IMPLEMENTATION OF A SCHOOL-BASED HIV PREVENTION CURRICULUM FOLLOWING NATIONAL DISSEMINATION IN NYANZA PROVINCE, KENYA.

BACKGROUND: Primary School Action for Better Health (PSABH) became the national HIV prevention curriculum of Kenya in 2005. OBJECTIVE: To examined implementation of PSABH and student risk behaviour s. SETTING: Muhuru, a rural division of Nyanza Province. SUBJECTS: One thousand one hundred and forty six students aged 9-21 years from six primary schools in Muhuru. OUTCOME MEASURES: Anonymous surveys were administered to assess students'exposure to PSABH curriculum components, sexual activity, condom use, and self-efficacy related to engaging in lower risk behaviours. RESULTS: The six schools implementing PSABH were not implementing the full curriculum. Fifty-five percent of males and 44% of females reported a history of sexual activity. For females, condom self-efficacy was related to lower risk behaviour, while HIV education during pastoral instruction was associated with higher risk. Boys who reported higher self-efficacy and learning about abstinence strategies engaged in lower risk behaviour , while exposure to HIV education in assemblies and communication with relatives about HIV was associated with higher risk. CONCLUSION: Previous studies documented benefits of PSABH. However, it is unclear how effective the curriculum is after national scale-up. In this community, PSABH was implemented at a low level, with some curriculum components associated with higher risk behaviour, calling into question how PSABH is being delivered. Future studies should examine effective strategies for ongoing support, monitoring, and evaluation. Successfully disseminating evidence-based prevention strategies could reduce HIV incidence and the burden on healthcare providers struggling to care for people living with HIV/AIDS.

Understanding genetic toxicity through data mining: the process of building knowledge by integrating multiple genetic toxicity databases.

ABSTRACT Genetic toxicity data from various sources were integrated into a rigorously designed database using the ToxML schema. The public database sources include the U.S. Food and Drug Administration (FDA) submission data from approved new drug applications, food contact notifications, generally recognized as safe food ingredients, and chemicals from the NTP and CCRIS databases. The data from public sources were then combined with data from private industry according to ToxML criteria. The resulting "integrated" database, enriched in pharmaceuticals, was used for data mining analysis. Structural features describing the database were used to differentiate the chemical spaces of drugs/candidates, food ingredients, and industrial chemicals. In general, structures for drugs/candidates and food ingredients are associated with lower frequencies of mutagenicity and clastogenicity, whereas industrial chemicals as a group contain a much higher proportion of positives. Structural features were selected to analyze endpoint outcomes of the genetic toxicity studies. Although most of the well-known genotoxic carcinogenic alerts were identified, some discrepancies from the classic Ashby-Tennant alerts were observed. Using these influential features as the independent variables, the results of four types of genotoxicity studies were correlated. High Pearson correlations were found between the results of Salmonella mutagenicity and mouse lymphoma assay testing as well as those from in vitro chromosome aberration studies. This paper demonstrates the usefulness of representing a chemical by its structural features and the use of these features to profile a battery of tests rather than relying on a single toxicity test of a given chemical. This paper presents data mining/profiling methods applied in a weight-of-evidence approach to assess potential for genetic toxicity, and to guide the development of intelligent testing strategies.

An in silico expert system for the identification of eye irritants.

This report describes development of an in silico, expert rule-based method for the classification of chemicals into irritants or non-irritants to eye, as defined by the Draize test. This method was developed to screen data-poor cosmetic ingredient chemicals for eye irritancy potential, which is based upon exclusion rules of five physicochemical properties - molecular weight (MW), hydrophobicity (log P), number of hydrogen bond donors (HBD), number of hydrogen bond acceptors (HBA) and polarizability (Pol). These rules were developed using the ADMET Predictor software and a dataset of 917 eye irritant chemicals. The dataset was divided into 826 (90%) chemicals used for training set and 91 (10%) chemicals used for external validation set (every 10th chemical sorted by molecular weight). The sensitivity of these rules for the training and validation sets was 72.3% and 71.4%, respectively. These rules were also validated for their specificity using an external validation set of 2011 non-irritant chemicals to the eye. The specificity for this validation set was revealed as 77.3%. This method facilitates rapid screening and prioritization of data poor chemicals that are unlikely to be tested for eye irritancy in the Draize test.

Transformation of BALB/c-3T3 cells: I. Investigation of experimental parameters that influence detection of spontaneous transformation.

The frequency of spontaneous morphological transformation is an important variable in measuring chemical-induced transformation in BALB/c-3T3 clone A-31-1-13 cell cultures. Data from 110 experiments, which included benzo[a]pyrene control groups and other chemical treatment groups, were analyzed for factors that influenced spontaneous transformation. Spontaneous transformants demonstrated a continuum of morphological variants (type I, II, and III foci) that fit a normal distribution if converted to log10. The magnitude of transformation depended on the ampule of cryopreserved cells and the serum lot. Although the average frequency was approximately 0.71 x 10(-6) (type III foci/cell that survived and proliferated to confluence), the absolute number of foci/vessel increased in proportion to the surface area of the culture vessel. Thus, the frequency of spontaneous transformation was directly related to the cumulative number of mitoses that occurred in forming the contact-inhibited monolayer. These data are consistent with a hypothesis that spontaneous transformation in BALB/c-3T3 cells is a mutational event or some other single-step phenomenon.

Transformation of BALB/c-3T3 cells: II. Investigation of experimental parameters that influence detection of benzo[a]pyrene-induced transformation.

Benzo[a]pyrene (BaP) induced significant morphological transformation of clone A31-1-13 BALB/c-3T3 cells without exogenous activation. Therefore, BaP was selected as a model to determine the internal consistency of detection of chemical-induced transformation. BaP induced a continuum of type I-III foci of different sizes, and the ratio of type I-III to type III foci/vessel was usually about 2-fold. The major finding was that BaP induced highly significant transformation responses, and the magnitude of these responses were inversely correlated with the cytotoxicity of the treatment doses. Thus, the induction of BaP-induced transformation behaved as though it was caused by a mutational event. Variability among responses were shown to depend on the serum lot and the cryopreserved ampule of cells. In addition, experiments with low spontaneous transformation responses had an impaired ability to detect BaP; however, experiments with high or normal spontaneous responses had a normal ability to detect BaP. Because the expression of BaP-induced transformation depended on both the cytotoxicity of the treatment and the cumulative number of mitoses, the frequency of BaP-induced transformation should be reported as the number of foci/vessel, but not expressed as the number of foci/viable cell surviving the chemical treatment. These conclusions are important because the same 110 experiments described in this report were also used to evaluate the transformation responses of many different carcinogenic and noncarcinogenic chemicals. These data are being reported separately.

Transformation of BALB/c-3T3 cells: III. Development of a co-culture clonal survival assay for quantification of chemical cytotoxicity in high-density cell cultures.

A co-culture clonal survival assay was developed to measure the cytotoxicity of test chemical treatments to BALB/c-3T3 cells because the standard clonal survival assay using 200 wild type (WT) cells frequently overestimates chemical cytotoxicity when compared with identical treatment doses in high-density cultures. The assay used co-cultures of 3.2 x 10(4) WT cells, the same seeding density used in the transformation assay, and 200 ouabain resistant (OUAr) cells. After a 48-hr test chemical treatment, co-cultured cells were fed with culture medium containing 4 mM ouabain. The test chemical was cytotoxic to an equal percentage of WT and OUAr cells. Ouabain treatments killed the remaining WT cells. Thus, OUAr cells surviving the test chemical treatment measured the relative cloning efficiency (RCE) of all treated cells in the high-density cell co-culture. The co-culture assay succeeded because metabolic cooperation at the OUAr locus was not detected in BALB/c-3T3 cells. Five chemicals induced comparable cytotoxic responses in both assays, including actinomycin D, 5-bromo-2'-deoxyuridine, N'-methyl-N-nitro-N'-nitrosoguanidine, dimethyl sulfoxide and sodium chloride. In contrast, chemical cytotoxic responses detected in the standard and co-culture assays differed by > or = 10-fold for 11-aminoundecanoic acid, benzo[a]pyrene, cytosine arabinoside, and 3-methyl-cholanthrene and differed by > 2-fold for 2-acetylaminofluorene and dimethylnitrosamine. Detection of 11-aminoundecanoic acid-induced transformation was shown to be dependent on selecting treatment doses from the co-culture assay data. Thus, this method permits more accurate assessment of both chemical-induced cytotoxicity and transformation.

Transformation of BALB/c-3T3 cells: IV. Rank-ordered potency of 24 chemical responses detected in a sensitive new assay procedure.

This report introduces an improved method of detecting chemical-induced morphological transformation of A-31-1-13 BALB/c-3T3 cells. The new procedure uses an increased target cell population to assess chemical-induced damage by increasing the initial seeding density and by delaying the initiation time of chemical treatment. Furthermore, a newly developed co-culture clonal survival assay was used to select chemical doses for the transformation assay. This assay measured the relative cloning efficiency (RCE) of chemical treatments in high-density cell cultures. In addition, transformation assay sensitivity was enhanced through the use of improved methods to solubilize many chemicals. From a group of 24 chemicals tested in at least two trials, clear evidence of chemical-induced transformation was detected for 12 chemicals (aphidicolin, barium chloride-2H2O, 5-bromo-2'-deoxyuridine, C.I. direct blue 15, trans-cinnamaldehyde, cytosine arabinoside, diphenylnitrosamine, manganese sulfate-H2O, 2-mercaptobenzimidazole, mezerein, riddelliine, and 2,6-xylidine); 2 chemicals had equivocal activity [C.I. direct blue 218 and mono(2-ethylhexyl)phthalate], 9 chemicals were inactive [carisoprodol, chloramphenicol sodium succinate, 4-chloro-2-nitroaniline, C.I. acid red 114, isobutyraldehyde, mono(2-ethylhexyl)adipate, sodium fluoride, and 12-O-tetradecanoylphorbol-13-acetate), and 1 chemical had an indeterminate response (2,6-dinitrotoluene). All positive responses were detected in the absence of an exogenous activation system and exhibited significant activity at two or more consecutive doses. This report also presents a mathematical method that uses t-statistics for rank-ordering the potency of chemical-induced transformation responses. This model detects sensitivity differences in experiments used to evaluate chemical-induced transformation. Furthermore, it provides a method to estimate a chemical's transformation response in terms of the historical behavior of the assay, as well as its future activity. The most active of the 24 chemicals was mezerein, and the least active chemical was diphenylnitrosamine.

Transformation of BALB/c-3T3 cells: V. Transformation responses of 168 chemicals compared with mutagenicity in Salmonella and carcinogenicity in rodent bioassays.

This report describes the activities of 168 chemicals tested in a standard transformation assay using A-31-1-13 BALB/c-3T3 cells. The data set includes 84 carcinogens, 77 noncarcinogens, and 7 research chemicals. Carcinogens included 49 mutagens and 35 nonmutagens; noncarcinogens included 24 mutagens and 53 nonmutagens. The transformation assay did not use an exogenous activation system, thus, all chemical responses depended on the inherent target cell metabolic capacity where metabolic activation was required. The upper dose limit was 100 milli-osmolar because the assay could not discriminate active and inactive chemicals tested above this concentration. Certain physicochemical properties resulted in technical problems that affected chemical biological activity. For example, chemicals that reacted with plastic were usually nonmutagenic carcinogens. Similarly, chemicals that were insoluble in medium, or bound metals, were usually nonmutagenic and nontransforming. Multifactorial data analyses revealed that the transformation assay discriminated between nonmutagenic carcinogens and noncarcinogens; it detected 64% of the carcinogens and only 26% of the noncarcinogens. In contrast, the transformation assay detected most mutagenic chemicals, including 94% of the mutagenic carcinogens and 70% of the mutagenic noncarcinogens. Thus, transformation or Salmonella typuimurium mutagenicity assays could not discriminate mutagenic carcinogens from mutagenic noncarcinogens. Data analyses also revealed that mutagenic chemicals were more cytotoxic than nonmutagenic chemicals; 88% of the mutagens had an LD50 < 5 mM, whereas half of the nonmutagens had an LD50 > 5 mM. Binary data analyses of the same data set revealed that the transformation assay and rodent bioassay had a concordance of 71%, a sensitivity for carcinogens of 80.0%, and a specificity for detecting noncarcinogens of 60%. In contrast, Salmonella mutagenicity assays and rodent bioassays had a concordance of 63%, a sensitivity of 58%, and a specificity of 69%. The transformation assay complemented the Salmonella mutagenesis assay in the identification of nonmutagenic carcinogens; thus, the two assays had a combined 83% sensitivity for all carcinogens and a 75% specificity for nonmutagenic noncarcinogens.

Use of toxicological information in drug design.

This paper is an extension of the keynote address and another talk at the Symposium on the Use of Toxiciological Information in Drug Design. The symposium was organized by American Chemical Society's Chemical Information Division at the 220th National Meeting of the American Chemical Society in Washington, DC, August 20-24, 2000. We outline an approach for meeting the scientific information needs of the U.S. Food and Drug Administration (FDA). Ready access to scientific information is critical to support safety-related regulatory decisions and is especially valuable in situations where available experimental information from in vivo/in vitro studies are inadequate or unavailable. This approach also has applications for lead selection in drug discovery. A pilot electronic toxicology/safety knowledge base and computational toxicology initiative is underway in the FDA Center for Drug Evaluation and Research (CDER) that may be a prototype for an FDA knowledge base. The objectives of this effort are: (i) to strengthen and broaden the scientific basis of regulatory decisions, (ii) to provide the Agency with an electronic scientific institutional memory, (iii) to create a scientific resource for regulatory and applied research, and (iv) to establish an internal Web-based support service that can provide decision support information for regulators that will facilitate the review process and improve consistency and uniformity. An essential component of this scientific knowledge base is the creation of a comprehensive electronic inventory of CDER-regulated substances that permit identification of clusters of substances having similar chemical, pharmacological or toxicological activities, and molecular structure/substructures. Furthermore, the inventory acts as a pointer and link to other databases and critical non-clinical and clinical pharmacology/toxicology studies and reviews in FDA archives. Clusters of related substances are identified through the use of: (i) an extensive index of alternative names for each substance, (ii) a molecular structure key field consisting of a rudimentary or core structure represented as an ISIS.mol-file, (iii) global search terms (molecular group, chemical class, clinical indication, or pharmacologic activity), and (iv) molecular clustering using structure/sub-structure similarity indices. The information contained in a toxicology knowledge database has limited value unless means are available to extract information, identify relationships, and create and test hypotheses. One such means is computational toxicology, also called in silico toxicology, ComTox, or e-TOX. Computational toxicology is the application of computer technology and information processing (informatics) to analyze, model, and estimate chemical toxicity based upon structure activity relationships (SAR). A computational toxicology software package, MCASE, has been evaluated and successfully improved by CDER through the incorporation of data from FDA archives and concomitant alterations of the logic used in the interpretation of the results to reflect the data analysis and hazard identification practices and priorities of the Center. Our modifications and uses of the MCASE program are discussed in detail.

Threshold of estimated toxicity for regulation of indirect food additives.

In response to the objectives of this ATSDR workshop, 2 new procedures are described for assessing the safe use of indirect food additives. First, this workshop provided a timely forum in which to describe a newly proposed Threshold of Regulation (T/R) Policy under which the Food and Drug Administration (FDA) would exempt certain indirect food additives from the formal premarket petition process. Second, this workshop offered an opportunity to discuss 2 circumstances in which Quantitative Structure Activity Relationship (QSAR) methodologies might be utilized in the future to provide decision-support information for substances used in food-contact articles.

Induction of morphological transformation by coal-dust extract in BALB/3T3 A31-1-13 cell line.

The transforming activity of coal dust extracts was studied using BALB/3T3 clone A31-1-13 cells. Coal-dust extracts, both nitrosated and nonnitrosated, induced cell transformation in a dose-response manner. However, the transformation frequency was higher with the nitrosated than with the nonnitrosated extract. All transformed cell lines derived from coal-dust extract-induced foci showed biological characteristics of neoplastic transformation such as loss of contact inhibition and anchorage-independent growth. These results appear to support a hypothesis of coal mine dust causation of gastric cancer in coal miners.

A new highly specific method for predicting the carcinogenic potential of pharmaceuticals in rodents using enhanced MCASE QSAR-ES software.

This report describes in detail a new quantitative structure-activity relational expert system (QSAR-ES) method for predicting the carcinogenic potential of pharmaceuticals and other organic chemicals in rodents, and a beta-test evaluation of its performance. The method employs an optimized, computer-automated structure evaluation (MCASE) software program and new database modules which were developed under a Cooperative Research and Development Agreement (CRADA) between FDA and Multicase, Inc. The beta-test utilized 126 compounds with carcinogenicity studies not included in control database modules and three sets of modules, including: A07-9 (Multicase, Inc.), AF1-4 (FDA-OTR/Multicase, Inc.), and AF5-8 (FDA-OTR/proprietary). The investigation demonstrated that the standard MCASE(A07-9) system which had a small data-set (n = 319), detected few structure alerts (SA) for carcinogenicity (n = 17), and had poor coverage for beta-test compounds (51%). Conversely, the new, optimized FDA-OTR/MCASE(AF5-8) system had a large data-set (n = 934), detected many SA (n = 58) and had good coverage (94%). In addition, the study showed the standard MCASE(A07-9) software had poor predictive value for carcinogens and specificity for noncarcinogens (50 and 42%), detected many false positives (58%), and exhibited poor concordance (46%). Conversely, the new, FDA-OTR/MCASE(AF5-8) system demonstrated excellent predictive value for carcinogens and specificity for non-carcinogens (97%, 98%), detected only one false positive (2%), and exhibited good concordance (75%). The dramatic improvements in the performance of the MCASE were due to numerous modifications, including: (a) enhancement of the size of the control database modules, (b) optimization of MCASE SAR assay evaluation criteria, (c) incorporation of a carcinogenic potency scale for control compound activity and MCASE biophores, (d) construction of individual rodent gender- and species-specific modules, and (e) defining assay acceptance criteria for query and control database compounds.

Development of a mouse embryo limb bud cell culture system for the estimation of chemical teratogenic potential.

High-density cultures of mouse embryo limb bud cells differentiate and synthesize an extracellular matrix containing sulfated proteoglycans. Since these in vitro events are related to those that occur during fetal development, we have investigated the use of cultured limb bud cells for the analysis of the activities of chemical teratogens. We have established the conditions for the use of the radiochemicals 35SO=4 and 3H-thymidine for the assessment of chemical effects on sulfated proteoglycan and DNA synthesis, respectively, in mouse limb bud cells. By performing double-labeling experiments in the presence of test chemicals, the preferential inhibition of either proteoglycan synthesis or DNA synthesis could be demonstrated for 19 of 22 known mouse teratogens tested. The five nonteratogens tested did not cause significant differences in the inhibition of either macromolecular class. The overall predictive accuracy of the system was approximately 89%, and the false-negative rate was approximately 14.8%. No false positives were observed. These data showed that this cell culture system differentiated between the activities of a limited set of selected mouse teratogens and nonteratogens, suggesting that cultured mouse embryo limb bud cells may constitute the basis for the development of a powerful tool for analyses of chemical teratogenic potential.

Commonalities in the structural determinants of toxicity in fish and mammals.

The CASE program, an expert structure-activity relational system, was used to identify the structural determinants associated with inhibition of the human isozyme P4502D, toxicity of cultured murine Balb 3T3 cells, induction of alpha 2u-globulin-associated nephropathy in male rats, systemic toxicity in mice and rats, and acute toxicity in minnows. Comparison of the structural determinants thus identified revealed a significant mechanistic overlap between the determinants of cellular toxicity and systemic toxicity in mice, rats, and minnows.

Efficient literature searching in diffuse topics: lessons from a systematic review of research on communicating risk to patients in primary care.

Using the example of communication about risk in a primary care setting, this paper puts forward a method of developing and evaluating a detailed search strategy for locating the literature for a systematic review of a 'diffuse' subject. The aim of this paper is to show how to develop a search strategy that maximizes both recall and precision while keeping search outputs manageable. Six different databases were used, namely Medline, Embase, PsychLIT, CancerLIT, Cinahl and Social Science Citation Index (SSCI). The searches were augmented by hand-searching, contacting authors, citation searching and reference lists from included papers. Other databases were searched but yielded no extra references for this subject matter. Of the 99 papers included, 80 were indexed on Medline. The Medline search strategy identified 54 of them and the remaining 26 were located on other databases. The 19 further unique references were found using the other databases and methods of retrieval. A combination of several databases must be used to maximize recall and to increase the precision of searches on individual databases, thus improving the overall efficiency of the search.