The Pseudomonas Quinolone Signal (PQS)

Pseudomonas aeruginosa is an opportunistic human pathogen that routinely appears near the top of public health threat lists worldwide. P. aeruginosa causes infections by secreting a wealth of exceptionally active exoproducts, leading to tissue damage. The synthesis of many of these virulence factors is now known to be under the control of the quorum sensing (QS) system. Over the last 15 years, the Pseudomonas quinolone signal (PQS) has been found to play a crucial role in QS by linking the two segments (las and rhl) of the P. aeruginosa N-acylhomoserine lactone-dependent QS signaling pathways. Herein, we present the discovery and elucidation of PQS signaling from a historical perspective, and also outline some of the outstanding research questions that still need to be addressed. Finally, we show how a better understanding of the biochemistry underpinning this pathway is leading to the development of new antimicrobial interventions with clear therapeutic potential.     

The Presence of Hyperlinks on Social Network Sites: A Case Study of Cyworld in Korea

A study was conducted to determine the extent to which hyperlinks appear within user‐submitted comments on Korean social network service Cyworld. Links to social movements were common as was news stories regarding the bleak economic forecast. Males were found to post hyperlinks more frequently than females, and those politicians in the ruling party received more links than those in opposition parties. The purpose of posting a link was evaluated and tasks such as performing Message Amplification and Network Building were prominent. Natural‐language processing revealed primarily negative sentiment towards the governing president. The findings go some way to indicate how the presence of hyperlinks and short messages within online dialogs can provide an insight into public perception as a whole.     

Osmotic dehydration of apple slices with CaCl2 and sucrose limits decay caused by Penicillium expansum, Colletotrichum acutatum, and Botrytis cinerea and does not promote Listeria monocytogenes or total aerobic population growth.

The interaction of Penicillium expansum Link, Colletotrichum acutatum, and Botrytis cinerea Pers.:Fr. with Listeria monocytogenes on osmotically dehydrated apple slices was evaluated. In mineral analyses of the slices, the calcium content of the peel and flesh tissues increased by 4- and 11-fold, respectively, when processed in 2% CaCl2. These slices also exhibited less decay by P. expansum, C. acutatum, and B. cinerea. Inoculation of slices with P. expansum resulted in a decrease in the pH of the flesh tissue at the infection site, while the pHs of slices infected with C. acutatum and B. cinerea increased and remained stable, respectively. Total mold population increased in wounds inoculated with P. expansum or C. acutatum. The presence of L. monocytogenes in the wounds did not significantly affect mold growth. The association of P. expansum and L. monocytogenes on apple slices resulted in a decrease in the bacterial population, whereas L. monocytogenes survived when slices were inoculated with C. acutatum. When associated with B. cinerea, there was a fourfold decrease in the L. monocytogenes population when slices were treated with 2% CaCl2. The total aerobic population was not significantly affected by the type of microorganism added to the wounds or by the osmotic treatment. These data show that osmotic dehydration with 2% CaCl2 combined with 20% sucrose limits decay of apple slices and does not promote bacterial or total aerobic population growth.     

A capillary absorption spectrometer for stable carbon isotope ratio (13C∕12C) analysis in very small samples

A capillary absorption spectrometer (CAS) suitable for IR laser isotope analysis of small CO(2) samples is presented. The system employs a continuous-wave (cw) quantum cascade laser to study nearly adjacent rovibrational transitions of different isotopologues of CO(2) near 2307 cm(-1) (4.34 μm). This initial CAS system can achieve relative isotopic precision of about 10 ppm (13)C, or ～1 per thousand (per mil in delta notation relative to Vienna Pee Dee Belemnite) with 20-100 picomoles of entrained sample within the hollow waveguide for CO(2) concentrations ～400-750 ppm. Isotopic analyses of such gas fills in a 1-mm ID hollow waveguide of 0.8 m overall physical path length can be carried out down to ～2 Torr. Overall (13)C∕(12)C ratios can be calibrated to ～2 per thousand accuracy with diluted CO(2) standards. A novel, low-cost method to reduce cw-fringing noise resulting from multipath distortions in the hollow waveguide is presented, which allows weak absorbance features to be studied at the few ppm level (peak-to-rms) after 1000 scans are co-added in ～10 s. The CAS is meant to work directly with converted CO(2) samples from a laser ablation-catalytic combustion micro-sampler to provide (13)C∕(12)C ratios of small biological isolates currently operating with spatial resolutions ～50 μm.     

MUSICAL CRYPTOGRAPHY

Cipher Device M-94 was adopted by the United States Army in 1922, the same year papers found in the Library of Congress revealed that Thomas Jefferson had invented the same device about 125 years earlier. Almost 100 years after Jefferson, Commandant Etienne Bazeries, a French army cryptologist, independently developed a similar device. Both inventions, which ultimately formed the basis for the most widely used cryptosystems in the 20th century, apparently had a common antecedent in the letter lock, which was popularized in France by Edme Regnier during the late 18th and early 19th centuries.     

Comparison of flavor changes in cooked-refrigerated beef, pork and chicken meat patties

Beef and pork longissimus dorsi (LD) and semimembranosus (SM) and chicken breast (B) and thigh (T) muscles excised 24 h postmortem were ground by muscle/species group, formed into patties, pan-fried, refrigerated for 0, 3 or 6 days, and evaluated by a trained sensory panel for intensity of specific flavors. The rate of decline in species-specific natural meat flavor intensity and the rate of increase in "cardboard" (CBD) flavor intensity during the first half of the 6-day storage were fastest for beef, while such decline and increase during the entire storage period were slowest for chicken B. Overall trends of natural meat flavor and CBD intensity changes for chicken T appeared more like those for the red meats than chicken B. It was concluded that, while flavor deterioration can occur in cooked-stored meats from all the species, quantitative or the magnitude of differences between species would depend on muscle types and sensory terms/method used.     

The role of psychoneuroendocrine factors on spaceflight-induced immunological alterations

This paper summarizes previous in-flight infections and novel conditions of spaceflight that may suppress immune function. Granulocytosis, monocytosis, and lymphopenia are routinely observed following short duration orbital flights. Subtle changes within the monocyte and T cell populations can also be noted by flow cytometric analysis. The similarity between the immunological changes observed after spaceflight and other diverse environmental stressors suggest that most of these alterations may be neuroendocrine-mediated. Available data support the hypothesis that spaceflight and other environmental stressors modulate normal immune regulation via stress hormones, other than exclusively glucocorticoids. It will be essential to simultaneously collect in-flight endocrine, immunologic, and infectious illness data to determine the clinical significance of these results. Additional research that delineates the neuroendocrine mechanisms of stress-induced changes in normal immune regulation will allow clinicians in the future to initiate prophylactic immunomodulator therapy to restore immune competence altered by the stress of long-duration spaceflight and therefore reduce morbidity from infectious illness, autoimmune disease, or malignancy.     

Effect of sodium bicarbonate administration on renal function of horses

The use of clinical paths for patient care management was explored by this development team as a mechanism to provide consistent, high-quality care to hospitalized patients in high-volume, high-risk diagnostic categories. Reviewing the historical aspects and importance of clinical paths helped expand the team's perspective to incorporate pre- and posthospitalization phases of patient care into the clinical path being developed. A multidisciplinary team of physicians, nurses, health educators, and dietitians from both inpatient and outpatient departments of Kaiser-Santa Teresa Medical Center in San Jose, California, devised and implemented an Adult Diabetes Mellitus care path. Staff education preceded the implementation of the care paths. Measurements of quality indicators showed improvements in patient satisfaction, patient education, patient knowledge, and nutrition assessments.     

Relationship of climate and genotype to seasonal variation in the glucosinolate–myrosinase system. II. Myrosinase activity in ten cultivars of Brassica oleracea grown in fall and spring seasons

Myrosinase catalyzes the hydrolysis of glucosinolates found in the Brassicaceae, generating a variety of bioactive reaction products that may aid in the prevention of some cancers and that are suppressive to soil‐borne plant pathogens. Two cultivars each of broccoli (Brassica oleracea L var italica), Brussels sprouts (B oleracea var gemmifera), cabbage (B oleracea var capitata), cauliflower (B oleracea var botrytis), and kale (B oleracea var acephala) were grown during two fall seasons and two spring seasons to determine if myrosinase activity varied by season. Regression models that included mean temperature and photosynthetic photon flux (PPF) during the growing seasons showed that climatic variables explained seasonal differences for myrosinase activity. Activity‐FW (FW = fresh weight; U g^?1) and specific activity (U mg^?1) were significantly (p ≤ 0.05) affected by season, botanical group and group × season. Activity‐FW had a negative linear relationship with temperature, and a positive linear but negative quadratic relationship with PPF. Specific activity had a positive linear and a negative quadratic relationship with both temperature and PPF. Therefore the influence of climatic factors on myrosinase activity in Brassica species may affect the potential benefits of the glucosinolate–myrosinase system. Copyright © 2004 Society of Chemical Industry