Dynamics of motor nerve terminal remodeling unveiled using SNARE-cleaving botulinum toxins: the extent and duration are dictated by the sites of SNAP-25 truncation

Nerve sprouts emerge from motor nerve terminals following blockade of exo-endocytosis for more than 3 days by botulinum neurotoxin (BoNT), and form functional synapses, albeit temporary. Upon restoration of synaptic activity to the parent terminal 7 and 90 days after exposure to BoNT/F or A respectively, a concomitant retraction of the outgrowths was observed. BoNT/E caused short-term neuroparalysis, and dramatically accelerated the recovery of BoNT/A-paralyzed muscle by further truncation of SNAP-25 and its replenishment with functional full-length SNARE. The removal of 9 C-terminal residues from SNAP-25 by BoNT/A leads to persistence of the inhibitory product due to the formation of a nonproductive SNARE complex(es) at release sites, whereas deletion of a further 17 amino acids permits replenishment and a speedy recovery. (C) 2003 Elsevier Science (USA). All rights reserved.

Effectiveness of hospital-based smoking cessation

Study objectives: Smoking cessation for current smokers is a health-care imperative. It is not clear which approaches to smoking cessation are the most effective in the hospital setting and which factors predict long-term abstinence. We hypothesized that a hospital-based smoking cessation program involving behavioral modification and support would provide an effective intervention for smoking cessation. Design: Prospective cohort study. Setting: Smoking cessation clinics in a tertiary referral, cardiothoracic hospital. Patients or participants: Two hundred forty-three smokers and 187 never-smoker control subjects. Interventions: Smokers underwent specific sessions of individual counseling on behavioral modification, including written information, advice about quit aids, and support during the quit attempt. Abstinence was confirmed by exhaled carbon monoxide measurements. Measurements and results: Compared to never-smoker control subjects, smokers were more likely to have grown up with a smoking father or siblings, and to currently live or socialize with other smokers. Two hundred sixteen smokers attended at least two sessions of the smoking cessation program. Of these, 25% were unavailable for follow-up at 12 months and were assumed to be smoking. The point prevalence abstinence rate at 12 months was 32%. Independent factors associated with abstinence at 12 months were self-belief in quitting ability, having a heart condition, growing up without siblings who smoked, and increasing number of pack-years. Conclusions: This prospective study has demonstrated that this hospital-based smoking cessation program was as effective as programs in other settings. Social and psychological factors were associated with a greater chance of abstinence.

Transmission mode and distribution of parasites among groups of the social lizard Egernia stokesii

We explored patterns of infection of three apicomplexan blood parasites with different transmission mechanisms in 46 social groups across seven populations of the Australian lizard, Egernia stokesii. There was higher aggregation of infections within social groups for Hemolivia, transmitted by ticks, and Schellackia, either tick-transmitted or directly transmitted from mother to offspring, than for Plasmodium, with more mobile dipteran vectors. Prevalence was not related to group size, proximity to other groups or spatial overlap with adjacent groups for any of the parasites. However, for Hemolivia, groups with higher levels of relatedness among adults had higher parasite prevalence. Living in social groups leads to higher risk of infection for parasites with low transmission mobility. An unanswered question is why so few lizard species tolerate these risks to form stable social aggregations.