Reasons adolescents don't use drugs: exploring a "depth of acceptance" model.

Adolescent's reasons for not using drugs were examined for evidence of factors that might lead to differential resistance to drug use. Six thousand eight-hundred and forty-one sixth, eighth, tenth, and twelfth grade students were administered a comprehensive drug survey which included: 1) demographic information, 2) reasons not to use drugs, and 3) self-reports of lifetime and current (30-day) drug use across sixteen drug categories. The reasons for not using drugs were then factor analyzed and the results compared to a "Depth of Acceptance" (DOA) model consisting of four orientations: External Outcome, Social, and Personal. These orientations are thought both to represent distinct immunization factors and to be differentially related in strength to lifetime and current drug use. Confirmatory factor analysis revealed a close fit between the hypothesized orientations and factor loadings among the sixteen items. Collectively, the sixteen items were also found to be excellent predictors of both lifetime and current drug use. While multiple stepwise regression analyses did reveal differential predictive strengths between orientation and drug use, the misclassification of a single item apparently attenuated the results for Social Orientation. The DOA model appears to provide a useful framework for "fine-tuning" prevention messages based on factors that immunize against drug use.

The gvpA/C cluster of Anabaena flos-aquae has multiple copies of a gene encoding GvpA.

Southern analysis of genomic DNA from Anabaena flos-aquae revealed that the genes encoding the two authenticated protein components of cyanobacterial gas vesicles, GvpA and GvpC, were carried on the same 4.9-kb HindIII restriction fragment. By comparing the hybridization intensities observed when either gvpA- or gvpC-specific oligonucleotides are bound to this HindIII fragment, we calculated that the A. flos-aquae genome contains seven copies of gvpA and a single copy of gvpC. The nucleotide sequence of the longest cloned section of the gvpA/C cluster of A. flos-aquae DNA revealed the presence of four complete copies of gvpA and part of a fifth copy located upstream from a single copy of gvpC; no clones carrying the entire gvpA/C-bearing HindIII fragment were identified. The distribution of Sau3A restriction sites throughout the gvpA/C-bearing genomic HindIII fragment resembled that seen in the cloned portion of the gvpA/C cluster and is consistent with that expected for a cluster containing seven copies of gvpA and one copy of gvpC. The length of transcripts that hybridize to both gvpA and gvpC on Northern blots was consistent with a 7gvpA + 1gvpC transcriptional unit.

Antibodies to the N-terminal sequence of GVPa bind to the ends of gas vesicles.

Antibodies were raised against intact gas vesicles of Anabaena flos-aquae, and against a synthetic peptide (GVPaNT) whose sequence is identical to the N-terminal region of the main gas vesicle protein, GVPa. A two-stage centrifugation procedure is described for separating gold-labelled antibodies bound to gas vesicles from unbound antibodies. The GVPaNT antibody bound to gas vesicles that had been previously rinsed with SDS to remove the outer gas vesicle protein, GVPc. Treatment with this antibody caused the gas vesicles to aggregate together end-to-end rather than side-by-side. The binding of the anti-GVPaNT-immunogold particles to the gas vesicle was restricted to the conical ends of the structure. These observations indicate that the sequence to which the GVPaNT antibodies were raised, residues 1 to 13 of the GVPa molecule, is exposed only at the outer surface of the cones and that it is normally obscured by GVPc. As GVPa forms both the conical ends and the cylindrical midsection of the gas vesicle, exposure of the N-terminal sequence only in the cones must be due to differences in the contact between adjacent GVPa molecules in the central cylinders and end-cones.

Cloning and characterization of the 5' end and promoter region of the chicken acetyl-CoA carboxylase gene.

Acetyl-CoA carboxylase is a rate-limiting enzyme in the biogenesis of long-chain fatty acids. In the present study, the 5' end and flanking region of the acetyl-CoA carboxylase (ACC) gene was analysed in the chicken. A genomic clone was isolated containing the first three exons, the third one containing the ATG codon. Using nuclease-mapping experiments and primer-extension analyses, the transcription-initiation site was located 153 nucleotides upstream of the ATG codon. In contrast with rat ACC gene expression, reverse transcriptase PCR analysis performed on chicken liver mRNA did not reveal alternative splicing in the 5'-untranslated region of these messengers. The promoter region is very G+C rich, and contains no TATA or CAAT boxes. Analysis by transient transfection in a human hepatoma cell line (HepG2) demonstrates that the promoter activity requires the presence of symmetrical sequences located upstream of the GC boxes. Transcription of this gene is found to be controlled by tri-iodothyronine in HepG2 cells, but the sequence responsible for the tri-iodothyronine response is not the consensus tri-iodothyronine-responsive element localized in the promoter. These results bring new insights to the regulation of the chicken ACC gene which differs from that of the rat.

Characterization of the chicken fatty acid synthase gene 5' part and promoter region.

Fatty acid synthase activity has been shown to be regulated mainly at the transcriptional level under both dietary and hormonal influences. As a first step towards elucidating the factors involved, we isolated and characterized chicken genomic clones encompassing the 5' part of the chicken fatty acid synthase gene and its flanking region. The entire region of the cloned DNA spans 30 kb, and the first three exons of the gene were mapped to a 6.3-kb genomic fragment. The transcription initiation site was determined after subcloning the cDNA which encodes the 5' end of the mRNA. The first exon, which was 129 bp long, was located approximately 5.3 kb upstream of the second exon, which contained the start codon. In the 5' flanking region, putative TATA and CAAT boxes were located 30 and 92 bp, respectively, upstream of the transcription initiation site. The 5' flanking region contained numerous sequences corresponding to consensus binding sites for transcription factors. Various lengths of flanking sequences extending up to 1028 bp upstream of the transcription initiation site and containing 100 bp of the first exon were linked to the bacterial chloramphenicol acetyltransferase gene; in this study, these constructs were analyzed in transient transfection assays in human hepatoma cells. The proximal 125-bp sequence upstream of the transcription start site was shown to be a basal promoter. The cloning and characterization of the chicken fatty-acid synthase gene provides some further insight into the regulation of fatty acid synthesis in birds as compared to mammals.

Comparison of the metabolic and toxic effects of 2-chloropropionate and dichloroacetate.

The metabolic and toxic effects of 2-chloropropionate and dichloroacetate, activators of the pyruvate dehydrogenase complex, were compared. In 4-hr fasted mice, the oral LD50 values for 2-chloropropionate and dichloroacetate were 15.4 +/- 0.1 and 32.1 +/- 1.1 mmol/kg, respectively. In suckling rats, both compounds effectively lowered blood lactate and glucose levels and increased blood ketone bodies. Although comparable effects were brought about by both compounds on other metabolites, dichloroacetate caused a greater increase in blood ketone bodies. In a prolonged oral toxicity study using male rats, both compounds decreased growth rate and food consumption and caused neurotoxic effects. Both compounds brought about hind limb weakness, slower nerve conduction velocities and decreased diameter of tibial nerves. 2-Chloropropionate treatment caused testicular abnormalities manifested by testicular maturation arrest and degeneration of germ cells. 2-Chloropropionate-treated rats had significantly lower plasma triacylglycerol levels than control or dichloroacetate-treated rats. In mature rats, total serum ketone bodies were increased by dichloroacetate but not significantly elevated by 2-chloropropionate. Although 2-chloropropionate may lack sufficient safety to warrant chronic use in humans, it is a useful research tool for studying the metabolic effects of activation of the pyruvate dehydrogenase complex. Since 2-chloropropionate is not converted to oxalate and is not as ketogenic as dichloroacetate, 2-chloropropionate may be useful clinically in situations requiring only short-term therapy.