Cigarette advertising and onset of smoking in children: questionnaire survey.

OBJECTIVE: To investigate uptake of smoking in a cohort of 11 to 12 year olds related to awareness of advertised cigarette brands named. DESIGN: Self completed questionnaires administered to whole classes of schoolchildren in June 1993 and June 1994. SETTING: Primary, middle, and secondary schools in the north and south of England. SUBJECTS: 1450 pupils aged 11 and 12 years at the time of the first survey. MAIN OUTCOME MEASURES: Onset of smoking and brands smoked by the second survey related to cigarette brands named in the first one. Less advertised brands were used as the base for calculating odds ratios. RESULTS: Girls who named the most advertised brands-namely, Benson and Hedges alone (odds ratio = 2.50, 95% confidence interval = 1.18 to 5.30) or Benson and Hedges and Silk Cut (2.15, 1.04 to 4.42) in the first survey were at greatest risk of taking up smoking by the second one. The difference was similar but not significant for boys. Boys and girls who named the least advertised brands in the first survey were at no greater risk of taking up smoking by the second survey than those who named no brands (boys odds ratio = 0.49 (0.24 to 1.01); girls 0.79 (0.38 to 1.62)). New smokers were more likely to smoke any available brand (29.5%) or a less advertised brand such as Embassy (24.6%) than the most advertised ones, Benson and Hedges (19.7%) and Silk Cut (14.8%). Established smokers were more selective, only 15% smoking any available brand and 38.3% smoking Benson and Hedges. CONCLUSIONS: Cigarette advertising appears to increase children''s awareness of smoking at a generic level and encourages them to take up the behaviour, beginning with any cigarettes which are available and affordable.     

Identifying plant functional types using floristic data bases: Ecological correlates of plant range size

Abstract. In an effort to identify ‘plant functional types’, the islands floras of Great Britain and Kríti (Crete, Greece) were examined separately for ecological correlates of plant range size. Plant functional types (PFTs) were defined here as categories into which plants could be grouped on the basis of attributes that predict greater or lesser sensitivity to ecological variability. Plant range size indicates commonness of a species and was assumed to be a proxy for ‘ecological flexibility’, i.e. species of larger range sizes can better withstand environmental change and differences than species of smaller range sizes. Using evolutionary comparative methods that account for the effect of taxonomic relatedness, both floras were investigated for the effects on range size of woodiness vs. non-woodiness, trees vs. shrubs, trees vs. herbs and shrubs vs. herbs. The British flora was examined additionally for the effects of wind- vs. non-wind-pollination, self vs. animal pollination and animal vs. non-animal fruit dispersal on range size. Two analyses showed significant effects on range size: for British species, trees had larger ranges than shrubs, and wind- pollinated species had larger ranges than non-wind-pollinated species. It is suggested that the lack of a similar pattern for shrubs and trees in Kríti is because the lower water availability of Kríti imbues shrubs with an ecophysiological advantage not relevant in plants of Great Britain. That trees have larger range sizes than shrubs in Great Britain is ascribed to the greater importance of competition for light when other factors are not at issue. The greater range of wind-pollinated than non-windpollinated species in Great Britain is postulated to be because both mutualists must be capable of invading new areas. This may be termed a ‘cost of mutualism’. In terms of PFTs, the results indicate that ‘life-form’ is too broad a classification category by which to differentiate relative sensitivity to environmental variability in Great Britain, in that there were significant differences in range size of trees and shrubs, but not between either of the two categories and herbs, or between woody and non-woody plants. Although pollination type may predict relative sensitivity to variation in Great Britain, dispersal type will not. Finally, differences between Great Britain and Kríti in relative range size patterns suggests that plant functional types may be specific to a region or set of conditions.     

Microsomal and cytosolic cytochrome P450 mediated benzo(a)pyrene hydroxylation in Pleurotus pulmonarius

Summary Microsomal and soluble fractions of Pleurotus pulmonarius exhibited a reduced carbon monoxide difference spectrum with P450 maxima at 448nm and 450–452nm respectively. Substrate induced Type I spectra were observed on addition of benzo(a)pyrene to both fractions. Benzo(a)pyrene hydroxylation was measured using the aryl hydrocarbon hydroxylase assay and was observed to be P450 dependent as indicated by carbon monoxide inhibition together with the substrate binding characteristics. The activity of the fractions were observed to give K_m of 200mM and 660mM and V_max of 1.25 nmol/min/nmol P450 and 0.57 nmol/min/nmol P450 for the microsomal and cytosolic fractions respectively.     

Characterization of diverse primary herpes simplex virus type 1 gB-specific cytotoxic T-cell response showing a preferential V beta bias.

The glycoprotein B (gB) from herpes simplex virus type I is a major target of cytotoxic T lymphocytes (CTL) in C57BL/6 mice. The majority of these T cells are directed to a single Kb-restricted determinant, gB498-505. We have analyzed the T-cell receptor (TCR) usage in gB-specific CTL lines derived shortly after virus infection. The CTL populations preferentially used two V beta regions, a dominant V beta 10 element and a subdominant V beta 8 element. Detailed sequence analysis revealed considerable TCR beta-chain heterogeneity despite a striking level of predicted amino acid conservation at the V beta-D beta junction. This junction forms part of the third hypervariable loop of the TCR thought to directly contact the major histocompatibility complex-bound antigenic peptide. The results reveal considerable diversity within the primary T cells responding to a single viral determinant while still maintaining a high degree of TCR V beta bias and sequence conservation at the V-D-J junction.     

Characterization and Distribution of a Cloned Rat μ-Opioid Receptor

Abstract: We have cloned and expressed a rat brain cDNA, TS11, that encodes a μ-opioid receptor based on pharmacological, physiological, and anatomical criteria. Membranes were prepared from COS-7 cells transiently expressing TS11 bound [³H]diprenorphine with high affinity (K_D = 0.23 ± 0.04 nM). The rank order potency of drugs competing with [³H]diprenorphine was as follows: levorphanol (K_i = 0.6 ± 0.2 nM) ≈β-endorphin (K_i = 0.7 ± 0.5 nM) ≈ morphine (K_i = 0.8 ± 0.5 nM) ≈ [d -Ala², N-Me-Phe⁴,Gly-ol⁵]-enkephalin (DAMGO; K_i = 1.6 ± 0.5 nM) ? U50,488 (K_i = 910 ± 0.78 nM) > [d -Pen^2,5]-enkephalin (K_i = 3,170 ± 98 nM) > dextrorphan (K_i = 4,100 ± 68 nM). The rank order potencies of these ligands, the stereospecificity of levorphanol, and morphine's subnanomolar K_i are consistent with a μ-opioid binding site. Two additional experiments provided evidence that this opioid-binding site is functionally coupled to G proteins: (a) In COS-7 cells 50 µM 5′-guanylylimidodiphosphate shifted a fraction of receptors with high affinity for DAMGO (IC₅₀ = 3.4 ± 0.5 nM) to a lower-affinity state (IC₅₀ = 89.0 ± 19.0 nM), and (b) exposure of Chinese hamster ovary cells stably expressing the cloned μ-opioid receptor to DAMGO resulted in a dose-dependent, naloxone-sensitive inhibition of forskolin-stimulated cyclic AMP production. The distribution of mRNA corresponding to the μ-opioid receptor encoded by TS11 was determined by in situ hybridization to brain sections prepared from adult female rats. The highest levels of μ-receptor mRNA were detected in the thalamus, medial habenula, and the caudate putamen; however, significant hybridization was also observed in many other brain regions, including the hypothalamus.     

Partial restoration of impaired alpha1-adrenergic responsiveness in parotid cells of aged rats by S-adenosylmethionine treatment

The age related decrease in alpha₁-adrenergic stimulated inositol 1,4,5 trisphosphate (IP₃) production in parotid cells of aged rats can be partially restored by treatment with S-adenosylmethionine (SAM). This effect is completely blocked by S-adenosyl homocysteine (SAH) and occurs in association with an increase in the conversion of phosphatidylethanolamine to phosphatidylcholine and a decrease in membrane viscosity. In contrast, SAM treatment actually inhibits stimulated IP₃ production in cells of young rats. The membrane viscosity of these cells is lower than that of those from aged rats. Although conversion of phosphatidylethanolamine to phosphatidylcholine is enhanced, no further decrease in membrane viscosity is elicited in young cell preparations. These findings suggest that age changes in the membrane environment may result in impaired alpha₁-adrenergic signal transduction and that such alterations may be at least partially reversible by SAM treatment.     

Role of arginine-43 and arginine-69 of the Hin recombinase catalytic domain in the binding of Hin to the hix DNA recombination sites

The Hin recombinase mediates the site-specific inversion of a segment of the Salmonella chromosome between two flanking 26 bp hix DNA recombination sites. Mutations in two amino acid residues, R43 and R69 of the catalytic domain of the Hin recombinase, were identified that can compensate for loss of binding resulting from elimination of certain major and minor groove contacts within the hix recombination sites. With one exception, the R43 and R69 mutants were also able to bind a hix sequence with an additional 4 bp added to the centre of the site, unlike wild-type Hin. Purified Hin mutants R43H and R69C had both partial cleavage and inversion activities in vitro while mutants R43L, R43C, R69S, and R69P had no detectable cleavage and inversion activities. These data support a model in which the catalytic domain plays a role in DNA-binding specificity, and suggest that the arginine residues at positions 43 and 69 function to position the Hin recombinase on the DNA for a step in the recombination reaction which occurs either at and/or prior to DNA cleavage.     

Distinct Requirements for Somatic and Germline Expression of a Generally Expressed Caernorhabditis Elegans Gene

In screening for embryonic-lethal mutations in Caenorhabditis elegans, we defined an essential gene (let-858) that encodes a nuclear protein rich in acidic and basic residues. We have named this product nucampholin. Closely homologous sequences in yeast, plants, and mammals demonstrate strong evolutionary conservation in eukaryotes. Nucampholin resides in all nuclei of C. elegans and is essential in early development and in differentiating tissue. Antisense-mediated depletion of LET-858 activity in early embryos causes a lethal phenotype similar to characterized treatments blocking embryonic gene expression. Using transgene-rescue, we demonstrated the additional requirement for let-858 in the larval germline. The broad requirements allowed investigation of soma-germline differences in gene expression. When introduced into standard transgene arrays, let-858 (like many other C. elegans genes) functions well in soma but poorly in germline. We observed incremental silencing of simple let-858 arrays in the first few generations following transformation and hypothesized that silencing might reflect recognition of arrays as repetitive or heterochromatin-like. To give the transgene a more physiological context, we included an excess of random genomic fragments with the injected DNA. The resulting transgenes show robust expression in both germline and soma. Our results suggest the possibility of concerted mechanisms for silencing unwanted germline expression of repetitive sequences.     

A Test of Neutrality Based on Interlocus Associations

The evolutionary processes governing variability within genomic regions of low recombination have been the focus of many studies. Here, I investigate the statistical properties of a measure of intrlocus genetic associations under the assumption that mutations are selectively neutral and sites are completely linked. This measure, denoted Z(nS), is based on the squared correlation of allelic identity at pairs of polymorphic sites. Upper bounds for Z(nS) are determined by simulations. Various deviations from the neutral model, including several different forms of natural selection, will inflate the value of Z(nS) relative to its neutral theory expectations. Larger than expected values of Z(nS) are observed in genetic samples from the yellow-ac-scute and Adh regions of Drosophila melanogaster.