Morning Onset Research Articles

Retracted: Differences in Presentation of Ischaemic and Haemorrhagic Stroke: A Systematic Review and Meta-Analysis

Abstract Background Stroke is the 2nd leading cause of death worldwide. Stroke is diagnosed by the combination of clinical symptoms and signs, and neuroimaging. Clinical features may differ between the subtypes of ischaemic and haemorrhagic stroke. We investigated whether there are differences in clinical presentation of acute ischaemic and haemorrhagic stroke. Methods We conducted a systematic review and meta-analysis according to the PRISMA statement. Inclusion criteria were (1) cohort, cross-sectional, case-control, randomised controlled trial, systematic review or meta-analysis; (2) consecutive admissions of adult individuals with an acute ischaemic or haemorrhagic stroke, confirmed by neuroimaging and (3) comparisons possible between stroke subtypes in acute stroke symptom(s). A random-effects model was used for our analyses. Results We included 58 studies (n=12,878,716; ischaemic stroke=10,814,293; haemorrhagic stroke=2,064,423). The mean age of participants was 65.54+13.84 with 44.98% women. In haemorrhagic stroke, altered GCS occurred more frequently than in ischaemic stroke (OR, 3.93 [95% CI, 2.81–5.49]; AIS/ICH=382,110/59,877, 40 studies), as did headache (OR, 3.34 [95% CI, 2.68–4.17]; AIS/ICH=22,413/6,018; 43 studies), seizure (OR, 2.42 [95% CI, 1.62–3.65]; AIS/ICH=10,427,262/2,004,681; 20 studies), vomiting (OR, 3.82 [95% CI, 2.62–5.57]; AIS/ICH=7,736/3,225; 25 studies), neck stiffness (OR, 5.21 [95% CI, 2.22–12.21]; AIS/ICH=511/168; 3 studies), syncope (OR, 2.95 [95% CI, 2.12–4.12]; AIS/ICH=2,427/494; 6 studies) and dizziness (OR, 1.33 [95% CI, 1.05–1.68]; AIS/ICH=4,730/1,213; 11 studies). Hemiplegia occurred more frequently in ischaemic stroke (OR, 0.67 [95% CI, 0.49–0.91]; AIS/ICH=15,857/4,338; 31 studies) than haemorrhagic stroke, as did ataxia (OR, 0.73 [95% CI, 0.61–0.86]; AIS/ICH=7,741/2,244; 8 studies) and morning onset (OR, 0.41 [95% CI, 0.32– 0.54]; AIS/ICH=2,721/495; 4 studies). Conclusion This review focused on synthesizing existing evidence on differences in clinical presentation between ischaemic and haemorrhagic stroke. It suggests there are substantive differences in stroke symptoms between these subtypes. These results may provide insights into future directions for clinical prediction tool development.

Abstract TP246: Circadian Variability of the Clot Burden Score in Acute Anterior Circulation Ischemic Stroke

Background/Purpose: Fibrinolytic activity in blood plasma displays a circadian rhythm with a drop in the morning hours that may predispose to acute thrombotic events. The Clot Burden Score (CBS) is a semiquantitative measure on CT angiography (CTA) of thrombus extent in proximal anterior circulation strokes that has been correlated with functional outcome. Higher clot burden has also been shown to have lower recanalization rates with intravenous thrombolytics. We aimed to investigate whether CBS is a parameter that displays circadian variability. Methods: We performed a retrospective analysis on consecutive stroke patients presenting <24 hours from symptom onset or last known well (LKW) with an occlusion in the anterior circulation confirmed on CTA. CBS was scored on a 10-point negative ordinal scale with 2-points subtracted for occlusion of the supraclinoid ICA, proximal M1, or distal M1, and 1-point subtracted for occlusion of the infraclinoid ICA, A1, or either M2 branches. No points were subtracted for occlusion distal to A1 or M2. Subjects were grouped into four 6-hour intervals, MORNING: 6:00-11:59, DAY: 12:00-17:59, EVENING: 18:00-23:59, and NIGHT: 0:00-5:59, based on the time of onset/LKW. CBS values were compared between groups using the Kruskal-Wallis test with pairwise comparisons. Results: 240 subjects were included with median age of 75 (IQR 65-84), NIHSS score of 17 (IQR 10-24), and time from onset/LKW to CTA of 5 hours (IQR 2-11). 73 subjects had onset during the MORNING, 56 during the DAY, 86 during the EVENING, and 25 during the NIGHT. The median CBS from MORNING time onset was 6 (IQR 5-9), compared to 7 (IQR 6-9) from the DAY, 7.5 (IQR 6-9) from the EVENING, and 7 (IQR 5-8.5) from the NIGHT. CBS was significantly lower in the MORNING compared to the EVENING, p=0.037. CBS was not significantly different between all other pairwise comparisons, p>0.107. Conclusion: CBS as a measure of thrombus extent in proximal anterior circulation strokes on CTA appears to show circadian variability, with lower scores (higher clot burden) during MORNING onset (6:00-11:59) than the EVENING (18:00-23:59). This may have implications for future studies of chronotherapeutic protocols.

Circadian variation in stroke onset: Differences between ischemic and hemorrhagic stroke and weekdays versus weekends

ObjectivesTo delineate diurnal variation onset distinguishing ischemic from hemorrhagic stroke, wake from sleep onset, and weekdays from weekends/holidays. Materials and MethodsWe analyzed patients enrolled in the FAST-MAG trial of field-initiated neuroprotective agent in patients with hyperacute stroke within 2h of symptoms onset. Stroke onset times were analyzed in 1h, 4h, and 12h time blocks throughout the 24h day-night cycle. Patient demographic, clinical features, stroke severity, and prehospital workflow were evaluated for association with onset times. ResultsAmong 1615 acute cerebrovascular disease patients, final diagnoses were acute cerebral ischemia in 76.5% and Intracerebral hemorrhage in 23.5%. Considering all acute cerebrovascular disease patients, frequency of wake onset times showed a bimodal pattern, with peaks on onsets at 09:00-13:59 and 17:00-18:59 and early morning (00:00-05:59) onset in only 3.8%. Circadian rhythmicity differed among stroke subtypes: in acute cerebral ischemia, a single broad plateau of elevated incidences was seen from 10:00-21:59; in Intracerebral hemorrhage, bimodal peaks occurred at 09:00 and 19:00. The ratio of Intracerebral hemorrhage to acute cerebral ischemia occurrence was highest in early morning, 02:00-06:59. Marked weekday vs weekends pattern variation was noted for acute cerebral ischemia, with a broad plateau between 09:00 and 21:59 on weekdays but a unimodal peak at 14:00-15:59 on weekends. ConclusionsWake onset of acute cerebrovascular disease showed a marked circadian variation, with distinctive patterns of a broad elevated plateau among acute cerebral ischemia patients; a bimodal peak among intracerebral hemorrhage patients; and a weekend change in acute cerebral ischemia pattern to a unimodal peak.

Acute Encephalopathy in Children From Muzaffarpur, Bihar, India, and the Potential Role of Ambient Heat Stress-Induced Mitochondrial Dysfunction.

Periodic outbreaks of acute encephalopathy in children have been reported from Muzaffarpur, Bihar, India. No infectious cause has been identified for this. This study presents the clinical and metabolic profile of children hospitalized with acute encephalopathy and the potential role of ambient heat stress. This cross-sectional study included children (<15 years) with acute encephalopathy admitted from April 4, 2019, to July 4, 2019. The clinical and laboratory investigations included infections, metabolic abnormalities, and muscle tissue analysis. The children who had metabolic derangements but no infectious cause were labeled as acute metabolic encephalopathy.The descriptive analysis summarized the clinical, laboratory, and histopathology findings, and their association with the ambient heat parameters was explored. Out of the 450 children hospitalized (median age, four years), 94 (20.9%) died.Children had early morning onset (89%), seizures (99%), fever (82%), hypoglycemia at admission (64%), raised aminotransferases (60%), and high blood urea (66%). Blood lactate (50%), lactate dehydrogenase (84%), pyruvate (100%), ammonia (32%), and creatinine phosphokinase (69%) were raised. Viral marker tests were negative. The patients had abnormal metabolic markers like decreased blood-free carnitine, elevated blood acylcarnitines, and elevated urinary lactate, oxalate, maleate, adipate, and fatty acid metabolites. Blood carnitine and acylcarnitine levels normalized in 75% of the patients treated with carnitine and coenzyme-Q.Muscle tissues showed megamitochondria on electron microscopy and reduced respiratory enzyme complex-I activity. A significant correlation between the number of admissions and ambient heat indices was observed. The findings suggest secondary mitochondrial dysfunction as a possible mechanism for acute encephalopathy in children from Muzaffarpur, Bihar, and ambient heat stress as a possible risk factor.

Nomogram predicting testicular torsion in Japanese patients with acute scrotal pain using physical examination findings and environmental conditions: Development and prospective external validation.

To develop a prediction tool based on physical findings and environmental conditions without utilizing color Doppler ultrasonography to guide non-urologists and patients' families in determining the testicular torsion possibility among patients with acute scrotal pain. Overall, 110 consecutive patients aged ≤30 years with acute scrotal pain at Saitama Medical Center between 2012 and 2014 were retrospectively evaluated. Physical examination results, including scrotal inspection, palpation and gait observation, and environmental conditions at pain onset (time range and ambient temperature) were collected. Multivariate analysis identified significant and independent risk factors for testicular torsion, and a nomogram predicting testicular torsion was constructed. The model underwent prospective validation in an independent set of 123 consecutive patients admitted with acute scrotal pain to our institution between 2015 and 2017. Testicular torsion diagnosis rates were 27% (30/110) and 26% (32/123) in the training and validation cohorts, respectively. Logistic regression analysis showed four risk factors for developing testicular torsion: abnormal testicular position, walking difficulty, midnight to early morning onset and ambient temperature <15°C at pain onset. The constructed nomogram showed that the areas under the receiver operating characteristic curves were 0.92 and 0.84 for the training and validation cohorts, respectively. The calibration plot showed an acceptable fitness between the predicted probability and the observed rate of testicular torsion. A novel nomogram was developed solely based on physical findings and environmental conditions to predict testicular torsion in Japanese patients with acute scrotal pain.

Aerosols in the convective boundary layer: Shortwave radiation effects on the coupled land‐atmosphere system

AbstractBy combining observations and numerical simulations, we investigated the responses of the surface energy budget and the convective boundary layer (CBL) dynamics to the presence of aerosols. A detailed data set containing (thermo)dynamic observations at CESAR (Cabauw Experimental Site for Atmospheric Research) and aerosol information from the European Integrated Project on Aerosol, Cloud, Climate, and Air Quality Interactions was employed to design numerical experiments reproducing two typical clear‐sky days, each characterized by contrasting thermodynamic initial profiles: (i) residual layer above a strong surface inversion and (ii) well‐mixed CBL connected to the free troposphere by a capping inversion, without the residual layer in between. A large‐eddy simulation (LES) model and a mixed‐layer (MXL) model, coupled to a broadband radiative transfer code and a land surface model, were used to study the impacts of aerosols on shortwave radiation. Both the LES model and the MXL model results reproduced satisfactorily the observations for both days. A sensitivity analysis on a wide range of aerosol properties was conducted. Our results showed that higher loads of aerosols decreased irradiance imposing an energy restriction at the surface, delaying the morning onset of the CBL and advancing its afternoon collapse. Moderately to strongly absorbing aerosols increased the heating rate contributing positively to increase the afternoon CBL height and potential temperature and to decrease Bowen ratio. In contrast, scattering aerosols were associated with smaller heating rates and cooler and shallower CBLs. Our findings advocate the need for accounting for the aerosol influence in analyzing surface and CBL dynamics.

Circadian Variation in Ictus of Aneurysmal Subarachnoid Hemorrhage

Temporal patterns in aneurysmal subarachnoid hemorrhage (aSAH) may provide insight into modulation, and therefore, prevention of hemorrhage. We investigated the time of hemorrhage and its relationship to traditional risk factors among patients admitted with aSAH. Admitted patients with aSAH were prospectively followed through outcomes and baseline demographics were abstracted through chart review. The group temporal distribution by hour of onset was summarized with cosinor nonlinear least squares. aSAH onset was gathered into night (2300-0500), morning (0500-1100), afternoon (1100-1700), and evening (0500-2300) daily phases. The odds ratio (OR) with 95% CI was calculated for having an aSAH during the morning, afternoon, and evening hours using night as a reference. Multinomial logit models were fitted using aSAH cases across time blocks to determine their associations with different risk factors. 202 patients had the hour of hemorrhage available, and 49 had phase identifiable [total 251: 38 (15%) night, 98 (39%) morning, 58 (23%) afternoon, 57 (23%) evening]. The peak hours of aSAH were between 0700 and 0800 representing 13% of the sample, with a significant cosinor-fitted phase of 7.33(95% CI 5.30, 9.36). For all aSAH cases, morning onset was significantly more common than night onset (OR = 2.58, 95% CI = 1.77-3.75). Nonsmokers were more likely to have aSAH in the morning than smokers (P = 0.043, OR = 3.10, 95% CI = 1.33-7.23). aSAH occur in a diurnal, morning prevalent pattern regardless of traditional aSAH risk factors. The association of these risk factors with existing onset patterns should be investigated in future studies.

Is there any circadian variation consequence on acute case fatality of stroke? Takashima Stroke Registry, Japan (1990-2003)

Circadian periodicity in the onset of stroke has been reported. However, it is unclear whether this variation affects the acute stroke case fatality. Time of the day variation in stroke case fatality was examined using population-based stroke registration data. Stroke event data were acquired from the Takashima Stroke Registry, which covers a stable population of approximately 55,000 in Takashima County in central Japan. During the period of 1990-2003, there were 1080 (549 men and 531 women) cases with classifiable stroke onset time. Stroke incidence was categorized as occurring at night (midnight-6 a.m.), morning (6 a.m.-noon), afternoon (noon-6 p.m.), and evening (6 p.m.-midnight). The 28-day case fatality rates and 95% confidence intervals (95% CI) were calculated by gender, age, and stroke subtype across the time blocks. After adjusting for gender, age at onset, and stroke severity at onset, the hazard ratios for fatal strokes in evening, night, and morning were calculated, with afternoon serving as the reference. For all strokes, the 28-day case fatality rate was 23.3% (95% CI:19.4-27.6) for morning onset, 16.9% (95% CI:13.1-21.6) for afternoon onset, 18.3% (95% CI:13.6-24.1) for evening onset, and 21.0% (95% CI:15.0-28.5) for the night onset stroke. The case fatality for strokes during the morning was higher than the case fatality for strokes during afternoon. This fatality risk excess for morning strokes persisted even after adjusting for age, gender, and stroke severity on onset in multivariate analysis. In the examination of circadian variation of stroke case fatality, 28-day case fatality rate tended to be higher for the morning strokes.

PROXISOME PROLIFERATOR-ACTIVATED RECEPTOR-α MEDIATES HIGH-FAT, DIET-ENHANCED DAILY OSCILLATION OF PLASMINOGEN ACTIVATOR INHIBITOR-1 ACTIVITY IN MICE

Acute thrombotic events frequently occur in the early morning among hyperlipidemic patients. The activity of plasminogen activator inhibitor-1 (PAI-1), a potent inhibitor of the fibrinolytic system, oscillates daily, and this is considered one mechanism that underlies the morning onset of acute thrombotic events in hyperlipidemia. Although several studies have reported the expression of the PAI-1 gene is under the control of the circadian clock system, the molecular mechanism of the circadian transactivation of PAI-1 gene under hyperlipidemic conditions remains to be elucidated. Here, the authors investigated whether hyperlipidemia induced by a high-fat diet (HFD) enhances the daily oscillation of plasma PAI-1 activity in mice. The mRNA levels of the PAI-1 gene were increased and rhythmically fluctuated with high-oscillation amplitude in the livers of wild-type mice fed with the HFD. Circadian expression of proxisome proliferator-activated receptor-α (PPARα) mRNA was also augmented as well as that of PAI-1. Chromatin immunoprecipitaion showed the HFD-induced hyperlipidemia significantly increased the binding of PPARα to the PAI-1 promoter. Luciferase reporter analysis using primary hepatocytes revealed CLOCK/BMAL1-mediated PAI-1 promoter activity was synergistically enhanced by cotransfection with PPARα/retinoid X receptor-α (RXRα), and this synergistic transactivation was repressed by negative limbs of the circadian clock, PERIOD2 and CRYPTOCHROME1. As expected, HFD-induced PAI-1 mRNA expression was significantly attenuated in PPARα-null mice. These results suggest a molecular link between the circadian clock and lipid metabolism system in the regulation of PAI-1 gene expression, and provide an aid for understanding why hyperlipidemia increases the risk of acute thrombotic events in the morning. (Author correspondence: ssoeda@fukuoka-u.ac.jp)

The related causes in very early morning onset of stroke

We investigated the influence of early awakening and related factors on onset of cerebrovascular disease (CVD). Totally 1199 stroke patients, in whom the onset time was known, at 3 reference hospitals were included in this study. The effects of demographic, medical, and pathophysiological factors on the circadian pattern of an unselected series of patients with ischemic stroke were analyzed. Nine-hundred seventeen CVD patients with cerebral infarction (CI), 240 patients with intracerebral hemorrhage (CH), and 42 patients with subarachnoid hemorrhage (SAH) were identified. The greatest portion of strokes (32.5%) occurred between 03:00 and 06:00 a.m. Nearly one half of the strokes in this series occurred in the very early- to mid-morning hours. This analysis of strokes provides strong evidence with a higher risk in the early morning hours (03:00 a.m. to 06:00 a.m.), and lower risk during the night time period (21:00 p.m. to midnight). Approximately 1 of every 3 strokes (1 of 3 ischemic strokes, 1 of 6 hemorrhagic strokes, and 1 of 8 subarachnoid hemorrhages) is attributable to the early morning excess. This difference tried to be explained by three ways: cold weather, religious factors, and physiological mechanisms.

A Dose-Ranging Study of a Methylphenidate Transdermal System in Children With ADHD

This was a multicenter, double-blind, randomized, dose-ranging study of a methylphenidate (MPH) transdermal system (MTS). Medication (placebo, 0.45, 0.9, and 1.8 mg/h) was crossed with application time (6 a.m., 7 a.m.) to evaluate MTS efficacy and influence of exposure time on morning effects. The study took place in a summer treatment program (STP) at three sites, with 36 children aged 7-12 years with attention-deficit/hyperactivity disorder. Each treatment was administered for 1 day in random order, for a total of 8 days. Behavioral and academic measures were taken as well as patch wear characteristics and side effects. Evaluable participant data were analyzed in a series of dose x application time multivariate analyses of variance. All MTS conditions were significantly different from placebo across measures. Time of application had no significant effect on daily behavior, and effects of application time on morning behavior were inconclusive. Consistent with previous results in this setting, the highest dose produced limited incremental benefit compared with the mid-range dose. The wear characteristics of the MTS were acceptable, and the formulation was well tolerated. The MTS produced significant effects that were similar to those previously reported with comparable MPH doses. There does not appear to be a substantial effect of application time on total daily functioning in this setting; further controlled time-course studies will be necessary to evaluate the question of morning onset fully.

Besteht ein Zusammenhang zwischen dem Schlafapnoesyndrom und der zirkadianen Häufung von Myokardinfarkten in den Morgenstunden?

To determine whether there is a relationship between the circadian rhythm of acute myocardial infarction (AMI) in the morning hours and the sleep apnea syndrome (SAS). 203 patients who had sustained an AMI were examined 7-14 days later for sleep-associated breathing disorders using a 5-channel recording system. The diagnostic criterion for SAS was > 10 episodes of apnea and hypopnea per hour (AHI >10). 76 % of all patients were male, mean age 62 years. SAS was diagnosed in 91 of the 203 patients (44.8 %). Compared to the 112 patients without SAS there were significantly more AMI in the morning hours (6:00 am to 12:00 am) in the SAS-group (49.5 %) than in the non-SAS-group (21.4 %). The two groups differed with regard to the symptoms of day-time sleepiness (29.7 % vs 17.0 %), age (mean 64.6 years vs 60.2 years), gender (83.5 % vs 69.9 % male) and smoking (33.0 % vs 51.8 %). There were no significant differences in Body mass index, hypertension, hyperlipoproteinemia, diabetes mellitus, family history, history of cardiovascular disease and taking of sedatives. The strong association between SAS and morning onset of AMI found in this study could be the result of a sympathetic stress reaction to the breathing disorder.

Molecular mechanisms of morning onset of myocardial infarction.

We recently isolated a novel bHLH/PAS protein, CLIF (cycle like factor), by yeast two-hybrid screening of human umbilical endothelial cell cDNA library. CLIF is preferentially expressed in endothelial and neuronal cells. Because CLIF is expressed in vascular endothelial cells and forms a heterodimer with CLOCK, the key transcription factor controlling the circadian rhythm, we hypothesized that CLIF regulates the circadian oscillation of PAI-1 gene expression in endothelial cells. Northern blot analysis of mouse organs showed circadian oscillations of PAI-I mRNA levels. In addition, the clock-related genes also showed circadian oscillation in peripheral tissues. In endothelial cells, the heterodimer of CLIF and CLOCK upregulated the PAI-1 gene expression through E-box sites. Furthermore, Period and Cryptochrome, which are negative regulators in the feedback loop of the biological clock, inhibited PAI-1 promoter activation by the CLOCK:CLIF heterodimer. These results suggest that the peripheral tissues have their own biological clock and CLIF regulates the circadian oscillation of PAI-1 gene expression in endothelial cells. This study suggests a novel molecular mechanism of the morning onset of myocardial infarction. Here we review our recent work and literature.

CLIF, a Novel Cycle-like Factor, Regulates the Circadian Oscillation of Plasminogen Activator Inhibitor-1 Gene Expression

The onset of myocardial infarction occurs frequently in the early morning, and it may partly result from circadian variation of fibrinolytic activity. Plasminogen activator inhibitor-1 activity shows a circadian oscillation and may account for the morning onset of myocardial infarction. However, the molecular mechanisms regulating this circadian oscillation remain unknown. Recent evidence indicates that basic helix-loop-helix (bHLH)/PAS domain transcription factors play a crucial role in controlling the biological clock that controls circadian rhythm. We isolated a novel bHLH/PAS protein, cycle-like factor (CLIF) from human umbilical vein endothelial cells. CLIF shares high homology with Drosophila CYCLE, one of the essential transcriptional regulators of circadian rhythm. CLIF is expressed in endothelial cells and neurons in the brain, including the suprachiasmatic nucleus, the center of the circadian clock. In endothelial cells, CLIF forms a heterodimer with CLOCK and up-regulates the PAI-1 gene through E-box sites. Furthermore, Period2 and Cryptochrome1, whose expression show a circadian oscillation in peripheral tissues, inhibit the PAI-1 promoter activation by the CLOCK:CLIF heterodimer. These results suggest that CLIF regulates the circadian oscillation of PAI-1 gene expression in endothelial cells. In addition, the results potentially provide a molecular basis for the morning onset of myocardial infarction.

Effect of Enclosure Quality on Reactivity and Welfare of Captive Soemmerring's Gazelle (Gazella soemmerringii)

The welfare of nonhuman animals in zoos is a great challenge to the zookeeper. Changes in the behavioral response of captive animals to their immediate environment can be used as a method for evaluating their welfare status. This study evaluates reactive responses of 3 groups of captive Soemmerring's gazelle (Gazella soemmerringii) kept in enclosures of different quality at Giza Zoo, Egypt. The study ascribes variations in observed behaviors to the differences in the living standards of the 3 groups. The group most concealed from visitors' disturbance (Group 3) was the least reactive. With the morning onset of human-nonhuman animal interaction, reactivity reached significantly higher levels. The study noted no difference in reactivity between male and female animals. The main sign of the animals' alertness was their attention to sources of disturbances; vocalization was minimal. Animals in Groups 1 and 2, those most accessible to visitors, had higher agonistic reactions than animals in Group 3.

DAILY ACTIVITY PATTERNS OF HORSE FLIES (DIPTERA: TABANIDAE: HYBOMITRA SPP.) IN NORTHERN AND SOUTHERN MANITOBA

AbstractDaily patterns of host-seeking activity by female tabanids were determined by hourly trapping (0530–2230 hours) with Manitoba horse fly traps at Seven Sisters, Man., 4 days a week, throughout the summer of 1988. Hybomitra epistates (Osten Sacken) and H. pechumani Teskey and Thomas were most active during late morning or mid-day; H. arpadi (Szilady) and H. zonalis (Kirby) in early afternoon; H. affinis (Kirby), H. illota (O.S.), and H. lasiophthalma (Macquart) in late afternoon; H. nitidifrons nuda (McDunnough) and H. lurida (Fallen) in early evening.The morning onset of tabanid flight activity usually was related to temperature, but the cessation of activity in the evening was related either to temperature or light, depending on which was first to fall below threshold levels. Tabanid flight activity was generally low at temperatures below 20°C, although H. lasiophthalma and H. affinis occasionally were caught at 12°C. Little flight activity occurred at light intensity levels below 1000 lx regardless of temperature. At Churchill, Man., where tabanids were trapped hourly from 27 July to 15 August in 1988, H. affinis and H. frontalis (Walker) activity was low below 14°C, although some activity occurred at 6°C.

Control of structural rhythms in the lateral eye of Limulus: interactions of natural lighting and circadian efferent activity

The structure of the Limulus polyphemus retina changes with the time of day. The structural changes exhibit a circadian rhythm when the animal is kept in constant darkness. During subjective night, the aperture of each visual unit (ommatidium) widens and flattens, allowing more photons to impinge on the underlying photoreceptors. In addition, the photosensitive region (rhabdom) of the photoreceptors widens and shortens. During subjective day, these changes reverse: both the aperture and rhabdom elongate and narrow, reducing the number of photons caught by the photoreceptors. The endogenous structural rhythm is mediated by efferent optic nerve activity generated from a circadian clock located in the brain. Eliminating the efferent input by cutting the optic nerve blocks the rhythm and shocking the cut nerve restores it. Natural lighting magnifies the structural rhythm. Daylight induces photomechanical movements, enhancing the endogenous daytime changes that decrease photon catch. The onset of darkness enhances endogenous nighttime changes that increase photon catch. Cutting the optic nerve blocks all structural changes, both endogenous and photomechanical. In the animal's natural environment, the effects of circadian efferent input and natural lighting are thus reciprocal: The evening onset of efferent activity pushes retinal structure in one direction; the morning onset of daylight pulls it in the other. The 2 processes, however, are not equivalent. In the absence of cyclic lighting, circadian efferent input produces an attenuated structural rhythm, but cyclic lighting alone produces no rhythm.

Entrainment of the circadian rhythm in the rat pineal N-acetyltransferase activity by prolonged periods of light.

Entertainment of the circadian rhythm in the pineal N-acetyltranferase activity by prolonged periods of light was studied in rats synchronized with a light:dark regime of 12:12 h by observing phase-shifts in rhythm after delays in switching off the light in the evening or after bringing forward of the morning onset of light. When rats were subjected to delays in switching off the light of up to 10 h and then were released into darkness, phase-delays of the evening N-acetyltransferase rise during the same night corresponded roughly to delays in the light switch off. However, phase-delays of the morning decline were much smaller. After a delay in the evening switch off of 11 h, no N-acetyltransferase rhythm was found in the subsequent darkness. The evening N-acetyltransferase rise was phase-delayed by 6.2 h at most 1 day after delays. Phase-delays of the morning N-acetyltransferase decline were shorter than phase-delays of the N-acetyltransferase rise by only 0.7 h to 0.9 h at most. Hence, 1 day after delays in the evening switch off, the period of the high night N-acetyltransferase activity may be shortened only slightly. The N-acetyltransferase rhythm was abolished only after a 12 h delay in switching off the light. Rats were subjected to a bringing forward of the morning light onset and then were released into darkness 4 h before the usual switch off of light. In the following night, the morning N-acetyltransferase decline, but not the evening rise, was phase advanced considerably. Moreover, when the onset of light was brought forward to before midnight, the N-acetyltransferase rise was even phase-delayed. Hence, 1 day after bringing forward the morning onset of light, the period of the high night N-acetyltransferase activity may be drastically reduced. When rats were subjected to a 4 h light pulse around midnight and then released into darkness, the N-acetyltransferase rhythm in the next night was abolished. The data are discussed in terms of a two-component pacemaker controlling the N-acetyltransferase rhythm. It is suggested that delays in the evening switch off of light may disturb the N-acetyltransferase rhythm the next day only a little, as the morning component may adjust to phase-delays of the evening component almost within one cycle.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of Sleep Duration on Classic Migraine and Depression Headache Pain: Case Reports

AbstractHeadache etiology research has not supported the traditional headache classification system. This paper provides evidence that classic migraine headache and muscle contraction headaches that appear in the morning (depression headaches) may share a common etiology and respond to the same treatment—reducing sleep duration. Three clinical cases with long-standing headaches are presented, one a depression headache patient and two classic migraineurs. All case histories showed a strong relationship between extended sleep duration and headaches, and headaches completely remitted after patients consistently awakened one-half to one hour earlier than their normal rising time. Eight common migraineurs showed no such relationship and failed to respond to sleep manipulations.We conclude that classic migraine and morning onset “muscle contraction” (or depression) headaches may result from serotonergic mechanisms which are triggered by excessive sleep. Common migraines, in contrast, may be related to oral habi...

Subjective distress accompanying headache attacks: Evidence for a cognitive shift

This study examined the nature of the cognitions experienced by chronic headache sufferers during headache episodes and assessed whether these cognitions were differentially related to illness behavior and to symptom properties of headache attacks. The data were examined both in terms of headache severity and in terms of the muscle contraction-migraine dichotomy. Forty-four headache patients monitored, with an open-ended assessment format, the thoughts and feelings experienced prior to and during episodes of head pain. The majority of patient responses could reliably be placed into 1 of 2 categories: (a) stress-related cognitions and (b) disorder-related cognitions. The percentage of headache-related thoughts and feelings correlated significantly with several indices of headache severity, including intensity of pain, quality of pain, length of headache attacks, and presence of early morning onset. Further significance to these findings was added by demonstrating that the patients who predominantly reported disorder-related cognitions also displayed a tendency to deny life problems not related to pain. The data were taken as support for the hypothesis that chronic headache disorders of increased severity are accompanied by a cognitive shift whereby the patient's primary concern moves from situational and interpersonal stress to distress associated with the disorder itself.