Communicating evidence-based information on cancer prevention to state-level policy makers

Opportunities exist to disseminate evidence-based cancer control strategies to state-level policy makers in both the legislative and executive branches. We explored factors that influence the likelihood that state-level policy makers will find a policy brief understandable, credible, and useful.

Evidence for active cyclic electron flow in twig chlorenchyma in the presence of an extremely deficient linear electron transport activity.

Fast and slow chlorophyll fluorescence induction curves at high and low actinic visible light, post-illumination changes in fluorescence yield and reflectance changes at 820 nm induced by far-red light were used to characterize the state of PSII and PSI and their electron transport capabilities in chlorophyllous twig cortices of Eleagnus angustifolius L., while corresponding leaves served as controls. Twigs displayed low dark-adapted PSII photochemical efficiencies and particularly low linear electron transport rates when illuminated. In addition, their PSII population was characterized by a high proportion of inactive, non-Q(B)-reducing centers and an incomplete quenching of fluorescence during the slow induction phase. It is suggested that PSII in twigs is an inefficient electron donor to PSI and/or the reductive pentose phosphate cycle. Yet, in spite of this apparent PSII deficiency, pools of intermediate electron carriers and potential PSI activity were more than sufficient to support the observed linear electron transport rates. Moreover, the rate of PSI reduction upon far-red/dark transitions and the magnitude of fluorescence yield increase upon white light/dark transitions were compatible with an efficient electron flow to PSI from stromal donors in the absence of PSII activity. We conclude that corticular chlorenchyma may be actively engaged in cyclic at the expense of a linear electron flow and discuss the possible physiological significance of this finding in conjunction with the particular microenvironmental conditions encountered within twigs.

The osmolality of the cell suspension regulates phycobilisome-to-photosystem I excitation transfers in cyanobacteria.

The chlorophyll a (Chla) fluorescence of cyanobacteria, which at physiological temperature originates from photosystem (PS) II holochromes, is suppressed in hyperosmotic suspension, and enhanced in hypo-osmotic suspension (G.C. Papageorgiou, A. Alygizaki-Zorba, Biochim. Biophys. Acta 1335 (1997) 1-4). We investigated the mechanism of this phenomenon by comparing Synechococcus sp. PCC 7942 cells that had been treated with N-ethylmaleimide (NEM) in order to inhibit electronic excitation transfers from phycobilisomes (PBS) to Chlas of PSI (A.N. Glazer, Y.M. Gindt, C.F. Chan, K. Sauer, Photosynth. Res. 40 (1994) 167-173) with untreated control cells. The NEM-treated cells were indistinguishable from the control cells with regard to PSII-dependent oxygen evolution, reduction of post-PSII oxidants, and osmotically induced volume changes, but differed in the following properties: (i) they could not photoreduce post-PSI electron acceptors; (ii) they diverted more PBS excitation to PSII; (iii) the rise of Chla fluorescence upon light acclimation of darkened (state 2) cells was smaller; and (iv) the Chla fluorescence of light-acclimated (state 1) cells was insensitive to the cell suspension osmolality. These properties suggest that osmolality regulates the core-mediated excitation coupling between PBS and PSI, possibly by influencing mutual orientation and/or distance between core holochromes (ApcE, ApcD) and PSI holochromes. Thus, in hyper-osmotic suspension, PBS deliver more excitation to PSI (hence less to PSII); in hypo-osmotic cell suspension they deliver less excitation to PSI (hence more to PSII).

State youth-access tobacco control policies and youth smoking behavior in the United States.

CONTEXT: State policies aimed at controlling youth access to tobacco are an important component of public health efforts to reduce smoking prevalence among youth and prevent subsequent disease. OBJECTIVES: This study sought to assess the extensiveness of state youth access tobacco control legislation in the United States, describe how state policies changed over a 4-year period, explore how various political and economic characteristics are related to state policies, and determine the relationship of youth smoking behavior to state youth tobacco control policies. DESIGN: This descriptive and correlational study utilized data from multiple national surveillance, economic, and sociodemographic data sets. PARTICIPANTS: All 50 states and the District of Columbia provided economic and political data. A standard tobacco-control policy score was developed by an expert panel for each state. Aggregated state-level measures of youth smoking behavior were provided by 79,491 youth in 33 states and the District of Columbia. MAIN OUTCOME MEASURES: Included were extent of state tobacco control policies and changes over time, relationship between state political and economic characteristics and tobacco control policies, and relationship between state policies and youth smoking behavior. RESULTS: State policy scores increased in variability and in mean value over the 4-year period, from a mean score of 7.2 in 1993 to 9.0 in 1996. State policy scores were significantly correlated with several state political and economic variables. States with more extensive tobacco control policies had significantly lower youth smoking rates. There was some evidence that a strong state tobacco economy may limit the effectiveness of tobacco control policies on youth smoking rates. CONCLUSIONS: It is possible to reliably measure the extent to which states are achieving important public health goals in limiting youth access to tobacco products. Comprehensive state tobacco control policies are important for increasing prevention and cessation of smoking among youth.

TNF-alpha induction by LPS is regulated posttranscriptionally via a Tpl2/ERK-dependent pathway.

Tpl2 knockout mice produce low levels of TNF-alpha when exposed to lipopolysaccharide (LPS) and they are resistant to LPS/D-Galactosamine-induced pathology. LPS stimulation of peritoneal macrophages from these mice did not activate MEK1, ERK1, and ERK2 but did activate JNK, p38 MAPK, and NF-kappaB. The block in ERK1 and ERK2 activation was causally linked to the defect in TNF-alpha induction by experiments showing that normal murine macrophages treated with the MEK inhibitor PD98059 exhibit a similar defect. Deletion of the AU-rich motif in the TNF-alpha mRNA minimized the effect of Tpl2 inactivation on the induction of TNF-alpha. Subcellular fractionation of LPS-stimulated macrophages revealed that LPS signals transduced by Tpl2 specifically promote the transport of TNF-alpha mRNA from the nucleus to the cytoplasm.

Sodium chloride-induced volume changes of freshwater cyanobacterium Synechococcus sp. PCC 7942 cells can be probed by chlorophyll a fluorescence.

Freshwater species of the cyanobacterial genus Synechococcus import NaCl passively, and export Na(+) actively, by means of primary and secondary extrusion mechanisms. As a result of the ion and water fluxes, cell volumes are enlarged. We show in this paper that the NaCl-induced volume enlargement of Synechococcus sp. PCC 7942 cells is attended by a rapid (k = 0.39 s(-1)) increase in chlorophyll (Chl) a fluorescence. The cell turgor threshold (measured by osmotic titration of Chl a fluorescence) was lower in the absence of NaCl (0.195 Osm kg(-1)) than in the presence of 0.4 M NaCl (0.248 Osm kg(-1)) indicating NaCl uptake by the cells. Turgor thresholds of cells suspended in NaCl-containing medium were enlarged further by protonophoric uncouplers, P-type ATPase inhibitors, and light starvation, conditions that are known to interfere with the active extrusion of Na(+) ions. Cell swelling exerts probably a regulation on the distribution of phycobilisome (PBS) excitation between photosystem II (fluorescent Chl a) and photosystem I (nonfluorescent Chl a), since it affects PBS-sensitized Chl a fluorescence, but not directly excited Chl a fluorescence. The dependence of the Chl a fluorescence of cyanobacteria on cell volumes allows probing of bioenergetic phenomena that are related to dynamic osmotic volume changes, transmembrane solute and water fluxes, plasma membrane permeabilities, and internal osmotic conditions of cyanobacterial cells. Thus, cyanobacteria may serve as quite convenient models of aquatic microorganisms in experimental studies directed toward the elucidation of perception mechanisms and defense mechanisms of water and solute stresses.

Artifacts in the assay of maize leaf phosphoenolpyruvate carboxylase activity due to its instability.

When the assay of maize leaf phosphoenolpyruvate carboxylase (EC 4.1.1.31) activity is started with phosphoenolpyruvate, much lower reaction rates are obtained as compared to the enzyme-initiated reaction. The difference is due to the lability of the dilute enzyme in the absence of its substrate and is increased with incubation time in the absence of substrate or stabilizers. The activation of the enzyme by glucose-6-phosphate is overestimated with the substrate-initiated assay since a part of the apparent activation is due to stabilization of the enzymic activity by this effector during the minus-substrate preincubation. In contrast, the inhibitory effect of malate is underestimated when the reaction is started with the substrate. The enzyme-initiated assay is recommended provided that the necessary corrections for apparent activity in the absence of substrate and for inactivation during the assay at low substrate levels are made.