A micro-Raman and X-ray study of erupted submarine pyroclasts from El Hierro (Spain) and its' astrobiological implications.

The pumice volcanic samples could have possible connections to the evolution of life and give us insight about their bio-geochemical processes related. In this regard, the samples from the volcanic eruption from La Restinga (El Hierro, Spain) in 2011 have been mainly studied by means of Raman spectroscopy. The research also includes analysis of XRD, Scanning Electron Microscopy and Optical Microscopy to support the Raman analysis. The results show that the Raman methods and mineral analyses are in strong agreement with the results obtained from other authors and techniques. The internal white foamy core (WFC) of the studied pumice samples shows amorphous silica, Fe-oxides, Ti-oxides, quartz, certain sulfates, carbonates, zeolites and organics. On the other hand, the external part (dark crust - DC) of these samples mainly presents primary-sequence mineralogy combined with some secondary alteration minerals such as olivine, feldspar, pyroxene, amorphous silica, and Fe-oxide. Raman spectroscopy detected other minerals not yet reported on these samples like barite, celestine and lepidocrocite. Also, the different chemometric and calibration methods for Raman spectroscopy in elemental composition, mineral classification and structural characterization has been successfully applied. From the astrobiological perspective, the research was also complemented with comparisons to other similar samples from terrestrial analogs. The main consideration was taking into account the proposed hypothesis regarding the potential behavior of the pumice as a substrate for the evolution of life. Furthermore, the detailed analysis from La Restinga eruption is coherent with the mineral phases and processes discussed from previous literature. The white internal part fulfills the conditions to work as an organic reservoir, confirmed by the detection of organic matter and selected minerals that could be used as energy sources for bacterial communities. The external layers of the samples work as a shielding layer to protect the organics from decay in extreme conditions. Finally, here we have demonstrated that the characteristics and advantages of Raman spectroscopy could help to assess and understand the possible biogenicity and alteration processes of any geological sample to be found on Mars.

Sex hormones play a role in vulnerability to sleep loss on emotion processing tasks.

The central aim of this study was to investigate hormones as a predictor of individual vulnerability or resiliency on emotion processing tasks following one night of sleep restriction. The restriction group was instructed to sleep 3 a.m.-7 a.m. (13 men, 13 women in follicular phase, 10 women in luteal phase of menstrual cycle), and a control group slept 11 p.m.-7 a.m. (12 men, 12 follicular women, 12 luteal women). Sleep from home was verified with actigraphy. Saliva samples were collected on the evening prior to restriction, and in the morning and afternoon following restriction, to measure testosterone, estradiol, and progesterone. In the laboratory, event-related potentials (ERPs) were recorded during presentation of images and faces to index neural processing of emotional stimuli. Compared to controls, sleep-restricted participants had a larger amplitude Late Positive Potential (LPP) ERP to positive vs neutral images, reflecting greater motivated attention towards positive stimuli. Sleep-restricted participants were also less accurate categorizing sad faces and exhibited a larger N170 to sad faces, reflecting greater neural reactivity. Sleep-restricted luteal women were less accurate categorizing all images compared to control luteal women, and progesterone was related to several outcomes. Morning testosterone in men was lower in the sleep-restricted group compared to controls; lower testosterone was associated with lower accuracy to positive images, a greater difference between positive vs neutral LPP amplitude, and lower accuracy to sad and fearful faces. In summary, women higher in progesterone and men lower in testosterone were more vulnerable to the effects of sleep restriction on emotion processing tasks. This study highlights a role for sex and sex hormones in understanding individual differences in vulnerability to sleep loss.

Impact of total sleep deprivation on behavioural neural processing of emotionally expressive faces.

Sleep deprivation impacts subjective mood states, but very little research has examined the impact on processing emotional information. In the current study, we investigated the impact of total sleep deprivation on neural responses to emotional facial expressions as well as the accuracy and speed with which these faces were categorized. Forty-nine participants completed two tasks in which they were asked to categorize emotional facial expressions as Happy, Sad, Angry, or Fearful. They were shown the 'full' expression of the emotions in one task and more subtle expressions in a second task in which expressions were 'morphed' with neutral faces so that the intensity of emotion varied. It was expected that sleep deprivation would lead to greater reactivity (indexed by larger amplitude N170 event-related potentials), particularly for negative and more subtle facial expressions. In the full face task, sleep-deprived (SD) participants were significantly less accurate than controls (C) at identifying Sad faces and slower to identify all emotional expressions. P1 was smaller and N170 was larger for the SD compared to C group, but for all emotions, indicating generalized impairment in low-level visual processing. In the more difficult morphed face task, SD participants were less accurate than C participants for Sad faces; as well, the group difference in reaction time was greatest for Sad faces. For the SD group, N170 increased in amplitude with increasing perceptual difficulty for the Fearful and Angry faces, but decreased in amplitude with increasing difficulty for Sad faces. These data illustrate that sleep deprivation led to greater neural reactivity for the threat-related negative emotions as they became more subtle; however, there was a failure to engage these perceptual resources for the processing of Sad faces. Sleep loss preferentially impacted the processing of Sad faces; this has widespread implications for sleep-deprived groups.

Workplace support for employees with cancer.

OBJECTIVE: The aim of the present study was to survey human resources personnel about how their northeastern Ontario workplaces assist employees with cancer. STUDY DESIGN AND SETTING: This cross-sectional study was conducted from December 2007 to April 2008. Surveys were sent to 255 workplaces in northeastern Ontario with 25 or more employees, and 101 workplaces responded (39.6% response rate). Logistic regression modelling was used to identify factors associated with more or less workplace support. More or less workplace support was defined by provision of paid time to employees with medical appointments and an offer of a return-to-work meeting and reduced hours for employees with cancer. Factors considered in the model included organization size, geographic location (urban, rural), and workplace type (private sector, public sector). RESULTS: Most of the human resources staff who completed the surveys were women (67.4%), and respondents ranged in age from 25 to 70 years (mean: 45.30 +/- 8.10 years). Respondents reported working for organizations that ranged in size from 25 to more than 9000 employees. In the logistic regression model, large organization size [odds ratio (or): 6.97; 95% confidence interval (ci): 1.34 to 36.2] and public sector (or: 4.98; 95% ci: 1.16 to 21.3) were associated with employer assistance. Public sector employers provided assistance at a rate 5 times that of private sector employers, and large organizations (>50 employees) provided assistance at a rate 7 times that of smaller organizations. CONCLUSIONS: In the population studied, employees with cancer benefit from working in larger and public sector organizations. The data suggest a need for further support for employees with cancer in some other organizations.

Sleep spindles and learning potential.

The number of sleep spindles remains relatively stable within individuals from night to night. However, there is little explanation for the large interindividual differences in spindles. The authors investigated the relationship between spindles and intelligence quotient (IQ) in 3 separate studies. The number of spindles and sigma power were positively correlated with performance IQ (PIQ), but not verbal IQ (VIQ). The perceptual/analytical skills measured by the PIQ Picture Completion subscale accounted for most of the interindividual differences in spindles. Furthermore, there was a relationship between the rapid eye movements (REMs) of REM sleep and VIQ in individuals with higher IQ scores. A similar pattern was observed between spindles and PIQ. It was hypothesized that high-IQ individuals have more spindles that can support more complex cortical networks underlying perceptual/analytical abilities.

Perineural invasion is associated with increased relapse after external beam radiotherapy for men with low-risk prostate cancer and may be a marker for occult, high-grade cancer.

PURPOSE: To investigate the risk of postradiotherapy prostate-specific antigen (PSA) failure on the basis of pretreatment risk factors in prostate cancer patients with and without perineural invasion (PNI) in prostate biopsy specimens and to explain the observation that otherwise low-risk patients with PNI experience decreased freedom from PSA failure after external beam radiotherapy (RT). METHODS AND MATERIALS: The study cohort consisted of 381 patients who underwent RT between 1989 and 2000 for clinically localized prostate cancer. A single genitourinary pathologist scored the absence or presence of PNI on all prostate biopsy specimens. Patients were divided into low-, intermediate- and high-risk subgroups on the basis of their 1992 American Joint Committee on Cancer T-stage, pretreatment PSA level, and Gleason score. Cox regression uni- and multivariate analyses were performed to evaluate whether the presence or absence of PNI in the biopsy specimen was a predictor of the time to post-RT PSA failure for patients in each pretreatment risk group. PSA failure was defined using the American Society for Therapeutic Radiology and Oncology consensus definition. Actuarial PSA failure-free survival was estimated using the Kaplan-Meier method, and comparisons were performed using the log-rank test. RESULTS: Cox regression univariate analysis revealed that PNI was a significant predictor of the time to PSA failure in the low-risk (p = 0.04) and high-risk (p = 0.03) cohorts. The 5-year PSA failure-free survival rate was 50% vs. 80% (p = 0.04) in low-risk patients, 70% vs. 75% (p = 0.72) in intermediate-risk patients, and 29% vs. 53% (p = 0.03) in high-risk patients with and without PNI, respectively. Cox regression multivariate analysis within the high-risk group revealed that a PSA level > or =20 ng/mL (p = 0.01) and Gleason score > or =8 (p = 0.02), but not PNI, were the only significant predictors of the time to PSA failure after RT. However, an association was found between the presence of PNI in the needle biopsy specimen and a biopsy Gleason score of 8-10 (p = 0.06). The association was stronger between the presence of PNI in the needle biopsy specimen and a biopsy Gleason score of 7-10 (p = 0. 033). CONCLUSION: A decrement in PSA outcome after RT for low-risk patients with PNI-positive biopsy specimens was found. The association between PNI and high Gleason score provides a possible explanation for the loss of statistical significance of PNI in the Cox regression multivariate analysis of the high-risk cohort. The data suggest that PNI found in the biopsy specimen of an otherwise low-risk patient predicts for occult high-grade disease that is missed owing to the sampling error associated with prostate biopsy. The association between PNI and a high Gleason score argues for the use of more aggressive therapy, such as hormonal therapy with RT and/or dose escalation, in these select patients.

Neurophysiological evidence for the detection of external stimuli during sleep.

STUDY OBJECTIVES: A cognitive evoked potential, labelled "P300," is elicited when an observer attends to and detects an infrequently delivered "target" stimulus. It is not typically present if the target is ignored or undetected. P300 is therefore thought to reflect some aspect of consciousness of the stimulus. There has been much controversy concerning whether P300 can be recorded in sleep, a state in which information processing of external events is presumably reduced. The present study investigated the effects of both pitch and intensity stimuli on information processing, in order to determine whether a more salient stimulus might elicit a P300 in sleep that is comparable to the waking P300. DESIGN: A true P300 will have a parietal maximum peak following a rare stimulus, and its amplitude will vary inversely with the probability of stimulus delivery. Participants were thus randomly assigned to one of three probability groups, in which the deviant was presented on 20%, 10%, or 5% of trials. SETTING: Data were collected in the Human Neurophysiology Laboratory at the University of Ottawa. PARTICIPANTS: Twenty-four young adults. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: During wakefulness, a parietal P300 was apparent following both pitch and intensity deviants when participants were asked to detect deviant stimuli. A P300 was also apparent following the intensity deviant when participants were instructed to ignore the stimuli. During non-REM sleep, no P300 could be identified. In REM sleep, very rare (p=.05) loud deviants elicited a parietal P300. This P300 was attenuated relative to the waking ignore condition. Moreover, the frontal dispersion of the peak was absent. CONCLUSIONS: These data provide evidence that participants are conscious (parietal P300) of very rare and intrusive stimuli during REM sleep, although the frontal aspects associated with this consciousness may be absent.

Exposure to pulsed high-frequency electromagnetic field during waking affects human sleep EEG.

The aim of the study was to investigate whether the electromagnetic field (EMF) emitted by digital radiotelephone handsets affects brain physiology. Healthy, young male subjects were exposed for 30 min to EMF (900 MHz; spatial peak specific absorption rate 1 W/kg) during the waking period preceding sleep. Compared with the control condition with sham exposure, spectral power of the EEG in non-rapid eye movement sleep was increased. The maximum rise occurred in the 9.75-11.25 Hz and 12.5-13.25 Hz band during the initial part of sleep. These changes correspond to those obtained in a previous study where EMF was intermittently applied during sleep. Unilateral exposure induced no hemispheric asymmetry of EEG power. The present results demonstrate that exposure during waking modifies the EEG during subsequent sleep. Thus the changes of brain function induced by pulsed high-frequency EMF outlast the exposure period.

Characterization of the sarcoplasmic reticulum k(+) and Ca(2+)-release channel-ryanodine receptor-in human atrial cells.

Since the role of sarcoplasmic reticulum (SR) in the E-C coupling of mammalian atrial cells has long been a subject of debate, biochemical, electrophysiological and immunological assays were performed in order to define and compare the properties of the Ca(2+)-release channel-ryanodine receptor (RyR)-from atrial and ventricular tissues. Cardiac SR preparations from human, canine and ovine tissues were compared using [(3)H]ryanodine binding, channel reconstitution into planar lipid bilayers and Western blot analysis involving RyR antibodies. [(3)H]ryanodine binding assays revealed a K(d)value of; 2.5 n M for all investigated cardiac tissues. Bound [(3)H]ryanodine was Ca(2+)-dependent with similar EC(50)values of 0.43, 0.49 and 0.79 microM for human atrium, canine ventricle and ovine atrium, respectively. However the density of binding sites was 4.5 times lower in atrial than in ventricular tissues. Beyond the presence of selective K(+)channels (gamma=188 pS) recorded in the SR enriched fraction of human atrium, the activity of a large conducting (gamma=671 pS) cationic channel was also observed. The latter displayed typical characteristics of Ca(2+)-release channels which were activated by 10 microM free [Ca(2+)] and 2 m M ATP. Western blot analysis revealed the presence of the RyR2 isoform in atrial and ventricular samples whereas no immunoreactivity was detected with specific RyR1 and RyR3 antibodies. Our results, obtained at the molecular level, are consistent with the presence of functional SR in human atrial cells. The human atrial Ca(2+)-release channel displays binding and regulating properties typical of the RyR2 isoform.

Endorectal magnetic resonance imaging as a predictor of biochemical outcome after radical prostatectomy in men with clinically localized prostate cancer.

PURPOSE: Endorectal magnetic resonance imaging (MRI) of the prostate is sometimes performed before radical prostatectomy but to our knowledge its role for predicting outcome after radical prostatectomy is not yet established. We evaluated the clinical usefulness of endorectal MRI for predicting time to prostate specific antigen (PSA) failure after radical prostatectomy in 1,025 consecutive men with clinically localized or PSA detected prostate cancer. Our analysis controlled for PSA level, biopsy Gleason score, clinical T stage and percent of positive biopsies. MATERIALS AND METHODS: Using Cox regression analysis we prospectively assessed time to PSA failure to determine the role of endorectal MRI in predicting PSA outcome after radical prostatectomy at our institution, where an expert prostate magnetic resonance radiologist is available. The main outcome measure was actuarial freedom from PSA failure. RESULTS: Endorectal MRI did not add clinically meaningful information in 834 of our 1,025 cases (81%) after accounting for the prognostic value of PSA, biopsy Gleason score, clinical T stage and percent of positive biopsies. However, this modality provided a clinically and statistically relevant stratification of 5-year PSA outcome in the remaining 191 patients at intermediate risk based on established prognostic factors. Specifically when endorectal MRI was interpreted as indicating extracapsular versus organ confined disease the relative risk of PSA failure was 3.6 (95% confidence interval 2.0 to 6.3), and 5-year actuarial freedom from PSA failure was 33% versus 72% (p <0.0001). CONCLUSIONS: Despite expert radiological interpretation endorectal MRI had potential clinical value in less than 20% of the cases in our study after accounting for established prognostic factors. While further study of the value of this modality for predicting clinical outcome after radical prostatectomy should be performed in this select cohort, routine use of endorectal MRI cannot be justified based on these data.

The role of the spindle in human information processing of high-intensity stimuli during sleep.

Sleep spindles are 12-14 Hz oscillations in EEG, which are thought to inhibit or 'gate' information processing. Event-related potentials may be employed to probe the extent of information processing during sleep. Previous research indicates that event-related potentials elicited by moderate intensity stimuli show increased positivity (or further removal of negativity) when stimuli are presented concurrent with spindles. However, the effectiveness of spindles to inhibit the processing of much louder stimuli remains unknown. The purpose of the present study was to investigate the extent of this gating, by using a range of stimuli including those that are loud and intrusive. Eight good sleepers were recorded during a single night. Auditory stimuli were delivered randomly at 0, 60, 80 or 100 dB SPL. Trials were sorted off-line by sleep stage, stimulus intensity and spindle characteristic (i.e. spindle absent, spindle present). During the sleep-onset period, the often-reported changes in event-related potentials were observed - N1 decreased and P2 increased in amplitude. In Stage 2 sleep, P2 was affected by the presence of spindles, particularly when stimulus intensity was loud. Its amplitude was greatest when spindles occurred following the onset of the stimulus. Scalp-recorded spindles might, therefore, be a consequence of the prior thalamic inhibition of information processing, especially when confronted by loud, intrusive external stimuli.

The effects of varying stimulus intensity on P300 during REM sleep.

Event-related potentials (ERPs) are often used to measure the extent of information processing during sleep. Previous studies have indicated that a late positive wave, P300, can be elicited during REM sleep if stimuli are very rare and/or very loud. The present study examined the role of stimulus intensity in eliciting a P300 during REM sleep. Eight subjects were presented with auditory tone pips with an intensity of either 0, 60, 80 or 100 dB SPL. Stimuli were delivered at random with equal probability. Trials were sorted by stage of sleep, stimulus intensity, and presence or absence of rapid eye movements in REM sleep. During the waking state, when subjects read a book, the loud 100 dB stimulus elicited short (P3a) and long latency (P300) positive waves (peaking at 293 and 373 ms respectively). In stage of 2 non-REM sleep, N1 decreased to baseline level while P2 increased in amplitude compared to the waking state. A P300 could not be observed in stage 2 sleep regardless of the level of stimulus intensity. During REM sleep, a late P300 (latency 363 ms) was elicited by the 100 dB stimulus. The earlier positive peak (i.e. P3a) was not apparent. The P300 was reduced in amplitude compared to the waking state. Its amplitude did not differ between phasic and tonic states of REM sleep. A late parietal negative slow wave (SW) was also apparent during REM. Although the SW was larger during phasic compared to tonic REM, the difference was not significant. These data suggest that stimuli which are sufficiently intrusive to elicit a P300 in the waking state continue to do so in REM sleep.

P300 to high intensity stimuli during REM sleep.

OBJECTIVES: The P300 component of the auditory event-related potential (ERP) is a large amplitude positive wave peaking at approximately 300 ms following detection of a rare significant stimulus. Although P300 is typically only evoked when the subject attends to the stimulus, it may also be elicited in an awake, inattentive subject if the stimulus is sufficiently intrusive. We therefore employed an oddball task to determine if high intensity stimuli would elicit the P300 during sleep. METHODS: A loud 90 dB SPL tone pip was presented infrequently (P = 0.05) in a train of lower intensity 70 dB SPL standard stimuli. A multiple channel EEG was recorded from 8 good sleepers during a single night. RESULTS: A large amplitude parieto-central P300, peaking at 321 ms, was apparent in REM sleep to the loud deviant stimulus. In stage two non-REM sleep, a later positive wave, peaking at 446 ms, was apparent even after K-Complexes were removed from the average. This non-REM P450 was however maximum over occipito-parietal areas of the scalp. CONCLUSION: The presence of a P300 in REM sleep following a loud, rare stimulus indicates that sensory discrimination capabilities remain intact during this state. This may be associated with either pre- or conscious processing of relevant stimuli.

Scalp topography of the auditory evoked K-complex in stage 2 and slow wave sleep.

During NREM sleep a very large amplitude wave-form, known as the K-complex, may be elicited upon presentation of an external stimulus. The present study compared the scalp distribution of a prominent negative wave peaking at about 550 ms and a later positive wave peaking between 900 and 1300 ms in stage 2 and slow wave sleep (SWS). Nine subjects spent a single night in the laboratory. They were presented with an 80 dB SPL 2000 Hz auditory tone pip every 15 s. The EEG was recorded from 29 electrode sites and referenced to the nose. A K-complex was elicited on 34% of trials in stage 2 and on 46% of trials in SWS. A negative wave peaking at 330 ms was larger on trials in which the K-complex was elicited than on trials in which it was not. The large amplitude N550 was readily observable on trials in which the K-complex was elicited but could not be observed on trials in which it was not. The N550 was bilaterally symmetrical and was maximum over fronto-central areas of the scalp in both stage 2 and SWS. It inverted in polarity at the mastoid and inferior parietal regions. The scalp distribution of N550 significantly differed between stage 2 and SWS. It showed a sharper decline in amplitude over parietal and posterior-inferior areas of the scalp in stage 2 compared to SWS. A later P900 was maximum over centro-frontal areas of the scalp and was also bilaterally symmetrical. It showed a significantly sharper decline in amplitude over widespread inferior areas during SWS. Because the scalp maps of the N550 and P900 are different in stage 2 and SWS, their intracranial sources must also be different.

The management of patients undergoing arterial reconstructive surgery.

Management of the patient undergoing arterial reconstructive surgery is multidisciplinary and challenging. It involves vigilant monitoring, early detection, and treatment of high frequency complications of the underlying disease process (atherosclerosis) and the diagnostic and surgical procedures for limb-threatening occlusive lesions. The purpose of this article is to address patterns of peripheral arterial disease, indications for surgery, types of surgical procedures, and expected outcomes. In addition, nursing care guidelines related to preoperative care, postoperative care, and discharge planning are provided.

Effect of bone density on body composition estimates in young adult black and white women.

Bone mineral content (BMC) and density (BMD) by dual x-ray absorptiometry, total body water (TBW) by the deuterium oxide (D2O) dilution technique, and body density (Bd) by hydrostatic weighing were measured in 26 black (B) and 26 white (W) young adult women. Both groups were similar in age, height, weight, and total skinfolds; however, black subjects had significantly higher BMC and BMD. Formulas to estimate percent body fat (%BF) from Bd included Siri's two-component equation for the reference man, which assumes a fat free body density (FFBd) of 1.100 g.ml-1, and an adjusted two-component formula that assumes a lower FFBd of 1.095 g.ml-1. Percent body fat was also predicted from TBW and by several multicomponent models that corrected for individual subject variation in measured BMC and TBW. The two groups did not differ significantly in %BF predictions by any of the methods. However, the difference in %BF between the groups was halved with the four-component model (B = 21.9%; W = 23.6%) as compared with that calculated from the Siri two-component densitometric model (B = 21.2%; W = 24.2%). Within each racial group, %BF was not significantly different when predicted by two-component or multicomponent models. However, %BF of individuals with the highest and lowest BMD was substantially under- and overpredicted, respectively, by Siri's equation.(ABSTRACT TRUNCATED AT 250 WORDS)

Can transcutaneous recordings detect gastric electrical abnormalities?

The ability of transcutaneous recordings of gastric electrical activity to detect gastric electrical abnormalities was determined by simultaneous measurements of gastric electrical activity with surgically implanted serosal electrodes and cutaneous electrodes in six patients undergoing abdominal operations. Transient abnormalities in gastric electrical activity were seen in five of the six patients during the postoperative period. Recognition of normal gastric electrical activity by visual analysis was possible 67% of the time and with computer analysis 95% of the time. Ninety four per cent of abnormalities in frequency were detected by visual analysis and 93.7% by computer analysis. Abnormalities involving a loss of coupling, however, were not recognised by transcutaneous recordings. Transcutaneous recordings of gastric electrical activity assessed by computer analysis can usually recognise normal gastric electrical activity and tachygastria. Current techniques, however, are unable to detect abnormalities in electrical coupling.

Colonic and anorectal motility in young women with severe idiopathic constipation.

Forty-four severely constipated women and 16 (8 female, 8 male) asymptomatic volunteers underwent assessment of colon function by (a) clinical examination, (b) rectosigmoid intraluminal pressure recording, (c) colonic transit utilizing radiopaque markers, (d) anorectal manometry, and (e) rectosigmoid electrical activity. Constipated patients were characterized by (a) a greater volume and pressure of rectal distention required for both sensation and sphincter relaxation, (b) diminished basal and postmorphine motility indices only in the distal rectum, (c) delayed transit, and (d) an empty rectum when severely constipated. A neural abnormality affecting afferent nerves may be present in the rectum of female patients with severe idiopathic constipation. Delivery of stool to the rectum is impaired in these patients.