Using Stool Antigen to Screen for Helicobacter pylori in Immigrants and Refugees from High Prevalence Countries Is Relatively Cost Effective in Reducing the Burden of Gastric Cancer and Peptic Ulceration

Objectives

Refugees and immigrants from developing countries settling in industrialised countries have a high prevalence of Helicobacter pylori (H. pylori). Screening these groups for H. pylori and use of eradication therapy to reduce the future burden of gastric cancer and peptic ulcer disease is not currently recommended in most countries. We investigated whether a screening and eradication approach would be cost effective in high prevalence populations.

Methods

Nine different screening and follow-up strategies for asymptomatic immigrants from high H. pylori prevalence areas were compared with the current approach of no screening. Cost effectiveness comparisons assumed population prevalence''s of H. pylori of 25%, 50% or 75%. The main outcome measure was the net cost for each cancer prevented for each strategy. Total costs of each strategy and net costs including savings from reductions in ulcers and gastric cancer were also calculated.

Results

Stool antigen testing with repeat testing after treatment was the most cost effective approach relative to others, for each prevalence value. The net cost per cancer prevented with this strategy was US$111,800 (assuming 75% prevalence), $132,300 (50%) and $193,900 (25%). A test and treat strategy using stool antigen remained relatively cost effective, even when the prevalence was 25%.

Conclusions

H. pylori screening and eradication can be an effective strategy for reducing rates of gastric cancer and peptic ulcers in high prevalence populations and our data suggest that use of stool antigen testing is the most cost effective approach.     

Pore positioning: Current concepts in Pannexin channel trafficking

Pannexins (Panxs) are a multifaceted family of ion and metabolite channels that play key roles in a number of physiological and pathophysiological settings. These single membrane large-pore channels exhibit a variety of tissue, cell type, and subcellular distributions. The lifecycles of Panxs are complex, yet must be understood to accurately target these proteins for future therapeutic use. Here we review the basics of Panx function and localization, and then analyze the recent advances in knowledge regarding Panx trafficking. We examine several intrinsic features of Panxs including specific post-translational modifications, the divergent C-termini, and oligomerization, all of which contribute to Panx anterograde transport pathways. Further, we examine the potential influence of extrinsic factors, such as protein-protein interactions, on Panx trafficking. Finally, we highlight what is currently known with respect to Panx internalization and retrograde transport, and present new data illustrating Panx1 internalization following an activating stimulus.     

An improved way to determine nitrogen fertiliser requirements of sugarcane crops to meet global environmental challenges

Nitrogen (N) fertiliser management is increasingly important in sugarcane production as imperatives to reduce environmental impacts of N escalate. In this paper we report testing of a new concept for N management in sugarcane, the N Replacement system. This system relies on soil N cycling to ??buffer?? differences in crop N needs and N fertiliser supply to individual crops, and aligns N applications with actual cane production over the longer-term rather than potential production. In 11 experiments, conducted in a wide range of environments over two to five crops, cane and sugar yields in the N Replacement treatment were similar to those achieved with the farmers?? conventional N management, with a trend over successive crops for yields to increase relative to conventional management. At sites where experiments ran for at least 4 years, this trend resulted in cumulative sugar yields being higher in the N Replacement treatment. Average N applications were 35% lower in the N Replacement treatment, and N lost to the environment was estimated to be ??50% lower. Soil N ??buffering?? was adequate to maintain sufficient N supply to crops even when yields were up to 30% greater than expected. Thus, it is not necessary to align fertiliser applications to potential sugarcane yields, which are rarely achieved in practice. Our results show that the ecologically-based N Replacement system has promise to deliver superior environmental outcomes without significantly reducing production of sugarcane, and potentially other semi-perennial crops, in the tropics and subtropics. Further evaluation of the system will be beneficial, and there is scope for determining more site-specific values of parameters in the system. However, care must be taken to evaluate the system over sufficient time frames (e.g. >2 crops) so that productivity improvement trends in the N Replacement system can be expressed.     

Effect of tunicamycin on in vitro ripening of tomato pericarp tissue

Ripening of pericarp tissue from mature green, early breaker and late breaker stages of tomato ( Lycopersicon esculentum Mill. cv. Dombito) fruit development was inhibitied by tunicamycin. Ripening was evaluated by lycopene accumulation, chlorophyll degradation, rate of ethylene production and cell wall-bound polygalacturonase (EC 3.2.1.15) activity. Maximum inhibition of these ripening parameters occurred at a treatment of 240 μ M tunicamycin for 2 h except for cell wall-bound polygalacturonase activity, which was greatly inhibited by concentrations of 12 μ tunicamycin or higher. Tunicamycin treatment at 120 μ M for 2 h inhibited the incorporation of [³H]-mannose into macromolecules (about 70%) and pronase-sensitive material (about 65%) and the incorporation of [³H]-leucine into proteins (about 20%). Our results indicate that protein glycosylation plays an important role in the ripening of tomato pericarp tissue.     

Biochemical basis of high-temperature inhibition of ethylene biosynthesis in ripening tomato fruits

Biggs, M. S., Woodson, W. R. and Handa, A. K. 1988. Biochemical basis of high-temperature inhibition of ethylene biosynthesis in ripening tomato fruits. Physiol. Plant. 72: 572578
Incubation of fruits of tomato ( Lycopersicon esculentum Mill. cv. Rutgers) at 34°C or above resulted in a marked decrease in ripening-associated ethylene production. High temperature inhibition of ethylene biosynthesis was not associated with permanent tissue damage, since ethylene production recovered following transfer of fruits to a permissive temperature. Determination of pericarp enzyme activities involved in ethylene biosynthesis following transfer of fruits from 25°C to 35 or 40°C revealed that 1-aminocyclopropane-l-carboxylic acid (ACC) synthase (EC 4.4.1.14) activity declined rapidly while ethylene forming enzyme (EFE) activity declined slowly. Removal of high temperature stress resulted in more rapid recovery of ACC synthase activity relative to EFE activity. Levels of ACC in pericarp tissue reflected the activity of ACC synthase before, during, and after heat stress. Recovery of ethylene production following transfer of pericarp discs from high to permissive temperature was inhibited in the presence of cycloheximide, indicating the necessity for protein synthesis. Ethylene production by wounded tomato pericarp tissue was not as inhibited by high temperature as ripening-associated ethylene production by whole fruits.     

Muscarinic-receptor functioning in tracheas from normal and ovalbumin-sensitive guinea pigs

Responses to bilateral vagal nerve stimulation, to field stimulation, and to exogenous methacholine and histamine were compared in tracheas isolated from (a) saline injected (i.p.) and saline-aerosol exposed guinea pigs (control), (b) ovalbumin-sensitized and saline-aerosol exposed (sensitized) guinea pigs, and (c) ovalbumin-sensitized and 2% ovalbumin-aerosol exposed (challenged) guinea pigs. Tracheal pressor responses (cmH2O; 1 cmH2O = 98.1 Pa) to nerve and field stimulation, and maximal responses to methacholine and histamine were significantly increased in animals from group c compared with groups a and b. Dose-response lines in response to the two agonists, expressed as percent maximal contraction, did not differ among the groups. The M1 antagonist pirenzepine (0.1-10 nM) selectively reduced responses to nerve stimulation in all three groups. The M2 antagonist gallamine potentiated responses to nerve or field stimulation in all three groups. We conclude that M1, M2, and M3 muscarinic receptor functioning is similar in control and ovalbumin-sensitized guinea pigs. Changes in post-receptor transduction mechanisms may mediate the increased responsiveness noted in animals from group c.