molecular Biology Laboratory.

† Conte et al, 2019. PDX Finder: A Portal for Patient-Derived tumor Xenograft Model Discovery. NAR, 2019 Jan.†† Meehan, Conte et al, 2017. PDX-MI: Minimal Information for Patient-Derived Tumor Xenograft Models. Cancer Res. 2017 Nov.PDXNet: www.pdxnetwork.org, PDMR: pdmr.cancer.gov, EUROPDX: www.europdx.eu

Citation Format: Nathalie Conte, Csaba Halmagyi, Abayomi Mosaku, Jeremy C. Mason, Alex W. Follette, Ross Thorne, Steven Neuhauser, Dale Begley, Debbie M. Krupke, Helen Parkinson, Terrence Meehan, Carol Bult. PDX Finder: Largest global catalog of patient tumor derived xenograft models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3212.

Mental health nurses' views about antipsychotic medication side effects

WHAT IS KNOWN ON THE SUBJECT?: The only previous quantitative study that examined nurses' use of assessment tools to identify antipsychotic medication side effects found that about 25% of mental health nurses were using assessment tools. No previous studies have examined factors that influence the manner in which mental health nurses assess antipsychotic medication side effects. WHAT THIS PAPER ADDS TO EXISTING KNOWLEDGE?: One-third of the respondents were not aware of any antipsychotic medication side-effect assessment tool, and only one-quarter were currently using an assessment tool. 'Service responsibility' was significantly associated with ongoing use of antipsychotic medication assessment tools, indicating that respondents with more positive attitudes to their service were more likely to continue using antipsychotic medication assessment tools. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: The low level of awareness and use of antipsychotic medication side-effect assessment tools indicates that nursing educational institutions should incorporate more detail about these tools in course content, and emphasize in particular the benefits that result from the use of these tools in clinical practice. Service processes contributed significantly to the use of antipsychotic medication assessment tools, which indicates that managers need to foster workplace cultures that promote routine use of these tools.

ABSTRACT

Introduction Limited evidence suggests that only a minority of mental health nurses regularly use standardized assessment tools to assess antipsychotic medication side effects, but the factors that contribute to the non-routine use of these tools remain unknown. Aim To examine Australian mental health nurses' awareness of, and attitudes towards, side-effect assessment tools, and also identify factors the influence the use of these tools. Methods A cross-sectional survey was undertaken through distributing an online questionnaire via email to members of the Australian College of Mental Health Nurses. Completed questionnaires were received from 171 respondents. Linear regression was used to examine the relationship between the 'service responsibility' and 'personal confidence' scale scores, and awareness, previous use and ongoing use of antipsychotic medication assessment tools. Results Only one-quarter of the respondents (26.5%) were currently using an assessment tool. 'Service responsibility' was significantly associated with ongoing use of antipsychotic medication assessment tools (Β = 3.26; 95% CI 0.83-5.69). 'Personal confidence' did not influence the ongoing use of assessment tools (Β = -0.05; 95% CI -1.06-1.50). Implications for clinical practice Stakeholders can incorporate 'service responsibility' processes to foster increased use of assessment tools, which may enhance the identification antipsychotic medication side effects and improve the quality of care for service users.

Functional Analysis of the Cooled Rat Testis

Direct cooling of the testis results in the depletion of most germ cells in vivo. Germ cell-depleted testes are now commonly used to investigate spermatogenic regeneration and can serve as recipients for germ cell transplantation. The present study explored the effects of cooling rat testes on the depletion of endogenous germ cells, spermatogenic regeneration, and Sertoli cell function. Adult rat testes were cooled with iced Ringer's solution for 60 minutes, which results in the initiation of apoptotic germ cell loss within 8 hours. Pachytene spermatocytes at stages XII-I were the cells most sensitive to cooling. In 46%-67% of seminiferous tubule cross-sections, only Sertoli cells remained in the cooled testes 3-10 weeks after treatment. Germ cell loss was accompanied by a significant decrease in circulating inhibin B and an increase in follicle-stimulating hormone concentrations, which indicated a change in Sertoli cell function. Quantitative analysis of mRNA expression associated with apoptotic signals showed no significant uniform changes among the cooled testes, although some individuals had a distinct up-regulation of FAS mRNA at 24 hours. Attempts to use the cooled testes as recipient testes for mouse-to-rat germ cell transplantation were undertaken, but none of the mouse germ cells transplanted into the testes 15-34 days after cooling appeared to have undergone spermatogenesis 64-92 days after transplantation. These data suggest that modifications to Sertoli cell function resulting from testicular cooling create an environment that is unable to support spermatogenesis by donor germ cells.

Dehiscence of the posterior and superior semicircular canal presenting in pregnancy

OBJECTIVE

We present an interesting case of superior and posterior semicircular canal dehiscence in pregnancy.

METHOD

We present a case report and a review of the world literature concerning semicircular canal dehiscence.

CASE REPORT

A 34-year-old woman presented with sound and pressure induced vertigo at 22 weeks gestation. A thinly sliced computed tomography (CT) scan of the petrous temporal bones viewed with coronal reconstructions was performed post-partum. This showed the presence of both left superior canal and posterior canal dehiscence.

CONCLUSION

To our knowledge this is the first reported case of semicircular canal dehiscence in pregnancy. The diagnosis of semicircular canal dehiscence should be suspected in pregnant patients with sound induced vertigo.

Successful outcome of cochlear implantation in a patient with superficial siderosis

OBJECTIVE

To present the management of a rare case of progressive bilateral sensorineural hearing loss in a patient with superficial siderosis secondary to a cavernoma.

METHOD

A case report and a review of the literature concerning superficial siderosis.

RESULTS

The patient benefited significantly from a cochlear implantation.

CONCLUSIONS

Careful assessment and adequate counselling is necessary to determine the best approach to hearing rehabilitation in patients with superficial siderosis of the central nervous system. Cochlear implantation in patients with superficial siderosis is controversial due to the retrocochlear origin of the hearing loss and, although the case presented had a successful outcome, the results might deteriorate with time.

Introduction of routine outcome measures: staff reactions and issues for consideration

The aim of this study was to explore clinician reactions to (i) the introduction of routine outcome measures and (ii) the utility of outcomes data in clinical practice. Focus group discussions (n = 34) were conducted with mental health staff (n = 324) at approximately 8 months post implementation of routine outcome measures. A semi-structured interview schedule was used to collect data on two key issues; reactions to the introduction of outcome measures and factors influencing the utility of outcomes data in clinical practice. Data from the discussion groups were analysed using content analysis to isolate emerging themes. While the majority of participants endorsed the collection and utilization of outcomes data, many raised questions about the merits of the initiative. Ambivalence, competing work demands, lack of support from senior medical staff, questionable evidence to support the use of outcome measures, and fear of how outcomes data might be used emerged as key issues. At 8 months post implementation a significant number of clinical staff remained ambivalent about the benefits of outcome measurement and had not engaged in the process. The shift to a service model driven by outcomes and case-mix data will take time and resources to achieve. Implications for nursing staff are discussed.

Aggressive behaviour in the high-secure forensic setting: the perceptions of patients

Twenty-seven patients undergoing treatment in a high-secure forensic facility participated in focus group interviews to elicit their perceptions of (1) the factors leading to aggressive behaviour; and (2) strategies to reduce the risk of such behaviour. The focus group interviews were audiotaped, transcribed and analysed using content analysis. The participants identified that a combination of patient, staff and environmental factors contributed to violence in the study wards. The cause of aggressive behaviour centred around five major themes: the environment; empty days; staff interactions; medication issues; and patient-centred factors. Potential strategies identified by patients to reduce aggressive behaviour included: early intervention; the provision of meaningful activities to reduce boredom; separation of acutely disturbed patients; improved staff attitudes; implementation of effective justice procedures; and a patient advocate to mediate during times of conflict. Findings suggested that social and organizational factors need to be addressed to change the punitive subculture inherent in forensic psychiatric facilities, and to ensure a balance between security and effective therapy.

Cerebrospinal fluid glucose levels and sensorineural hearing loss in bacterial meningitis

BACKGROUND

Low cerebrospinal fluid (CSF) glucose levels have been associated with sensorineural hearing loss (SNHL) in bacterial meningitis but systematic investigations are lacking.

PATIENTS AND METHODS

A retrospective case control study was conducted comparing CSF glucose levels in 47 cases with and 145 controls without SNHL following bacterial meningitis.

RESULTS

The mean CSF glucose level (standard deviation [SD]) was 1.3 mmol/l (1.2) in cases and 2.5 mmol/l (1.6) in controls (p < 0.001). The difference between the groups was significant for Streptococcus pneumoniae and Haemophilus influenzae but not for Neisseria meningitidis infection. It was independent of the delay of treatment if this was greater than 12 h. This delay was significantly longer in cases compared to controls.

CONCLUSION

In bacterial meningitis other than that caused by N. meningitidis and independent of the duration of symptoms prior to diagnosis, CSF glucose levels were significantly lower in patients developing a SNHL compared to controls.

The impact of relocation on elderly patients with mental illness

Twenty-three elderly patients with long-term mental illness were relocated from a large tertiary mental health facility to two extended care units (ECUs) in their district of origin. The patients were assessed on measures of functioning, aggression and agitation at 6 weeks pre-relocation, and again at 6 weeks and 6 months post-relocation. The impact of relocation on the group proved to be less dramatic than findings reported in the literature. The adverse affects of relocation were likely to have been offset by the preparation and planning undertaken prior to relocation, and the support provided to staff and patients in the period following relocation. The findings have implications for nursing staff involved in the relocation of people with mental illness between wards within a hospital or from one hospital to another.

Support for condom availability and needle exchange programs among Massachusetts adults, 1997

This study was conducted to determine whether demographic factors, variables related to HIV risk status, or personal attitudes predicted public support for condom availability programs in high schools and needle exchange programs. Data for these analyses were collected from the 1997 Massachusetts Behavioral Risk Factor Surveillance System (BRFSS) among adults aged 18-64. Overall, 79% of Massachusetts adults aged 18-64 supported condom availability programs, and 60% supported needle exchange programs. Younger age was the strongest demographic predictor of support for condom availability, and higher socioeconomic status was the strongest predictor of support for needle exchange programs. Support for both programs was weakly associated with personal HIV risk status but strongly associated with positive attitudes toward teaching about HIV in schools and advising sexually active teens to use condoms. Our data suggest that there is broad-based public support for implementation of condom availability and needle exchange programs as tools for HIV prevention.

Immobilization of cesium-137 and uranium in contaminated sediments using soil amendments

Batch and dynamic leaching methods were used to evaluate the effectiveness of hydroxyapatite (HA), illite, and zeolite, alone and in combination, as soil additives for reducing the migration of cesium-137 (137Cs+) and uranium (U) from contaminated sediments. Amendment treatments ranging from 0 to 50 g kg(-1) were added to the sediment and equilibrated in 0.001 M CaCl2. After equilibration, the treatment supernatants were analyzed for 137Cs+, U, PO4, and other metals. The residual sediments were then extracted overnight using one of the following: 1.0 M NH4Cl, 0.5 M CaCl2, or the Toxicity Characteristic Leaching Procedure (TCLP) extractant. Cesium was strongly sorbed to the contaminated sediments, presumably due to interlayer fixation within native illitic clays. In fact, 137Cs+ was below detection limits in the initial equilibration solutions, the CaCl2 extract, and the TCLP solution, regardless of amendment. Extractants selective for interlayer cations (1.0 M NH4Cl) were necessary to extract measurable levels of 137Cs+. Addition of illitic clays further reduced Cs+ extractability, even when subjected to the aggressive extractants. Zeolite, however, was ineffective in reducing Cs+ mobility when subjected to the aggressive extractants. Hydroxyapatite was less effective than illite at reducing NH4+-extractable Cs+. Hydroxyapatite, and mixtures of HA with illite or zeolite, were highly effective in reducing U extractability in both batch and leaching tests. Uranium immobilization by HA was rapid with similar final U concentrations observed for equilibration times ranging from 1 h to 30 d. The current results demonstrate the effectiveness of soil amendments in reducing the mobility of U and Cs+, which makes in-place immobilization an effective remediation alternative.

Trans- and cis-DNA adduct concentration in epidermis from mouse and rat skin treated ex vivo with benzo[a]pyrene diol epoxide and its corresponding chlorohydrin

Benzo[a]pyrene diol epoxide, a metabolite of benzo[a]pyrene (BaP), and chlorohydrin, the reaction product of chloride and the epoxide, form in vitro the same trans- and cis-stereoisomeric DNA adducts, but in different proportions. In this study, we asked whether the DNA adduct concentration can be kept the same by applying the appropriate dose of (+/-)-7r,8t-dihydroxy-9t,10t-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE)and (+/-)-7r,8t,9t-trihydroxy-10c-chloro-7,8,9,10-tetrahydrobenzo[a]pyrene (trans-BPDCH) to rodent skin and whether the DNA adducts formed differ only in their trans- and cis-stereoisomerism. Skin from C57Bl6 mice, spontaneous hypertension rats (SHR) and Sprague-Dawley (SD) rats was treated ex vivo immediately after the death of the animals with anti-BPDE and its corresponding bay region chlorohydrin trans-BPDCH and the epidermis was analyzed for DNA adducts 1h after the application. We found that adduct formation at the exocyclic amino groups of deoxyguanosine and deoxyadenosine in epidermal DNA followed a linear dose-response within 6--100 nmol/cm(2) with both chemicals. In order to achieve the same adduct concentration in mouse, spontaneous hypertension rat (SHR), and Sprague-Dawley (SD) rat skin, respectively, a 37-, 23- and 10-fold lower dose of anti-BPDE than of trans-BPDCH had to be applied. The order of 2'-deoxyguanosine (dGuo) adduct concentration with anti-BPDE was similar to what has been reported, but the order with trans-BPDCH was (+)-cis-BPDE-N(2)-dGuo adduct>(+)-trans-BPDE-N(2)-dGuo=(-)-trans-BPDE-N(2)-dGuo>(-)-cis-BPDE-N(2)-dGuo in mouse skin. Irrespective of species or strain, a significantly higher proportion of cis-adducts was obtained after treatment with trans-BPDCH than after treatment with anti-BPDE. Therefore, DNA adduct concentration can be kept the same by applying the appropriate dose of anti-BPDE and trans-BPDCH to rodent skin and the DNA adducts formed differ only in their trans- and cis-stereoisomerism.

Inhibins, activins and follistatin: actions on the testis

While the early studies of the inhibins, activins and follistatins concentrated on their role as endocrine regulators of FSH secretion, recent data has emphasized the local actions of the activins and follistatin. Inhibin, through its capacity to suppress FSH secretion can modulate numerous processes within the testis. However, to date, evidence to support a local role for inhibin is limited. In contrast, activin and its binding protein follistatin are produced by a large number of cell-types within the testis raising the possibility of a range of paracrine and autocrine actions. These include the modulation of androgen production, influence on the proliferation of Sertoli cells and germ cells as well as the capacity to influence the structural and functional features of mitochondria within germ cells. Some of these actions are carefully controlled in a temporal relationship during the development of testicular function in the rat in which there is no separation in time between birth and the onset of spermatogenesis. Given the range of actions of activin in different cell-types, recognition of systems that are designed to modulate its actions are crucial in enhancing our understanding of how these many roles can be compartmentalized.

Developmental regulation of the bcl-2 family during spermatogenesis: insights into the sterility of bcl-w-/- male mice

Expression of bcl-w, a close relative of bcl-2 is essential for male fertility in mice. Although the initial wave of spermatogenesis in bcl-w -/- mice proceeds normally until 3-4 weeks of age, adults fail to produce sperm. To clarify why bcl-w is essential for adult but not juvenile spermatogenesis, we investigated the expression pattern of eight bcl-2 family members. We found that both the level and pattern of expression varied in different cell types during juvenile and adult spermatogenesis. Anti-apoptotic genes bcl-w, bcl-2 and bcl-xL were all expressed in spermatogonia during juvenile spermatogenesis, but only bcl-w was detected in spermatogonia of adult mice. A similar shift was evident in Sertoli cells. This developmental regulation may co-ordinate physiological germ cell apoptosis in wild type mice and account for the time of onset for pathological germ cell apoptosis in bcl-w -/- animals.

The use of the Liverpool University Neuroleptic Side-Effect Rating Scale (LUNSERS) in clinical practice

Forty-four mental health clients completed the Liverpool University Neuroleptic Side-Effect Rating Scale (LUNSERS)--a self-rating scale to assess the prevalence and intensity of neuroleptic side-effects. In the month prior to the study, 50% of the clients surveyed had experienced more than half of the side-effects outlined on the 41-item scale. A prevalence profile allowed us to rank the frequency of individual side-effects across the sample. Some side-effects such as 'difficulty concentrating', 'difficulty remembering', 'tiredness' and 'restlessness' were experienced by most of the clients in the study while 'unusual skin marks', 'difficulty passing water', 'rashes' were experienced by a few. A prevalence profile may be a useful guide in developing strategies for managing side-effects more effectively in small groups of clients. In addition, the use of the LUNSERS in clinical practice would enable case managers to establish baseline measures for individual clients and evaluate changes in medication and other non-medical strategies for reducing unwanted side-effects. The identification and assessment of antipsychotic side-effects is an important area for client and professional carer education.

Enhancing case managers' skills in the assessment and management of antipsychotic medication side-effects

OBJECTIVE

Our goal was to reduce the prevalence of antipsychotic medication side-effects by providing a short-term training program on the assessment and management of side-effects to case managers.

METHOD

Forty-four patients in receipt of community-based mental health services were allocated to comparison (n = 20) and intervention (n = 24) groups based on the health service district in which they resided. While case managers working with the intervention group attended a short-term training program to improve their assessment and management of neuroleptic side-effects, case managers providing services to the comparison group received no additional training. Side-effects were assessed pre- and postintervention using the Liverpool University Neuroleptic Side-effect Rating Scale (LUNSERS).

RESULTS

A reduction in the overall prevalence of side-effects in both groups was observed, however, only those patients in the intervention group reported a statistically significant reduction in mean side-effect scores between the pre- and postmeasures (Wilcoxon Matched Pairs Signed-ranks Test, z = -2.8411, two-tailed, p < 0.01). In addition, qualitative data collected during the second survey revealed that patients in the intervention group had acquired some positive management strategies for dealing with unwanted side-effects. The strategies were elicited from eight different patients distributed across six of the 12 case managers who took part in the training program.

CONCLUSIONS

Training cases managers in the assessment and management of side-effects may help to reduce their impact on the lives of people prescribed neuroleptic medication.

Cloning and characterization of a 72-kDa inositol-polyphosphate 5-phosphatase localized to the Golgi network

The inositol-polyphosphate 5-phosphatase enzyme family removes the 5-position phosphate from both inositol phosphate and phosphoinositide signaling molecules. We have cloned and characterized a novel 5-phosphatase, which demonstrates a restricted substrate specificity and tissue expression. The 3.9-kb cDNA predicts for a 72-kDa protein with an N-terminal proline rich domain, a central 5-phosphatase domain, and a C-terminal CAAX motif. The 3. 9-kilobase mRNA showed a restricted expression but was abundant in testis and brain. Antibodies against the sequence detected a 72-kDa protein in the testis in the detergent-insoluble fraction. Indirect immunofluorescence of the Tera-1 cell line using anti-peptide antibodies to the 72-kDa 5-phosphatase demonstrated that the enzyme is predominantly located to the Golgi. Expression of green fluorescent protein-tagged 72-kDa 5-phosphatase in COS-7 cells revealed that the enzyme localized predominantly to the Golgi, mediated by the N-terminal proline-rich domain, but not the C-terminal CAAX motif. In vitro, the protein inserted into microsomal membranes on the cytoplasmic face of the membrane. Immunoprecipitated recombinant 72-kDa 5-phosphatase hydrolyzed phosphatidylinositol 3,4,5-trisphosphate and phosphatidylinositol 3, 5-bisphosphate, forming phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3-phosphate, respectively. We propose that the novel 5-phosphatase hydrolyzes phosphatidylinositol 3,4, 5-trisphosphate and phosphatidylinositol 3,5-bisphosphate on the cytoplasmic Golgi membrane and thereby may regulate Golgi-vesicular trafficking.

Regulation of germ cell and Sertoli cell development by activin, follistatin, and FSH

We have demonstrated a role for activin A, follistatin, and FSH in male germ cell differentiation at the time when spermatogonial stem cells and committed spermatogonia first appear in the developing testis. Testis fragments from 3-day-old rats were cultured for 1 or 3 days with various combinations of these factors, incubated with bromodeoxyuridine (BrdU) to label proliferating cells, and then processed for stereological analysis and detection of BrdU incorporation. Gonocyte numbers were significantly elevated in cultures treated with activin, while the combination of FSH and the activin antagonist, follistatin, increased the proportion of spermatogonia in the germ cell population after 3 days. All fragment groups treated with FSH contained a significantly higher proportion of proliferating Sertoli cells, while activin and follistatin each reduced Sertoli cell division. In situ hybridization and immunohistochemistry on normal rat testes demonstrated that gonocytes, but not spermatogonia, contain the activin beta(A) subunit mRNA and protein. In contrast, gonocytes first expressed follistatin mRNA and protein at 3 days after birth, concordant with the transition of gonocytes to spermatogonia. Collectively, these data demonstrate that germ cells have the potential to regulate their own maturation through production of endogenous activin A and follistatin. Sertoli cells were observed to produce the activin/inhibin beta(A) subunit, the inhibin alpha subunit, and follistatin, demonstrating that these cells have the potential to regulate germ cell maturation as well as their own development. These findings indicate that local regulation of activin bioactivity may underpin the coordinated development of germ cells and somatic cells at the onset of spermatogenesis.

The roles of inhibin and related peptides in gonadal function

Inhibin A and B are dimeric proteins capable of suppressing FSH both in vitro and in vivo. The principal form in the male is inhibin B which is produced in the testis and circulates to inhibit pituitary FSH secretion. Activin A, B and AB are dimeric proteins that share the same beta subunits with the inhibins but, in contrast, stimulate FSH secretion. Although activin A circulates, castration does not lead to a decrease in serum concentrations, indicating that the testis is not the major source of activin A. In the circulation, the activins are bound to a structurally unrelated binding protein, follistatin, that neutralizes the biological actions of these proteins. The subunits of the inhibins/activins as well as follistatin are also produced locally within the pituitary and their levels can be modulated by testosterone and gonadotrophin releasing hormone as well as by autocrine mechanisms. Consequently, the output of FSH is dependent of the balance between local processes and the circulating feedback exerted by testosterone and inhibin. There is increasing data to support the local gonadal production of not only inhibin but also activin and follistatin by both germ cells and somatic cells such as the Sertoli cells. Evidence is accumulating to support the concept that these proteins exert local regulatory mechanisms in the testis.

Development and validation of clinical indicators for mental health nursing practice

A national study was undertaken in Australia to develop and validate a set of clinical indicators for mental health nursing. Using survey and action research procedures, the indicators were developed in two stages. During stage one, focus group interviews involving 39 nurses were conducted at national conferences in Australia and New Zealand in order to provide a pool of indicator statements. A Delphi survey of an Australian sample of mental health nurses (n = 33) was then conducted to refine the indicators. In stage two, the refined indicators were tested and validated in selected clinical settings. A total of 1751 mental health nurses employed at 14 sites were involved in the second stage of the study. The resulting data were used to establish the set of national indicators that the Australian and New Zealand College of Mental Health Nurses will use in practice accreditation and benchmarking.

Patients' perceptions of seclusion: a qualitative investigation

Twelve patients receiving acute in-patient psychiatric care in Queensland, Australia, participated in semi-structured interviews to elicit their perceptions of seclusion. All respondents had experienced time in seclusion within the 7 days prior to interview. Interviews were audiotaped, transcribed and analysed using content analysis. Five major themes emerged: use of seclusion, emotional impact, sensory deprivation, maintaining control and staff-patient interaction. The prevailing negativity towards seclusion underscores the need for ongoing critical review of its use. In particular, the relationship between patient responses to seclusion and the circumstances in which seclusion takes place requires greater consideration. Interventions such as providing information to patients about seclusion, increased interaction with patients during seclusion, attention to privacy and effective debriefing following seclusion may help to reduce the emotional impact of the practice.

Application of morphometric techniques to postnatal rat testes in organ culture: insights into testis growth

The extent of Sertoli cell proliferation during fetal and neonatal development determines the final adult testis size and potential for sperm output. To gain further knowledge of the factors that regulate Sertoli cell proliferation, the present study used a new approach to analyse changes in morphology and proliferation in the postnatal testis by combining organ culture with morphometric analysis. Fragments of rat testes from days 0 to 10 postpartum were cultured in contact with DMEM for 6 h or 72 h and fixed. The effects of ovine follicle-stimulating hormone (FSH) and activin were studied in an additional 72-h organ culture experiment using day 9 testes. Bromodeoxyuridine (BrdU) was added for the last 6 h of culture to mark proliferating cells. Two-microm sections of the fragments were analysed for morphological changes of the seminiferous cords, and the proportion of BrdU-labelled Sertoli and germ cells was determined. Assessment of 6-h samples revealed growth characteristics consistent with those observed in vivo during days 1-10 of postnatal development. From day 2 onwards, the volume fraction of seminiferous cords began to increase, while significant growth in cross-sectional area of the cords occurred only after day 6. In these culture conditions, germ cell proliferation and testicular architecture was consistent with that expected for the age of the tissue at time of explant. The proportion of dividing Sertoli cells declined from 15-20% at days 0-4 postpartum to below % at day 10 postpartum in the 6-h culture, and it was low or abolished in the 3-day culture at all time points. Activin and FSH together, but not singly, stimulated Sertoli cell proliferation in the 72-h culture. This paper presents a new approach to analysis of in vitro testis development. The combination of fragment culture and stereological analysis permits rigorous and detailed assessment of developmental changes in the postnatal testis.

Factors influencing nurse-patient interaction in the acute psychiatric setting: an exploratory investigation

Nurse-patient interaction in acute psychiatric in-patient facilities has been the subject of much discussion in the literature and remains a contentious issue. How and why nurses interact with patients in the acute care setting requires definition within the current dynamic environment of mental health service provision. Factors which impact on the manner in which nurses care for patients also require investigation. This article presents the findings of a collaborative research study that investigates factors that influence nurse-patient interaction in the acute psychiatric setting. Ten nurses on the study ward were given opportunity, through semi-structured interviews, to outline and describe the factors perceived to influence nurse-patient interaction. Factors identified as influencing interaction included the ward environment, something always comes up, nurses' attributes, patient factors, instrumental support and focus of nursing. Issues which emerged from the study provide managers and clinical nurses with an opportunity for generating new possibilities for nurse-patient interaction. However, these issues must be addressed in a sensitive way that takes into account the complex and dynamic nature of acute care settings.

Absconding behaviour: an exploratory investigation in an acute inpatient unit

OBJECTIVE

The aim of this study is to identify patient and environmental characteristics associated with absconding behaviour, and to gain an understanding of the behaviour from the patients' perspective.

METHOD

A prospective analysis of 77 consecutive incidents of absent-without-leave (AWOL) behaviour (n = 51 patients) was undertaken to develop a profile of patient and environmental characteristics associated with absconding behaviour. In addition, semi-structured interviews were carried out with a subsample of 14 patients within 24 h of returning to hospital from being AWOL.

RESULTS

Those who absconded were male (58%), under 40 years of age (74%), admitted involuntarily (78%), and had a diagnosis of schizophrenia (42%). One-third of all AWOL incidents resulted from repeated absconding by the same individuals. The first 7 days post admission was a high-risk period for absconding behaviour. Issues raised in the interviews with patients identified a number of situational and environmental factors which are likely to increase the risk of absconding.

CONCLUSIONS

Situational and environmental factors are more likely than patient characteristics to be predictive of absconding behaviour.

Mutations in a gene encoding a new oxygen-regulated photoreceptor protein cause dominant retinitis pigmentosa

The autosomal dominant retinitis pigmentosa (RP) locus, designated RP1, has been mapped through linkage studies to a 4-cM interval at 8q11-13. Here we describe a new photoreceptor-specific gene that maps in this interval and whose expression is modulated by retinal oxygen levels in vivo. This gene consists of at least 4 exons that encode a predicted protein of 2,156 amino acids. A nonsense mutation at codon 677 of this gene is present in approximately 3% of cases of dominant RP in North America. We also detected two deletion mutations that cause frameshifts and introduce premature termination codons in three other families with dominant RP. Our data suggest that mutations in this gene cause dominant RP, and that the encoded protein has an important but unknown role in photoreceptor biology.

Ultrasonographic monitoring of artificially stimulated ejaculation in three rhinoceros species (Ceratotherium simum, Diceros bicornis, Rhinoceros unicornus)

Manual massage of the penis and rectal electroejaculation methods have been minimally effective for collecting semen from the rhinoceros. These two methods for stimulating ejaculation were evaluated by rectal ultrasonography. One individual each of three rhinoceros species (Ceratotherium simum simum, Rhinoceros unicornis and Diceros bicornis) was stimulated by manual massage of the penis and two black rhinoceroses (Diceros bicornis) were electroejaculated. On ultrasonography, neither manual massage nor rectal electroejaculation affected the accessory glands. The pelvic urethra remained empty during manual massage of unconditioned animals; however, this area was filled before commencement of massage of conditioned animals. The pelvic urethra also filled during electroejaculation. Semen accumulated in the pelvic urethra during pauses between electrical stimulations and was moved distally into the penile urethra by rectal and penile massage. The volumes of seminal fluid recovered from electroejaculation in this study exceeded previously reported attempts. This study demonstrated the potential of transrectal imaging for improving the recovery of semen by these methods.

Boarding house life for people with mental illness: an exploratory study

The present study explored residents' perceptions of life in boarding houses within the Central Sydney Area Health Service. A purposeful sample of 14 people with a mental illness participated in semistructured interviews. The transcribed interviews were analysed for lifestyle issues to increase understanding of the factors that impact on quality of life from the consumers' perspective. It was encouraging to find that basic needs were being met, but it would appear that there is considerable room for improvement in quality of life for this vulnerable group of people. The findings of the present study should prove valuable for policy makers and health professionals who provide services to people with mental illness resident in boarding houses.

Apoptosis regulator bcl-w is essential for spermatogenesis but appears otherwise redundant

Proteins of the Bcl-2 family are important regulators of apoptosis in many tissues of the embryo and adult. The recently isolated bcl-w gene encodes a pro-survival member of the Bcl-2 family, which is widely expressed. To explore its physiological role, we have inactivated the bcl-w gene in the mouse by homologous recombination. Mice that lack Bcl-w were viable, healthy, and normal in appearance. Most tissues exhibited typical histology, and hematopoiesis was unaffected, presumably due to redundant function with other pro-survival family members. Although female reproductive function was normal, the males were infertile. The testes developed normally, and the initial, prepubertal wave of spermatogenesis was largely unaffected. The seminiferous tubules of adult males, however, were disorganized, contained numerous apoptotic cells, and produced no mature sperm. Both Sertoli cells and germ cells of all types were reduced in number, the most mature germ cells being the most severely depleted. The bcl-w-/- mouse provides a unique model of failed spermatogenesis in the adult that may be relevant to some cases of human male sterility.

Weight changes during clozapine treatment

OBJECTIVE

The aim of this study was to assess the prevalence and magnitude of weight changes pre- and post-clozapine and to explore the ability of demographic and clinical factors to predict weight gain at 12 months post-clozapine.

METHOD

Weight changes in a sample of 51 patients were assessed at 3 months pre-clozapine, at baseline, and at 3 and 12 months post-clozapine. In addition, demographic data and information concerning changes in appetite and activity level at 3 months was gathered and used to predict weight gain at 12 months.

RESULTS

Seventy percent of patients gained an average of 7.5 kg (10.6% increase in baseline body weight) over the 12-month period. Although post-clozapine weight gain for the total group was significant at 12 months, weight gain for the female subsample (n = 16) did not reach significance at either the 3 or 12 month assessments. The only factors associated with marked weight gain (> 15% increase) at 12 months were increased food intake early in treatment and having gained weight at 3 months.

CONCLUSION

Clozapine treatment was found to be associated with significant weight gain in patients prescribed clozapine, especially male patients. Considering the long-term health risks associated with excess weight gain, health professionals can play an important role in educating clients about the potential for weight gain with clozapine treatment.

Synthesis and characterization of bay region halohydrins derived from Benzo[a]pyrene diol epoxide and their role as intermediates in halide-catalyzed cis adduct formation

The bay region epoxide of benzo[a]pyrene (anti-BPDE) alkylates DNA to form adducts with >98% trans stereochemistry. Halide ions catalyze this reaction; however, this pathway is characterized by the formation of adducts with altered cis stereochemistry. Bay region halohydrins are possible intermediates in these reactions, but are too unstable to be isolated from aqueous solutions. However, we successfully synthesized halohydrins in tetrahydrofuran (THF) by treatment of anti-BPDE with the corresponding lithium halide salt in the presence of acetic acid. Absorbance and CD spectroscopy clearly indicated the formation of chloro-, bromo-, and iodohydrins. The structure and stereochemistry of the chlorohydrin was established by NMR. Chloride addition is exclusively at the benzylic position of the epoxide, and the stereochemistry of the C-9 and -10 positions is trans. The long-wavelength absorbance band in the chloro-, bromo-, and iodohydrin is red-shifted 7, 13, and 22 nm, respectively, relative to the hydrolysis product of anti-BPDE. The ellipticity of the same absorbance band in CD spectra of enantiomerically pure halohydrins is opposite in sign compared to that of the corresponding anti-BPDE enantiomer. The relative stability of these derivatives is chlorohydrin > bromohydrin > iodohydrin. The chloro- and bromohydrins were isolated, but the iodohydrin decomposed during this manipulation. The addition of 500 mM chloride decreased the hydrolysis rate of the chlorohydrin 4-fold in 50% THF/buffer. Direct evidence for the transient formation of the iodohydrin in aqueous buffer/acetone mixtures was obtained by absorbance spectroscopy. At 1 M chloride, bromide, and iodide, alkylation of deoxyadenosine by anti-BPDE in aqueous buffer yields 85, 91, and 92% cis adducts, respectively. In the absence of halide, alkylation of deoxyadenosine in buffer by anti-BPDE, the chlorohydrin, and the bromohydrin yields 32, 65, and 83% cis adducts, respectively.

Arrests and incarceration of injection drug users for syringe possession in Massachusetts: implications for HIV prevention

Multiperson use of syringes is a major risk behavior responsible for the spread of HIV-1 among injection drug users (IDUs). In Massachusetts, two laws regulate syringes: one is a prescription law prohibiting possession or purchase of syringes without a prescription, and the other makes it illegal to possess drug paraphernalia, including syringes. In 1993, Massachusetts amended the prescription law to permit the establishment of syringe exchange programs in two cities. Enrolled participants are allowed to possess syringes anywhere in the state, and about 5% of the estimated 40,000 IDUs in Massachusetts are program participants. To understand how HIV prevention efforts with active IDUs may be constrained by the enforcement of laws criminalizing possession of syringes after the amendment in the law, we reviewed data from multiple sources to assess the number of arrests for syringe possession in 10 large cities in Massachusetts to evaluate incarceration rates and lengths of sentences for those convicted of syringe possession and to estimate costs of incarceration for those convicted of syringe possession. At least 824 persons were arrested for syringe possession in 1995. In examining the data on convictions, we found that 417 persons were convicted in 1994 of syringe possession in the absence of other serious charges, and of these, 41.0% were sentenced to incarceration. The average sentence imposed was 5 months (range, 3 days-2 years). Assuming that those convicted serve about two thirds of their sentences, the cost of incarceration was estimated at $1,140,183 excluding costs for arrest, pretrial detention, prosecution, or other costs of enforcement. Costs for incarcerating persons convicted of both syringe and drug possession were not included; the total cost of incarceration of persons convicted of possession of a syringe, with or without other major charges, is probably considerably higher. Had these funds been allocated to pay for drug treatment, 1629 admissions to drug detoxification programs could have been purchased. Retaining drug paraphernalia and syringe prescription laws in Massachusetts may contribute to HIV transmission. These findings support the recommendation of the American Medical Association to modify drug paraphernalia laws so that IDUs can purchase and possess syringes without a prescription.

Neuroleptic malignant syndrome: an assessment of registered psychiatric nurses' knowledge

Neuroleptic Malignant Syndrome (NMS) is a potentially fatal complication of neuroleptic use and is frequently underdiagnosed by medical and nursing staff. The current project was undertaken to assess the knowledge registered psychiatric nurses (RPN) have of the signs, symptoms and interventions to be initiated in cases of NMS. A total of 126 RPN employed in a large tertiary inpatient facility and community mental health centre responded to a self-completed questionnaire. The results indicate that while the RPN in the study's sample demonstrated adequate knowledge of NMS, there was evidence to suggest that these RPN may actually lack confidence in their ability to identify and initiate appropriate interventions in suspected cases of NMS. Although RPN employed in the rehabilitation and psychogeriatric areas of the hospital had more years of experience in the mental health field, their overall knowledge of NMS was significantly lower than that of RPN employed in other clinical settings (F = 3.35; d.f. = 5119; P = 0.007). The findings underscore the importance of ongoing education for RPN employed within clinical mental health settings.

Council playgrounds in New South Wales: compliance with safety guidelines

Despite initiatives to improve the safety of play environments, playground-related injuries continue to be a major public health problem. Efforts to address playground safety in New South Wales were consolidated during 1994 through the Kidsafe Playground Safety Project. In stage 1 of the project (described here), 240 council playgrounds were assessed to determine the extent to which playground equipment complied with safety guidelines. On-site inspection of the selected playgrounds provided data on 862 separate pieces of playground equipment. Of the 723 pieces requiring undersurfacing, less than half (45.4 per cent) had the recommended type of undersurfacing while only 42 of those pieces had undersurfacing to the recommended depth. However, when the fall height of equipment was considered in addition to the undersurfacing guidelines, only 13 (1.8 per cent) of the 723 pieces of equipment simultaneously satisfied all of the safety guidelines. Regrettably, none of the 240 council playgrounds assessed complied fully with the key safety guidelines. The results underscore the need for a collaborative effort on the part of local government, Kidsafe and health promotion and regional public health units to ensure that council playgrounds in New South Wales comply with recommended safety guidelines.

Crisis intervention workers in New South Wales: knowledge, skills, qualities and preparation

Ninety-five mental health workers employed by 13 randomly selected crisis intervention and extended hours teams in NSW responded to a questionnaire designed to elicit information concerning the perceived competencies required for crisis intervention. The findings reported and underscore the need for specialized knowledge and skills to address the problems presented by mentally ill clients in crisis. Assessment of suicide risk, being able to work as part of a team, and knowledge of crisis intervention strategies were perceived as the most important competencies required. It is suggested that these competencies are gained through initial induction programmes, 'on-the-job' experience, and clinical supervision rather than previous experience in the mental health field. The lists of competencies provided will be of interest to those involved in the development of induction and continuing education programmes for crisis intervention workers and in the selection of staff for positions in crisis intervention.

Benzo[a]pyrene diol epoxide-DNA cis adduct formation through a trans chlorohydrin intermediate

Alkylation of DNA by 7r,8t-dihydroxy,9t,10t-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE) forms mainly trans adducts (with respect to the C-9/10 positions). We recently described a halide-catalyzed pathway that preferentially generates cis adducts and now report that the trans chlorohydrin of anti-BPDE (trans-BPDCH) is an intermediate in the chloride-catalyzed reaction. trans-BPDCH was synthesized, and both it and anti-BPDE were reacted with deoxyadenosine as a model DNA nucleophile. The stereochemistry and yields of deoxyadenosine adducts were determined as a function of chloride concentration. In the absence of salt, the fraction of cis adducts obtained from anti-BPDE and trans-BPDCH are 0.33 and 0.67, respectively. Adding sodium chloride increases the fraction of cis adducts (and consequently decreases the fraction of trans adducts), with the midpoint of the increase for both substrates at approximately 35-40 mM chloride. The chloride-dependent curves for BPDE and BPDCH converge at 1 M chloride, where the fraction of cis adducts is 0.88. Chloride also increases the total yield of cis adducts with either substrate, whereas the yield of trans adducts from the chlorohydrin is not significantly changed. These results support a mechanism by which chloride ion undergoes nucleophilic addition to the benzylic C-10 position of anti-BPDE. This generates a trans halohydrin that alkylates DNA with inversion of configuration to form a cis adduct. This pathway may have biological significance because chlorohydrins could form in serum or in cells with relatively high intracellular concentrations of chloride.

The use of behavioural mapping in a study of seclusion

As part of a larger study into the use of seclusion we set out to examine some of the antecedents that led to patients being secluded in one locked psychiatric ward. Behavioural mapping was used to chart the location of incidents that resulted in seclusion. Incidents were observed in several ward areas but most of these occurred in the day room and the dining room. This finding enabled us to question the ward policy of confining patients to these areas to facilitate nursing observation and management. The policy may have contributed to the number of disturbances by limiting personal space for patients. Literature on body buffer zones, crowding and territoriality is used to clarify and interpret the findings.

The effect of sodium ion concentration on intrastrand base-pairing in single-stranded DNA

The salt-induced formation of duplex structure (primarily hairpin loops) in denatured calf thymus DNA was monitored by measuring the decrease in absorbance at 260 nm as a function of increasing sodium ion concentration. It was found that this process was noncooperative and could be accurately described by the mass-action expression for the reversible formation of a binary complex: single strand (coil) + free sodium ion <==> hairpin (with associated sodium ion). The equilibrium constant for the transition was found to be 6 (M Na+)-1. The extrapolated absorbance at infinite salt concentration represents 11% hyperchromicity, which is one third of the hyperchromicity of denatured DNA in the absence of salt (36%).

Alar cartilage haematoma

We present a previously undescribed site of a subperichondrial haematoma--the alar cartilage. Two children presenting acutely, following trauma, with the clinical appearance of a 'blueberry' within the nasal vestibule are described. We recommend early surgical drainage of this lesion, as delay in definitive treatment may give rise to a cosmetic deformity.

Chloride ions catalyze the formation of cis adducts in the binding of anti-benzo[a]pyrene diol epoxide to nucleic acids

The alkylation of DNA by racemic 7r,8t-dihydroxy-9t,10t-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE) exhibits a strong preference for formation of trans adducts between the N2 deoxyguanosine alkylation site and the (+)-enantiomer of anti-BPDE. In the presence of 10 mM buffer with no added salt, 98% of the adducts formed with native calf thymus DNA result from trans opening of the epoxide ring. The strong selectivity for trans adduct formation obtained with duplex DNA at low salt concentration is found to a lesser degree with poly(G) but is nearly absent with dAMP. When DNA adducts are formed in 10 mM MgCl2 or 1 M NaCl, the proportion of cis adducts increases to approximately 7 and approximately 26%, respectively. At low salt, 10 mM MgCl2, and 1 M NaCl, deoxyguanosine adducts are approximately 1%, 6%, and 24% cis, whereas deoxyadenosine adducts are approximately 11%, 14%, and 37% cis, respectively. NaCl also increases the proportion of cis adducts formed with poly(G) and dAMP. It is proposed that the increase in cis-adduct formation due to salt results from SN1 attack of chloride ion on the BPDE carbocation, forming a trans chlorohydrin, followed by SN2 attack of DNA.

Halide-catalyzed cis product formation in the hydrolysis of anti-benzo[a]pyrene diol epoxide and its alkylation of poly(A)

The carcinogen 7-r,8-t-dihydroxy-9-t,10-t-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene (anti-BPDE) forms diastereomeric cis and trans products in its reactions with nucleic acids and water (adducts and tetrols, respectively). The effects of salts, buffers, and DNA on the hydrolysis product ratio were tested. Halide ions increase the cis-tetrol/trans-tetrol ratio, with the order of effectiveness being I > Br > Cl >> F. No cation effect was apparent. Non-halide salts of strong acids increase the ratio to a small degree. Buffers decrease the ratio, with phosphate being more effective than cacodylate. DNA also reduces the ratio, with denatured DNA being more potent than native DNA. Halide ions appear to catalyze cis-tetrol formation via trans halohydrin intermediates. At the lowest halide concentrations which significantly raise the product ratio, and at all levels of chloride ion, the rate of anti-BPDE hydrolysis is not greatly increased, indicating that the halide ions are reacting primarily with the BPDE carbocation formed in the rate-determining step. At higher concentrations, iodide ion and, to a lesser degree, bromide ion significantly accelerate hydrolysis, indicating that BPDE undergoes SN2 attack by these ions. Chloride ion was also found to increase the proportion of cis adducts formed between anti-BPDE and poly(A). The cis adduct/trans adduct ratio was quadrupled by 0.5 M NaCl. This suggests that chlorohydrins can be intermediates in the alkylation of nucleic acids by epoxides of polycyclic aromatic hydrocarbons.

Synthesis and properties of an oligodeoxynucleotide modified with a pyrene derivative at the 5'-phosphate

The synthesis of an oligonucleotide (ODN) modified with pyrene (pyr) on the 5'-phosphate is described. The ODN and pyrene are joined through a linker composed of four methylene groups. Modification of the oligonucleotide was effected via condensation of the 2-cyanoethyl N,N-diisopropylphosphoramidite of 4-(1-pyrenyl)butanol (pyr-m4OPAm, 2) with the 5'-OH of an ODN. This derivative is suitable for incorporation into automated solid-phase DNA synthesis and was attached to the 5' terminus of the DNA chain through a phosphodiester linkage. The properties of the 5'-(pyr-m4)d(T)15 (3) and the duplex it formed with d(A)15 were investigated by fluorescence and absorbance spectroscopy. The pyrene fluorescence in the modified duplex was quenched 96.3% relative to an identical concentration of free 4-(1-pyrenyl)butanol. The ultraviolet spectrum of the 5'-(pyr-m4)-d(T)15 and 5'-(pyr-m4)-d(T)15-d-(A)15 modified duplex, in the 320-360-nm region, was red-shifted 6 nm relative to the free 4-(1-pyrenyl)-butanol. The Tm values of the unmodified and modified duplexes at 0.1 M NaCl were 34.9 and 41.9 degrees C, respectively. The pyrene-induced stabilization corresponds to a free energy change (delta delta G degrees) of -2.6 kcal/mol.