The Return Trip Is Felt Shorter Only Postdictively: A Psychophysiological Study of the Return Trip Effect

The return trip often seems shorter than the outward trip even when the distance and actual time are identical. To date, studies on the return trip effect have failed to confirm its existence in a situation that is ecologically valid in terms of environment and duration. In addition, physiological influences as part of fundamental timing mechanisms in daily activities have not been investigated in the time perception literature. The present study compared round-trip and non-round-trip conditions in an ecological situation. Time estimation in real time and postdictive estimation were used to clarify the situations where the return trip effect occurs. Autonomic nervous system activity was evaluated from the electrocardiogram using the Lorenz plot to demonstrate the relationship between time perception and physiological indices. The results suggest that the return trip effect is caused only postdictively. Electrocardiographic analysis revealed that the two experimental conditions induced different responses in the autonomic nervous system, particularly in sympathetic nervous function, and that parasympathetic function correlated with postdictive timing. To account for the main findings, the discrepancy between the two time estimates is discussed in the light of timing strategies, i.e., prospective and retrospective timing, which reflect different emphasis on attention and memory processes. Also each timing method, i.e., the verbal estimation, production or comparative judgment, has different characteristics such as the quantification of duration in time units or knowledge of the target duration, which may be responsible for the discrepancy. The relationship between postdictive time estimation and the parasympathetic nervous system is also discussed.     

Psychophysiological Patterns During Cell Phone Text Messaging: A Preliminary Study

This study investigated the psychohysiological patterns associated with cell phone text messaging (texting). Twelve college students who were very familiar with texting were monitored with surface electromyography (SEMG) from the shoulder (upper trapezius) and thumb (abductor pollicis brevis/opponens pollicis); blood volume pulse (BVP) from the middle finger, temperature from the index finger, and skin conductance (SC) from the palm of the non-texting hand; and respiration from the thorax and abdomen. The counter-balanced procedure consisted of a 2 min pre-baseline, 1 min receiving text messages, 2 min middle baseline, 1 min sending text messages and 2 min post-baseline. The results indicated that all subjects showed significant increases in respiration rate, heart rate, SC, and shoulder and thumb SEMG as compared to baseline measures. Eighty-three percentage of the participants reported hand and neck pain during texting, and held their breath and experienced arousal when receiving text messages. Subjectively, most subjects were unaware of their physiological changes. The study suggests that frequent triggering of these physiological patterns (freezing for stability and shallow breathing) may increase muscle discomfort symptoms. Thus, participants should be trained to inhibit these responses to prevent illness and discomfort.     

Short Sleep Duration Is Associated with Shorter Telomere Length in Healthy Men: Findings from the Whitehall II Cohort Study

Background

Shorter telomere length and poor sleep are more prevalent at older ages, but their relationship is uncertain. This study explored associations between sleep duration and telomere length in a sample of healthy middle and early old age people.

Methods

Participants were 434 men and women aged 63.3 years on average drawn from the Whitehall II cohort study. Sleep duration was measured by self-report.

Results

There was a linear association between sleep duration and leukocyte telomere length in men but not in women (P = 0.035). Men reporting shorter sleep duration had shorter telomeres, independently of age, body mass index, smoking, educational attainment, current employment, cynical hostility scores and depressive symptoms. Telomeres were on average 6% shorter in men sleeping 5 hours or fewer compared with those sleeping more than 7 hours per night.

Conclusion

This study adds to the growing literature relating sleep duration with biomarkers of aging, and suggests that shortening of telomeres might reflect mechanisms through which short sleep contributes to pathological conditions in older men.     

Psychophysiological Assessment of Compulsive Gamblers' Arousal to Gambling Cues: A Pilot Study

Psychophysiological assessments measuring heart rate, systolic and diastolic blood pressure, and skin resistance level were conducted on 7 male compulsive gamblers and on 7 age and gender matched controls while both groups performed mental arithmetic and listened to individualized tapes of the gamblers' preferred form of gambling and an individualized fear tape. Heart rate responses of the gamblers to the 2 gambling audiotapes were significantly greater than those found for the controls whereas the groups did not differ on mental arithmetic or the fear provoking scene, confirming some degree of cue-specific arousal in gamblers. The other physical responses did not yield such strong results. If physiological arousal provides the motivational basis for gambling and is maintained on an intermittent schedule of reinforcement, the findings may have implications for the treatment of compulsive gambling.     

荒野之旅:赛罕乌拉

交通 1.北京、沈阳、石家庄、呼和浩特均有直达赤峰市首府红山区的航班。 2.大连经沈阳至赤峰、北京至赤峰、呼和浩特至赤峰、承德至赤峰均有火车可通达,呼和浩特至通辽火车在巴林右旗大板可乘降。 3.在赤峰换乘汽车行180公里至大板镇,然后再换乘汽车行110公里至赛罕乌拉。 住宿 1.保护区设有招待所,可接待40人,订房电话(0476)6172132,索布日嗄邮电宾馆标准间80元,可接待40人,订房电话(0476)6172177,六味神泉度假村,每床位40元。 2.在巴林右旗所在地大板镇还有二星级宾馆一家,标准间     

The Glycerol-3-Phosphate Permease GlpT Is the Only Fosfomycin Transporter in Pseudomonas aeruginosa

Fosfomycin is transported into Escherichia coli via both glycerol-3-phosphate (GlpT) and a hexose phosphate transporter (UhpT). Consequently, the inactivation of either glpT or uhpT confers increased fosfomycin resistance in this species. The inactivation of other genes, including ptsI and cyaA, also confers significant fosfomycin resistance. It has been assumed that identical mechanisms are responsible for fosfomycin transport into Pseudomonas aeruginosa cells. The study of an ordered library of insertion mutants in P. aeruginosa PA14 demonstrated that only insertions in glpT confer significant resistance. To explore the uniqueness of this resistance target in P. aeruginosa, the linkage between fosfomycin resistance and the use of glycerol-3-phosphate was tested. Fosfomycin-resistant (Fos-R) mutants were obtained in LB and minimal medium containing glycerol as the sole carbon source at a frequency of 10⁻⁶. However, no Fos-R mutants grew on plates containing fosfomycin and glycerol-3-phosphate instead of glycerol (mutant frequency, ≤5 × 10⁻¹¹). In addition, 10 out of 10 independent spontaneous Fos-R mutants, obtained on LB-fosfomycin, harbored mutations in glpT, and in all cases the sensitivity to fosfomycin was recovered upon complementation with the wild-type glpT gene. The analysis of these mutants provides additional insights into the structure-function relationship of glycerol-3-phosphate the transporter in P. aeruginosa. Studies with glucose-6-phosphate and different mutant derivatives strongly suggest that P. aeruginosa lacks a specific transport system for this sugar. Thus, glpT seems to be the only fosfomycin resistance mutational target in P. aeruginosa. The high frequency of Fos-R mutations and their apparent lack of fitness cost suggest that Fos-R variants will be obtained easily in vivo upon the fosfomycin treatment of P. aeruginosa infections.Pseudomonas aeruginosa is an opportunistic, life-threatening bacterial pathogen that especially affects critically ill patients in intensive care units or those suffering from chronic respiratory diseases such as cystic fibrosis (19, 40). Its 6.3-Mb genome supports its enormous metabolic versatility and, consequently, its adaptability to almost any challenging environment. One of the consequences of this versatility is the rapid adaptation to stressful environmental conditions, including starvation, desiccation, and antibiotic treatments (14, 40). Mutants resistant to one or several antibiotics will evolve during sufficiently prolonged treatments, this being a process facilitated by the presence of hypermutable alleles (31, 32). After years of treating cystic fibrosis patients with antibiotics, P. aeruginosa became unavoidably resistant to many or all of them (5). Multidrug-resistant strains of P. aeruginosa are an important problem for the treatment of nosocomial outbreaks and cystic fibrosis patients (27, 37). Currently, the treatment of multidrug-resistant P. aeruginosa requires the combination of various antimicrobial agents. Fosfomycin (Fos) has been reported to be effective in combination with other antipseudomonal agents (6, 29, 42, 44). The proportion of Fos-resistant (Fos-R) strains in clinical isolates of P. aeruginosa currently is not well known, and even the mechanisms that support Fos resistance in P. aeruginosa are not clear. Thus, the knowledge of the molecular bases involved in the development of spontaneous Fos resistance in P. aeruginosa is of particular interest.Fos is a unique broad-spectrum bactericidal antibiotic that is chemically unrelated to any other known antimicrobial agent used to treat urinary tract and gastrointestinal infections in humans (9, 35). It binds UDP-GlcNAc enol-pyruvyltransferase (MurA), acting as a phosphoenolpyruvate analogue and avoiding the formation of UDP-N-acetylglucosamine-3-O-enolpyruvate from UDP-N-acetylglucosamine and phosphoenolpyruvate (12, 33). Fos is taken up actively into bacterial cells via transport systems. In Escherichia coli, Fos is imported through two nutrient transport systems, the glycerol-3-phosphate (glycerol-3-P) transporter (GlpT) and glucose-6-phosphate (glucose-6-P) transporter (UhpT), to achieve its target and inhibits the initial step in cell wall synthesis (12, 17). The expression of these transport systems is induced by their substrates (glycerol-3-P and glucose-6P) and requires the presence of the cyclic AMP receptor protein (cAMP-CRP) complex (23, 30). Additionally, the high-level expression of UhpT requires the regulatory genes uhpA, uhpB, and uhpC (12, 30). Therefore, Fos-R strains isolated in E. coli contain mutations that prevent Fos transport using GlpT or UhpT (23, 30). Plasmid-encoded resistance also has been described previously (4, 41).In this paper, we describe the screening and analysis of Fos-R clones in a P. aeruginosa PA14 ordered insertional library (18). In addition, we studied the mutations responsible for the spontaneous resistance to Fos in P. aeruginosa PA14, the effect of these mutations on the in vitro growth rate, and the uniqueness of the mutational target.     

A Psychophysiological Study of Affective Disorders in Patients during Post-stroke Rehabilitation

Psychophysiological parameters of affective disorders (depression, depersonalization, and alexithymia) were studied in patients who had suffered ischemic stoke. Significant differences from healthy subjects were observed for certain MMPI scores and EEG, neurophysiological, and neuroimaging parameters. The results provide a basis for better understanding of brain function in healthy people and patients with dysfunction of higher cognitive processes.     

Only the Mature Form of the Plastidic Chorismate Synthase Is Enzymatically Active

Coding regions of a cDNA for precursor and mature chorismate synthase (CS), a plastidic enzyme, from Corydalis sempervirens were expressed in Escherichia coli as translational fusions to glutathione-S-transferase. Fusion proteins were purified, and precursor and mature forms of CS were then released by proteolytic cleavage with factor Xa. Although mature CS was enzymatically active after release, activity could be detected neither for the precursor CS nor for corresponding glutathione-S-transferase fusion proteins. In contrast, two other shikimate pathway enzymes (shikimate kinase and 5-enol-pyruvylshikimate-3-phosphate synthase) have previously been shown to be as enzymatically active as their respective higher molecular weight precursors. By expression of unfused, mature CS from C. sempervirens in E. coli, it was possible to obtain large quantities of enzymatically active CS protein compared to yields from plant cell cultures. Expression levels in E. coli approached 1% of total soluble protein. No differences were found between authentic CS isolated from cell cultures and CS expressed in and purified from E. coli, which made possible a more detailed biochemical characterization of CS. Quaternary structure analysis of the purified mature CS indicated that the enzyme exists as a dimer, in contrast to the active tetrameric structures determined for E. coli and Neurospora crassa enzymes.