Enantiomorphing Chiral Plasmonic Nanostructures:A Counterintuitive Sign Reversal of the Nonlinear Circular Dichroism

Plasmonic nanostructures have demonstrated a remarkable ability to control light in ways never observed in nature, as the optical response is closely linked to their flexible geometric design. Due to lack of mirror symmetry, chiral nanostructures allow twisted electric field “hotspots” to form at the material surface. These hotspots depend strongly on the optical wavelength and nanostructure geometry. Understanding the properties of these chiral hotspots is crucial for their applications; for instance, in enhancing the optical interactions with chiral molecules. Here, the results of an elegant experiment are presented: by designing 35 intermediate geometries, the structure is “enantiomorphed” from one handedness to the other, passing through an achiral geometry. Nonlinear multiphoton microscopy is used to demonstrate a new kind of double‐bisignate circular dichroism due to enantiomorphing, rather than wavelength change. From group theory, a fundamental origin of this plasmonic chiroptical response is proposed. The analysis allows the optimization of plasmonic chiroptical materials

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Effects of transmeridian transportation on plasma cortisol circadian and ultradian variations

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The effect of dexamethasone on the 24-hour profiles of adrenocorticotropin and cortisol in cushing’s syndrome

ACTH and cortisol are normally secreted episodically rather than continuously. This characteristic of episodic secretion is preserved in patients with Cushing's syndrome. To determine whether exogenous glucocorticoids modulate this pulsatility and to study its possible etiological implications, we obtained 24-h plasma cortisol profiles in seven patients with Cushing's syndrome (five Cushing's disease, one adrenal adenoma, and one bilateral adrenal cortical macronodular hyperpla-sia) before and during suppression with various doses of dexa-methasone [low (0.5 mg, every 6 h), high (2 mg, every 6 h), and very high (4 mg, every 6 h)]. Simultaneous 24-h plasma ACTH profiles were obtained in two patients with Cushing's disease. Blood was drawn at 30-min intervals for 25 h. Individual profiles were analyzed to determine the 24-h mean level, the presence of a circadian component and its amplitude, and the number and magnitude of significant secretory pulses over the 24-h span. The concordance between significant ACTH and cortisol pulses also was quantified. Baseline values in patients were compared o t those in seven normal subjects. Under basal conditions, the 24-h mean cortisol level was 3-t o 4-fold higher than normal in all patients with Cushing's syndrome. In contrast, the basal 24-h mean ACTH level was normal in one, and slightly elevated in the other of the two patients with Cushing's disease in whom plasma ACTH concentrations were measured. However, in contrast to the normal subjects, all ACTH values were above 10 pg/ml even during the period of minimal secretion. Basal circadian variation in adre-nocortical activity, albeit of reduced amplitude, was found in four of five patients with Cushing's disease; it was absent in the patient with adrenal adenoma. Low dose dexamethasone reduced the 24-h mean cortisol level and increased the amplitude of the circadian rhythm, unmasking a diurnal rhythm in the single patient with Cushing's disease in whom no significant circadian periodicity was present in the basal condition. This effect was further increased with the high dose of dexamethasone, which concomitantly reduced the number and increments of the secretory pulses. A lesser effect was found in the patient with bilateral nodular hyperplasia, and no effect was seen in the patient with adrenal adenoma. ACTH pulsatility, but not diurnal rhythm, also was dampened by dexamethasone. Reduction in the magnitude, but not the number, of ACTH secretory pulses by dexamethasone produced a reduced concordance ratio of ACTH with cortisol pulses of 0.39, compared to 0.64 in the basal state. The concordance ratios of cortisol with ACTH pulses remained unchanged (0.89 and 0.88) during the basal state and the administration of high doses of dexamethasone, respectively. These data indicate that during dexamethasone suppression, fewer of the low amplitude ACTH pulses elicit a significant cortisol response and that episodic cortisol secretion is ACTH induced. These data do not support the concept of a defect in the neural clock generating the 24-h periodicity in Cushing's disease. They suggest that the expression of the diurnal rhythm is masked, since it could be magnified and even uncovered by dexamethasone, in association with the reduction in the episodic pulsatility. In adrenal cortical macronodular hyperplasia, the low but persistent circadian variation in cortisol, obliterated by high dose dexamethasone, is in agreement with the postulated dual pituitary and adrenal etiology of this condition. © 1985 by The Endocrine Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Circadian and ultradian variations of ACTH and cortisol secretion

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Oscillations in Insulin Secretion During Constant Glucose Infusion in Normal Man: Relationship to Changes in Plasma Glucose

Peripheral plasma or serum concentrations of glucose, insulin, C-peptide, glucagon, and cortisol and insulin secretory rates (ISR) were determined at 15-min intervals in eight normal subjects during a constant iv infusion of 4.5 mg glucose/kg� min for a 24-h period. During each sampling interval, the secretory rate of insulin was calculated by deconvolution of the peripheral plasma C-peptide concentration using C-peptide kinetic parameters derived after bolus injections of C-peptide in individual subjects. Periodogram analysis of the individual glucose curves demonstrated a circadian rhythm in all subjects, with a major nocturnal acrophase occurring at an average clock time of 0228 h (range, 0045-0350 h). In five of the eight subjects, a minor acrophase occurred at an average time of 1774 h (range, 1530-2045 h). This diurnal variation in plasma glucose levels was not paralleled by a similar pattern in insulin secretion. Although glucose was infused at a constant rate, significant pulses were found in glucose, insulin, and C-peptide levels and ISR; the pulse durations of these parameters were 182 ± 30 (± SE), 89 ± 5, 100 ± 8, and 85 ± 5 min, respectively, and their periodicities were 208 ± 33, 106 ± 7, 114 ± 10, and 106 ± 7 min. The durations and frequencies for pulses of insulin, C-peptide, and ISR were not significantly different, whereas glucose pulses had a longer duration and were less frequent (P < 0.05, by analysis of variance). On the average, 54 ± 9% of the C-peptide pulses and 47 ± 8% of the ISR pulses were concomitant with a pulse in glucose levels. Moreover, approximately half of the Cpeptide and ISR pulses that were not concomitant with a glucose pulse occurred in synchrony with a shoulder on the up-stroke or down-stroke of glucose pulses. Analysis of glucagon and cortisol profiles revealed no significant associations with the insulin and glucose oscillations. In conclusion, during a constant glucose infusion in normal subjects, regular oscillations of insulin secretion occur at 80- to 120-min intervals. Their tight coupling with glucose oscillations and the lack of association with fluctuations of glucagon and cortisol suggest that these oscillations represent a dynamic property of the insulin-glucose feedback loop. (J Clin Endocrinol Metab 67: 307, 1988). © 1988 by The Endocrine Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Enantiomorphing Chiral Plasmonic Nanostructures:A Counterintuitive Sign Reversal of the Nonlinear Circular Dichroism

Plasmonic nanostructures have demonstrated a remarkable ability to control light in ways never observed in nature, as the optical response is closely linked to their flexible geometric design. Due to lack of mirror symmetry, chiral nanostructures allow twisted electric field "hotspots" to form at the material surface. These hotspots depend strongly on the optical wavelength and nanostructure geometry. Understanding the properties of these chiral hotspots is crucial for their applications; for instance, in enhancing the optical interactions with chiral molecules. Here, the results of an elegant experiment are presented: by designing 35 intermediate geometries, the structure is "enantiomorphed" from one handedness to the other, passing through an achiral geometry. Nonlinear multiphoton microscopy is used to demonstrate a new kind of double-bisignate circular dichroism due to enantiomorphing, rather than wavelength change. From group theory, a fundamental origin of this plasmonic chiroptical response is proposed. The analysis allows the optimization of plasmonic chiroptical materials.</p

Hormonal changes as a consequence of jet lag :corticotrophic axis

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Effects of 'jet lag' on hormonal patterns. I. Procedures, variations in total plasma proteins, and disruption of adrenocorticotropin-cortisol periodicity

Five normal male volunteers were submitted to blood sampling at 15-min intervals during seven 24-h periods staggered over 10 weeks while they underwent successively a westward and an eastward 7-h time shift by jet. Total proteins (TPP), ACTH, and cortisol concentrations were measured in each plasma sample. Possible psychological stresses were minimized by careful selection and adjustment of the volunteers before the beginning of the investigation. Physical facilities and time of the year of the execution of the study were chosen in order to avoid the influence of differences in air temperature and duration of daylight. The westward and eastward travels involved, respectively, periods of 23 and 33 h of sleep deprivation without recumbency. TPP levels were measured on each sample in order to monitor plasma dilution. Rapid fluctuations of TPP of an average magnitude of 12% were observed in all studies independently of posture or travel. They did not result from artefactual dilution due to fluid infusion. Seventy percent of the individual 24-h TPP patterns showed significantly higher TPP concentrations during ambulation than during recumbency, and a circadian rhythm with an acrophase during daytime could be detected in 21 of 34 profiles. These data thus generally support the concept of posture dependence of TPP daily variations. Transient disruptions (abolished or reversed differences between ambulation and recumbency TPP levels and/or absence or reversal of circadian rhythm) of the 24-h TPP pattern was observed in 7 of the 9 profiles obtained 1 day after the flights and was more severe after the eastward shift. It is suggested that the prolonged ambulation periods as well as the change in the type of ambulatory activity involved in commercial airline transportation caused the delay in the resumption of the usual circadian pattern of TPP levels. The time of maximal secretion (acrophase) and the quiescent period of the 24-h pattern of ACTH and cortisol adapted differently to the time shifts, suggesting that the various components of the pituitary-adrenal periodicity may be under different controls. Partial shifts of the acrophase toward the new clock time occurred as early as 1 day after travel in both directions, and the synchronization of the acrophase was complete 10 days after both westward and eastward flights. In contrast, the quiescent period needed at least 3 weeks to adapt to Chicago time (alterations consisted of desynchronization and fragmentation) but had returned to normal on the 11th day after arrival in Brussels. 'Jet lag' failed to produce quantitative secretory alterations, since no significant changes were observed in the 24-h mean levels, the amplitude of the circadian rhythms, or the frequency or global magnitude of episodic fluctuations of both hormones. Disruption in the sleep patterns, with an increase in rapid eye movement sleep, and subjective psychological discomfort, rated by Hamilton's anxiety and depression scales, were highly significant after the eastward flight only. In contrast to the persistent disruption in the pituitary-adrenal periodicity, sleep and psychological indexes had returned to normal when recorded 11 days after flight. Although no consistent correlation was found between the disturbances in the pituitary-adrenal periodicity and the level of psychological discomfort, subjects with the highest and lowest scores on the Hamilton scales showed, respectively, the slowest and fastest adaptation of the cortisol acarophase to the new clock time.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Adaptation of 24-hour hormonal patterns and sleep to jet lag.

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