Recruitment in an indicated prevention program for externalizing behavior - parental participation decisions.

BACKGROUND: Parents are the ones who decide whether or not to participate in parent focused prevention trials. Their decisions may be affected by internal factors (e.g., personality, attitudes, sociodemographic characteristics) or external barriers. Some of these barriers are study-related and others are intervention-related. Internal as well as external barriers are especially important at the screening stage, which aims to identify children and families at risk and for whom the indicated prevention programs are designed. Few studies have reported their screening procedure in detail or analyzed differences between participants and dropouts or predictors of dropout. Rates of participation in prevention programs are also of interest and are an important contributor to the efficacy of a prevention procedure. METHODS: In this study, we analyzed the process of parent recruitment within an efficacy study of the indicated Prevention Program for Externalizing Problem behavior (PEP). We determined the retention rate at each step of the study, and examined differences between participants and dropouts/decliners. Predictors of dropout at each step were identified using logistic regression. RESULTS: Retention rates at the different steps during the course of the trial from screening to participation in the training ranged from 63.8% (pre-test) to 81.1% (participation in more than 50% of the training sessions). Parents who dropped out of the study were characterized by having a child with lower symptom intensity by parent rating but higher ratings by teachers in most cases. Low socioeconomic status and related variables were also identified as predictors of dropout in the screening (first step) and for training intensity (last step). CONCLUSIONS: Special attention should be paid to families at increased risk for non-participation when implementing the prevention program in routine care settings. TRIAL REGISTRATION: ISRCTN12686222.

Regulation of AmtR-controlled gene expression in Corynebacterium glutamicum: mechanism and characterization of the AmtR regulon.

AmtR, the master regulator of nitrogen control in Corynebacterium glutamicum, represses transcription of a number of genes during nitrogen surplus. Repression is released by an interaction of AmtR with signal transduction protein GlnK. As shown by pull-down assays and gel retardation experiments, only adenylylated GlnK, which is present in the cells during nitrogen limitation, is able to bind to AmtR. The AmtR regulon was characterized in this study by a combination of bioinformatics, transcriptome and proteome analyses. At least 33 genes are directly controlled by the repressor protein including those encoding transporters and enzymes for ammonium assimilation (amtA, amtB, glnA, gltBD), urea and creatinine metabolism (urtABCDE, ureABCEFGD, crnT, codA), a number of biochemically uncharacterized enzymes and transport systems (NCgl1099, NCgl1100, NCgl 1915-1918) as well as signal transduction proteins (glnD, glnK). For the AmtR regulon, an AmtR box has been defined which comprises the sequence tttCTATN6AtAGat/aA. Furthermore, the transcriptional organization of AmtR-regulated genes and operons was characterized.

Vanillate metabolism in Corynebacterium glutamicum.

Corynebacterium glutamicum, a Gram-positive soil bacterium belonging to the mycolic acids-containing actinomycetes, is able to use the lignin degradation products ferulate, vanillate, and protocatechuate as sole carbon sources. The gene cluster responsible for vanillate catabolism was identified and characterized. The vanAB genes encoding vanillate demethylase are organized in an operon together with the vanK gene, coding for a transport system most likely responsible for protocatechuate uptake. While gene disruption mutagenesis revealed that vanillate demethylase is indispensable for ferulate and vanillate utilization, a vanK mutation does not lead to a complete growth arrest but to a decreased growth rate on protocatechuate, indicating that one or more additional protocatechuate transporter(s) are present in C. glutamicum.

Molecular identification of the urea uptake system and transcriptional analysis of urea transporter- and urease-encoding genes in Corynebacterium glutamicum.

The molecular identification of the Corynebacterium glutamicum urea uptake system is described. This ABC-type transporter is encoded by the urtABCDE operon, which is transcribed in response to nitrogen limitation. Expression of the urt genes is regulated by the global nitrogen regulator AmtR, and an amtR deletion strain showed constitutive expression of the urtABCDE genes. The AmtR repressor protein also controls transcription of the urease-encoding ureABCEFGD genes in C. glutamicum. The ure gene cluster forms an operon which is mainly transcribed in response to nitrogen starvation. To confirm the increased synthesis of urease subunits under nitrogen limitation, proteome analyses of cytoplasmic protein extracts from cells grown under nitrogen surplus and nitrogen limitation were carried out, and five of the seven urease subunits were identified.

Utilization of creatinine as an alternative nitrogen source in Corynebacterium glutamicum.

In order to utilize different nitrogen sources and to survive situations of nitrogen limitation, microorganisms have developed several mechanisms to adapt their metabolism to changes in the nitrogen supply. In this communication, the use of creatinine as an alternative nitrogen source in Corynebacterium glutamicum, the identification of a membrane protein involved in creatinine uptake, the transcriptional regulation of the corresponding gene, and expression regulation of the gene encoding the creatinine deaminase are reported. As shown by mutant analyses, RNA hybridization experiments and real-time PCR, the expression of two genes, crnT and codA, is increased in response to nitrogen limitation, and regulation depends on the global nitrogen regulator AmtR. In addition, synthesis of creatinine deaminase during nitrogen starvation was shown by two-dimensional gel electrophoresis and MALDI-TOF-MS followed by peptide mass fingerprint analysis.

Nitrogen assimilation in Corynebacterium diphtheriae: pathways and regulatory cascades.

Genes encoding proteins for ammonium uptake, assimilation, and the nitrogen regulatory system in Corynebacterium diphtheriae were studied on basis of homology searches using Corynebacterium glutamicum genes as query sequences. Regulation of transcription of these genes in response to nitrogen starvation was analyzed by RNA hybridization experiments and knock-out mutants were generated to verify the function of distinct genes. In this communication, we were able to identify the key components of ammonium assimilation pathways and nitrogen regulation in C. diphtheriae. Moreover, we show in this study that molecular biology methods and vectors developed for C. glutamicum can be applied in C. diphtheriae. The results obtained strengthens the role of C. glutamicum as a model organism for mycolic acids-containing actinomycetes.