Transmission of Vibrio cholerae Is Antagonized by Lytic Phage and Entry into the Aquatic Environment

Cholera outbreaks are proposed to propagate in explosive cycles powered by hyperinfectious Vibrio cholerae and quenched by lytic vibriophage. However, studies to elucidate how these factors affect transmission are lacking because the field experiments are almost intractable. One reason for this is that V. cholerae loses the ability to culture upon transfer to pond water. This phenotype is called the active but non-culturable state (ABNC; an alternative term is viable but non-culturable) because these cells maintain the capacity for metabolic activity. ABNC bacteria may serve as the environmental reservoir for outbreaks but rigorous animal studies to test this hypothesis have not been conducted. In this project, we wanted to determine the relevance of ABNC cells to transmission as well as the impact lytic phage have on V. cholerae as the bacteria enter the ABNC state. Rice-water stool that naturally harbored lytic phage or in vitro derived V. cholerae were incubated in a pond microcosm, and the culturability, infectious dose, and transcriptome were assayed over 24 h. The data show that the major contributors to infection are culturable V. cholerae and not ABNC cells. Phage did not affect colonization immediately after shedding from the patients because the phage titer was too low. However, V. cholerae failed to colonize the small intestine after 24 h of incubation in pond water—the point when the phage and ABNC cell titers were highest. The transcriptional analysis traced the transformation into the non-infectious ABNC state and supports models for the adaptation to nutrient poor aquatic environments. Phage had an undetectable impact on this adaptation. Taken together, the rise of ABNC cells and lytic phage blocked transmission. Thus, there is a fitness advantage if V. cholerae can make a rapid transfer to the next host before these negative selective pressures compound in the aquatic environment

Modeling Hong Kong real estate prices

This paper attempts to estimate real estate prices from a Hong Kong perspective. A hedonic price model is estimated utilizing housing transaction data during a period of relatively stable property price movements. Empirical results suggest that while a residential property of larger size, higher floor level, and better view commands a higher transaction price, a property lying closer to the mass transit railway station also commands a price premium. The nonlinear effect of floor level has also been confirmed to exert an impact upon prices. Furthermore, an apartment located on an "unlucky number" floor is not preferred by homebuyers and is usually transacted at a price discount. © Springer Science+Business Media B.V. 2007.Link_to_subscribed_fulltex

Health related quality of life after percutaneous coronary revascularisation in patients with previous coronary artery bypass grafts: A two-year follow up study

Percutaneous coronary revascularisation [PCR] improves angina and health related quality of life [HRQOL] compared to standard medical therapy. It is unknown whether PCR has the same benefits for patients with a history of CABG. Over a period of 5 years, we assessed HRQOL of patients undergoing PCR using Part 1 of the Nottingham Health Profile [NHP] at baseline 3, 12 and 24 months. We compared HRQOL after PCR in 255 patients with CABG to 2680 without. There were more males [81.1% v 69.6% p = 0.002] and older patients [mean age 60.1 years v. 58.0 p = 0.03] in CABG group. Perceived HRQOL improved at 24 months for pain, energy and emotional reaction but the improvement was less in the CABG group. However, mean NHP scores at 24 months for those with CABG had returned to baseline levels for sleep [34.9] and for physical function was worse than at baseline [22.0 vs 30.7]. This relationship persisted after adjustment for male sex, history of previous MI and coronary stent usage. Patients with previous CABG had less improvement in HRQOL after PCR. Further work is needed to assess the benefits and cost effectiveness of PCR in these patients