Antibody-based profiling of the phosphoinositide 3-kinase pathway in clinical prostate cancer.

PURPOSE: As kinase inhibitors transition from the laboratory to patients, it is imperative to develop biomarkers that can be used in the clinic. The primary objectives are to identify patients most likely to benefit from molecularly targeted therapies and to document modulation of the drug target. Constitutive activation of the phosphoinositide 3-kinase (PI3K) pathway and its downstream effectors, as a result of PTEN loss or by other mechanisms, occurs in a high proportion of prostate cancers, making it an ideal template for the design of clinical trials involving PI3K pathway inhibitors. Prostate cancers also present unique organ-specific challenges, in that tumors are heterogeneous and diagnostic tissue is extremely limited. EXPERIMENTAL DESIGN: Working within these limitations, we have developed a set of immunohistochemical assays that define activation of the PI3K pathway in clinical samples. Results and CONCLUSIONS: Using both univariate and multivariate analyses, we show that loss of PTEN is highly correlated with the activation of AKT, and this, in turn, is associated with the phosphorylation of S6, one of its main effectors. These three antibodies are potentially able to define a molecular signature of PTEN loss and/or AKT pathway activation in prostate cancer.     

Screening for complement deficiency in bacterial meningitis

Seventy-seven children with bacterial meningitis were screened for complement deficiency. Both the classical and the alternate pathways were normal in 75 patients. Transiently reduced total haemolytic activity of the classical pathway was documented in a boy with meningococcal meningitis. Total haemolytic activity of both the classical and the alternate pathways were reduced in another patient with pneumococcal meningitis: individual complement components determination indicated predominant activation of the alternate pathway.     

Identification of differentially expressed genes in aflatoxin B1- treated cultured primary rat hepatocytes and Fischer 344 rats

Aflatoxin B1 (AFB1), a mutagen and hepatocarcinogen in rats and humans, is a contaminant of the human food supply, particularly in parts of Africa and Asia. AFB1-induced changes in gene expression may play a part in the development of the toxic, immunosuppressive and carcinogenic properties of this fungal metabolite. An understanding of the-role of AFB1 in modulating gene regulation should provide insight regarding mechanisms of AFB1-induced carcinogenesis. We used three PCR- based subtractive techniques to identify AFB1-responsive genes in cultured primary rat hepatocyte RNA: differential display PCR (DD-PCR), representational difference analysis (RDA) and suppression subtractive hybridization (SSH). Each of the three techniques identified AFB1- responsive genes, although no individual cDNA was isolated by more than one technique. Nine cDNAs isolated using DD-PCR, RDA or SSH were found to represent eight genes that are differentially expressed as a result of AFB1 exposure. Genes whose mRNA levels were increased in cultured primary rat hepatocytes after AFB1 treatment were corticosteroid binding globulin (CBG), cytochrome P450 4F1 (CYP4F1), alpha-2 microglobulin, C4b-binding protein (C4BP), serum amyloid A-2 and glutathione S-transferase Yb2 (GST). Transferrin and a small CYP3A-like cDNA had reduced mRNA levels after AFB1 exposure. Full-length CYP3A mRNA levels were increased. When liver RNA from AFB1-treated male F344 rats was evaluated for transferrin, CBG, GST, CYP3A and CYP4F1 expression, a decrease in transferrin mRNA and an increase in CBG, GST, CYP3A and CYP4F1 mRNA levels was also seen. Analysis of the potential function of these genes in maintaining cellular homeostasis suggests that their differential expression could contribute to the toxicity associated with AFB1 exposure.      

A descriptive analysis of STD prevalence among urban pregnant African-American teens: data from a pilot study.

OBJECTIVE: To assess the prevalence of sexually transmitted diseases (STDs) among a sample of African-American adolescent females at the time of their first prenatal visit and to assess key characteristics of those testing positive for sexually transmitted diseases. The study also determined differences in these characteristics between adolescents who were and those who were not diagnosed with an STD. METHODS: One-hundred-and-seventy pregnant African-American adolescents (aged 14-20 years; mean = 17.5 years) receiving their first prenatal visit were recruited at a prenatal clinic located in a large urban hospital. Biological assessment included nucleic acid amplification testing for gonococcal, chlamydial, and trichomonal infections. Rapid plasma reagin testing assessed infection with syphilis. A self-administered survey and in-depth face-to-face interview were used to collect detailed information assessing adolescents' sociodemographic characteristics, psychosocial indices, and their recent sexual risk behaviors. Data were analyzed using Student's t-tests and contingency table analyses, respectively, for continuous and categorical variables. RESULTS: Overall, 23.5% tested positive for one of the four STDs. Thirteen percent were infected with Chlamydia trachomatis, 1.2% with Neisseria gonorrhoeae, 8.9% with Trichomonas vaginalis, and 1.2% with Treponema pallidum. More than one-half reported recent (past 6 months) treatment for an STD, 30% of these tested positive for at least one of the four STDs assessed. Adolescents testing positive for STDs held favorable attitudes toward condom use, but levels of sexual risk were generally high. There were no sociodemographic, psychosocial, and sexual-risk differences between those testing positive and negative. CONCLUSION: Findings support STD screening efforts targeting pregnant adolescents. Providing clinic-based counseling and prevention education programs to pregnant adolescents regardless of apparent risk factors may also be warranted.     

Application of the Attitude-Social Influence-Efficacy Model to Condom Use Among African-American STD Clinic Patients: Implications for Tailored Health Communication

The purpose of the current investigation was to apply the attitude-social influence-efficacy (ASE) model to achieve a theory-based understanding of condom use among low income, heterosexually active African-American STD clinic patients. N = 293 participants were recruited from a large, publicly-funded metropolitan STD clinic in the Southeastern United States and surveyed using an ACASI computer program. Results indicated that several ASE variables exhibited meaningful relationships with condom stages of change in univariate analyses, replicating patterns found in previous research. Fewer variables remained significant in multivariate analyses, however. There was also some support for the proposition that early stage movement (e.g., Precontemplation to Contemplation) is based more upon perceptions of condom use (e.g., pros, perceived norms), whereas later stage movement (e.g., Preparation to Action/Maintenance) is based more upon perceived and actual skills acquisition (e.g., condom self-efficacy, negotiation strategies). Results varied with regard to main and casual condom stage of change. Implications for developing tailored HIV prevention interventions with heterosexual African-Americans are discussed.     

Effect of Isomorphous Substitution on the Thermal Decomposition Mechanism of Hydrotalcites

Hydrotalcites have many important applications in catalysis, wastewater treatment, gene delivery and polymer stabilization, all depending on preparation history and treatment scenarios. In catalysis and polymer stabilization, thermal decomposition is of great importance. Hydrotalcites form easily with atmospheric carbon dioxide and often interfere with the study of other anion containing systems, particularly if formed at room temperature. The dehydroxylation and decomposition of carbonate occurs simultaneously, making it difficult to distinguish the dehydroxylation mechanisms directly. To date, the majority of work on understanding the decomposition mechanism has utilized hydrotalcite precipitated at room temperature. In this study, evolved gas analysis combined with thermal analysis has been used to show that CO₂ contamination is problematic in materials being formed at RT that are poorly crystalline. This has led to some dispute as to the nature of the dehydroxylation mechanism. In this paper, data for the thermal decomposition of the chloride form of hydrotalcite are reported. In addition, carbonate-free hydrotalcites have been synthesized with different charge densities and at different growth temperatures. This combination of parameters has allowed a better understanding of the mechanism of dehydroxylation and the role that isomorphous substitution plays in these mechanisms to be delineated. In addition, the effect of anion type on thermal stability is also reported. A stepwise dehydroxylation model is proposed that is mediated by the level of aluminum substitution.