A graphical and statistical method for investigation of time series in chronobiology according to the cosinor procedure

Light cues drive community-wide transcriptional shifts in the hypersaline South Bay Salt Works

The transition from day to night brings sweeping change to both environments and the organisms within them. Diel shifts in gene expression have been documented across all domains of life but remain understudied in microbial communities, particularly those in extreme environments where small changes may have rippling effects on resource availability. In hypersaline environments, many prominent taxa are photoheterotrophs that rely on organic carbon for growth but can also generate significant ATP via light-powered rhodopsins. Previous research demonstrated a significant response to light intensity shifts in the model halophile Halobacterium salinarum, but these cycles have rarely been explored in situ. Here, we examined genome-resolved differential expression in a hypersaline saltern (water activity (aw) ≅ 0.83, total dissolved solids = 250.7 g L-1) throughout a 24-h period. We found increased transcription of genes related to phototrophy and anabolic metabolic processes during the day, while genes related to aerobic respiration and oxidative stress were upregulated at night. Substantiating these results with a chemostat culture of the environmentally abundant halophilic bacterium Salinibacter ruber revealed similar transcriptional upregulation of genes associated with aerobic respiration under dark conditions. These results describe the potential for light-driven changes in oxygen use across both a natural hypersaline environment and a pure culture.

Fractures in Children Due to Firearm Activity

The purpose of this study was to investigate fracture patterns due to pediatric firearm injuries. The data used was from the US Firearm Injury Surveillance Study 1993–2019. Over these 27 years, there were 19,033 children with fractures due to firearm activity with an average age of 12.2 years; 85.2% were boys and the firearm was a powder type in 64.7%. The finger was the most common fracture location, while the tibia/fibula was the most common location for those admitted to the hospital. Children ≤ 5 years of age sustained more skull/face fractures; most spine fractures occurred in the 11–15-year age group. The injury was self-inflicted in 65.2% of the non-powder and 30.6% of the powder group. The injury intent was an assault in 50.0% of the powder and 3.7% of the non-powder firearm group. Powder firearms accounted for the majority of the fractures in the ≤5 and 11–15 year-olds, non-powder firearms accounted for the majority of the fractures in the 6–10 year-olds. Injuries occurring at home decreased with increasing age; there was an increase in hospital admissions over time. In conclusion, our findings support the need for safe storage of firearms in the home away from children. This data will be helpful to assess any changes in prevalence or demographics with future firearm legislation or other prevention programs. The increasing acuity of firearm-associated injuries seen in this study is detrimental to the child, impacts familial wellbeing, and results in significant financial costs to society.

Assault related injury visits in US emergency departments: An analysis by weekday, month and weekday-by-month

This study investigated the temporal variation (month and day) in assault-related injuries presenting to the US Emergency Departments (ED). An IRB exempt, retrospective review of prospectively collected data was performed using the National Electronic Injury Surveillance System Database from 2005 to 2017 for six categories of assault-related injuries-altercation, sexual assault, robbery, intimate partner violence (IPV), other specified assaults and unknown assault types. National estimates of injuries and associated variables were obtained using SUDAAN software, followed by cosinor analyses for the variation of month and weekday of injury. Three-dimensional topographic representations for weekday-by-month analyses were also created. Over this 13-year time span, there were more than 21 million injury visits due to assault, accounting for 6.57% of all ED visits. While there was no change in the incidence of total number of assaults over the study period, there was a significant increase in the annual percentage incidence of IPV (1.17%; p = .0094) and robbery (2.56%; p = .0001). Cosinor analyses demonstrated a mid-summer peak for all assault types except for robberies (late summer). All assault types showed a weekend peak (late Saturday or early Sunday). Topographical contours exhibited a peak in July and August on early Sunday for all assaults, however the month varied by the type of assault, with weekend peaks in the spring and winter for IPV. This information can be used in prospective resource planning for management and prevention strategies.

Seasonal differences in emergency department visits for scooter associated injuries

Hoverboards and electric scooters have surged in popularity in the past decade. These devices carry their own injury profiles and have caused increasing emergency department visits for injury. The purpose of this study was to compare both hoverboards and electric scooters to more traditional scooters and evaluate seasonal variations in their injury patterns. The National Electronic Injury Surveillance System (NEISS) database was used, downloading cases with the appropriate consumer product codes. Four distinct scooter groups were created, and were: non-powered scooters, powered scooters, electric scooters, and hoverboards. Statistical analyses were first performed with SUDAAN software to account for the stratified and weighted nature of the data to obtain national estimates of injuries and associated demographic variables. Cosinor analyses were performed to analyze the estimated number of emergency department (ED) visits for rhythmic variation by month and weekday of injury. Weekday by month analyses were studied using a three-dimensional topographic concept. Overall, there were over 1 million ED visits over the 20 years for injuries due to the four different types of scooters (75.8% nonmotorized scooters, 12.4% motorized scooters, 6.8% hoverboards, and 2.4% electric scooters). Cosinor analyses demonstrated that there was a peak in injuries in the summer and on weekends for all scooters, except for hoverboards. For hoverboards 21% of all ED visits occurred in December, with mostly occurring exactly around Christmas Day. This study confirms previous findings that scooter injuries occur mostly in warmer months and is the first to demonstrate a topographical "Christmas Effect" of hoverboard injuries. This information can be used in health care resource allocation as well as design of potential prevention strategies.

Seasonal variation in adult hip disease secondary to osteoarthritis and developmental dysplasia of the hip

AIM

To determine if there was a seasonal variation in adults undergoing total hip arthroplasty for end stage hip disease due to osteoarthritis (OA) or sequelae of developmental dysplasia of the hip (DDH).

METHODS

The total hip registry from the author’s institution for the years 1969 to 2013 was reviewed. The month of birth, age, gender, and ethnicity was recorded. Differences between number of births observed and expected in the winter months (October through February) and non-winter mo (March through September) were analyzed with the χ² test. Detailed temporal variation was mathematically assessed using cosinor analysis.

RESULTS

There were 7792 OA patients and 60 DDH patients who underwent total hip arthroplasty. There were more births than expected in the winter months for both the DDH (P < 0.0001) and OA (P = 0.0052) groups. Cosinor analyses demonstrated a peak date of birth on 1^st October.

CONCLUSION

These data demonstrate an increased prevalence of DDH and OA in those patients born in winter.

Seasonal variation in children with developmental dysplasia of the hip

BACKGROUND

It has been postulated that developmental dysplasia of the hip (DDH) is more frequent in infants born in the winter months. It was the purpose of this study to ascertain if there was any seasonal variation in DDH at the author's institution and compare/contrast our results with those in the literature using rigorous mathematical fitting.

METHODS

All children with DDH treated at the author's institution from 1993 to 2012 were identified. The month of birth was recorded and temporal variation was analyzed using cosinor analysis. Similar data from the literature was analyzed.

RESULTS

There were 424 children (363 girls, 61 boys). An additional 22,936 children were added from the literature for a total of 23,360. Pearson's Chi-square test demonstrated a non-uniform distribution in the month of birth for both our 424 children as well as the combined literature series in both the Northern and Southern hemispheres. Cosinor analysis of the 424 children demonstrated double peaks in mid-March and mid-October. For the entire 23,360 children, no seasonal variation was observed in 2,205 (9.4 %), a single winter peak in 16,425 (70.3 %), a single summer peak in 1,280 (5.5 %), and double peaks in the spring and autumn in 3,450 (14.8 %).

CONCLUSIONS

This study partly supports the hypothesis of tight clothing/cold temperature as one factor in the etiology of DDH with the tighter clothing/swaddling increasing the risk of DDH. However ~20 % of the DDH births demonstrated a non-winter peak. The single summer and double spring/autumn peaks, as well as in those series where no seasonal variation was noted, refutes the cold winter clothing hypothesis. Perhaps these different patterns in seasonal variation represent the heterogeneity of the genetic factors in DDH interacting with external factors (temperature and clothing) and internal factors (metabolic). Further study will be required to understand these different patterns in DDH seasonal variation.

LEVEL OF EVIDENCE

IV-case series.

Temporal variation in United States firearm injuries 1993-2008: results from a national data base

BACKGROUND

There are few studies that address temporal variation in firearm associated injuries. It was the purpose of this study to analyze the temporal variation in the types and patterns of injuries associated with firearm use from a national data base.

METHODS

The database used was the Inter-University Consortium for Political and Social Research Firearm Injury Surveillance Study 1993-2008. Emergency department visits associated with firearm use were analyzed for month and day of the week for various demographic variables. Statistical analyses were performed using SUDAAN 10™ software to give national estimates. Temporal variation by month or day was assessed using histograms, circular distributions, and cosinor analyses. Variation by month and day combined were analyzed using three dimensional contours.

RESULTS

There were an estimated 1,841,269 injuries. Circular analyses demonstrated a non-uniform distribution for all parameters for both month and day of injury (p less than 0.001). The overall peak was September 15 with several exceptions. Injuries from BB guns had a peak on May 22, a diagnosis of a foreign body on July 11, and patients aged 10 to 14 years on April 9.The peak day was always Saturday/Sunday when significant variation existed. There were many different patterns for month and day combined. Some were "a rapidly rising high mountain starting at sea level" (hunting), or others a "series of mountain ranges starting from a high plain or steppe" (hospital admissions).

CONCLUSIONS

This study provides altogether new information regarding temporal variation for injuries associated with firearms in the USA. These results can be used to assist medical resource allocation and prevention campaigns. Education campaigns can be emphasized before the peaks for which prevention is desired (eg. BB gun prevention campaigns should be concentrated in March, prior to the April/May peak).

Temporal variation in childhood injury from common recreational activities

BACKGROUND/PURPOSE

To investigate the month and day of the week of injury in common childhood activities using the National Electronic Injury Surveillance System database.

METHODS

All emergency department visits 2002–2006 from bicycles/tricycles, scooters, playground equipment, swimming/water activities, skiing/snowboarding, trampolines, and skating were analysed. The NEISS weighted and stratified data set was analysed using SUDAAN software. Weekday and month of injury, gender, race, anatomical location of the injury, geographical location of injury, and disposition were tabulated. Simple variation by month or weekday was analysed using cosinor analysis; combined variation for both month and weekday was analysed by topographical analysis.

RESULTS

There were an estimated 4.61 million emergency department visits for injuries from these activities in children in the United States. The average age was 9.5 years; there were 1.65 million girls (35.9%) and 2.97 boys (64.1%). Cosinor analysis demonstrated significant single peaks for month of injury for snow activities (January 27), trampolines (June 10), scooters (June 24), cycling (July 6), and water (July 12) activities. Double cosinor peaks were noted for skating (April 13 and September 12) and playground (April 22 and September 21) activities. Cosinor analyses demonstrated that the peak week days of injury were Monday for trampoline and snow activities, Saturday/Sunday for skating activities, Sunday for cycling, and Wednesday for playground equipment. There was no peak injury day for scooter or water activities. Topographical representation of paediatric injuries demonstrated that injuries from slides most frequently occurred April–May on Wednesdays and Saturdays, and those on swings April–May all days except Tuesday. Monkeybar injuries were bimodal, with the spring peak on Wednesday–Thursday in April/May and the fall peak Tuesday–Friday in September. Rollerblade injuries occurred Saturday–Sunday from March/April; rollerskates on Saturday–Sunday in January–April, and skateboards Saturday–Monday in August–October and Sundays in April.

CONCLUSIONS

These findings can be used to further guide childhood injury prevention programmes/campaigns and especially track improvements after targeted prevention programmes. Public parks and schools should check/correct the status of playground landing surfaces just before the bimodal peaks. Education campaigns reinforcing the need for bicycle helmets could be concentrated immediately before the increase in cycling activity – March on weekends and April/May for weekdays.

Increased REM Sleep Associated with Melatonin Deficiency after Pinealectomy: A Case Study

The objectives of the investigation were to assess hypersomnia, which progressively appeared in a young patient after a pinealectomy, chemotherapy, and radiotherapy for a typical germinoma, as well as the potential benefit of melatonin administration in the absence of its endogenous secretion. 24 h ambulatory polysomnography and the Multiple Sleep Latency Test (MSLT) were performed; in addition, daily plasma melatonin, cortisol, growth hormone, prolactin, and rectal temperature profiles were determined before and during melatonin treatment (one 2 mg capsule given nightly at 21:00 h for 4 weeks). MSLT showed abnormal sleep latency and two REM sleep onsets. Nighttime total sleep duration was lengthened, mainly as a consequence of an increased REM sleep duration. These parameters were slightly modified by melatonin replacement. Plasma melatonin levels, which were constantly nil in the basal condition, were increased to supraphysiological values with melatonin treatment. The plasma cortisol profile showed nycthemeral variation within the normal range, and the growth hormone profile showed supplementary diurnal peaks. Melatonin treatment did not modify the secretion of either hormone. The plasma prolactin profile did not display a physiological nocturnal increase in the basal condition; however, it did during melatonin treatment, with the rise coinciding with the nocturnal peak of melatonin concentration. A 24 h temperature rhythm of normal amplitude was persistent, though the mean level was decreased and the rhythm was dampened during melatonin treatment. The role of radiotherapy on the studied parameters cannot be excluded; the findings of this case study suggest that the observed hypersomnia is not the result of melatonin deficiency alone. Overall, melatonin treatment was well tolerated, but the benefit on the sleep abnormality, especially on daytime REM sleep, was minor, requiring the re-introduction of modafinil treatment.

Epidemiology and mechanisms of femur fractures in children

The most common pediatric orthopaedic injury requiring hospitalization is a femur fracture. This study aimed to identify the epidemiology and mechanisms of injury so that these injuries might be reduced through specifically targeted safety measures. Data for this study were culled from the 2000 Kids' Inpatient Database representing over 2.5 million pediatric hospital discharges. Of the nearly 10,000 femur fractures, 1076 (11%) occurred in children younger than 2 years; 2119 (21%) in children aged 2 to 5 years; 3237 (33%) in children aged 6 to 12 years; and 3528 (35%) in adolescents aged 13 to 18 years. The most (71%) occurred in male patients. Falls and motor vehicle collisions accounted for two thirds of those injuries, with the incidence of falls greater in the younger children and motor vehicle collisions more prevalent in older children. Fifteen percent of femoral fractures in children younger than 2 years were because of child abuse. Length of hospital stay, number of diagnoses and procedures, and hospital charges were greatest in the adolescent age group, likely because of high-energy trauma with resultant polytrauma. Hospital charges were more than 222 million dollars with the average charge over 2.5 times that in adolescents compared with infants/toddlers. Pediatric orthopaedists must continue to press for increased safety for our children, particularly adolescent motor vehicle safety. Abuse should be considered when a child younger than 2 years presents with a femoral fracture.

Hypoprolactinemic rats under conditions of constant darkness or constant light. Effects on the sleep-wake cycle, cerebral temperature and sulfatoxymelatonin levels

In genetic hypoprolactinemic rats under light-dark (LD) conditions, the circadian rhythms of slow-wave (SWS) and paradoxical (PS) sleep display an alteration of their phase relationship. The aim of our study was to investigate the effects of constant darkness (DD) or constant light (LL) on the daily distribution and amounts of sleep-wake stages, cerebral temperature and concentrations of the urinary melatonin metabolite, 6-sulfatoxymelatonin, in prolactin-deficient rats. After 3 weeks of DD, the SWS period was 24 h 8+/-6 min and the acrophase occurred at 15:44+/-1:35, while for PS, the period was more stable than during LD (24 h 10+/-8 min vs. 24 h 55+/-43 min) and the acrophase occurred at 16:44+/-1:54. Under LL conditions, circadian sleep rhythms persisted during the first 3 days, then completely disappeared during the third week, to be replaced by ultradian rhythms (period of 4-6 h). Time-series analysis showed that the two sleep states became synchronous as early as the second day under constant conditions. The total amount of PS was increased under both conditions (LL and DD) at the expense of duration of waking. Under LD and constant conditions, the pattern of changes in cerebral temperature was similar to that for wakefulness (W). Sulfatoxymelatonin was rhythmically secreted under both LD and DD conditions, whereas, under LL conditions, its rhythm was abolished. The results show that, in IPL rats in the absence of a zeitgeber, the PS and SWS rhythms recover a synchronous phase relationship and PS amounts are increased.

Perinatal development of circadian melatonin production in domestic chicks

In contrast to the situation in mammals, in which circadian melatonin production by the pineal gland does not begin until some time after birth, the development of pineal gland rhythmicity is an embryonic event in the precocial domestic fowl. A distinct melatonin rhythm was found in 19-d-old chick embryos maintained under light:dark (LD) 16:8. No significant variation in melatonin levels was detected in embryos exposed to LD 8:16. The melatonin rhythm in the pineal gland and plasma of chick embryos incubated for 18 d in LD 12:12 persisted for 2 d in constant darkness indicating that melatonin production is under circadian control at least from the end of embryonic life. A 1-d exposure to a LD cycle during the first postembryonic day was sufficient to entrain the melatonin rhythm, and previous embryonic exposure to either LD or constant darkness (DD) neither modified this rapid synchronization nor did it affect the melatonin pattern during the two subsequent days in DD. It is suggested that, in contrast to the situation in mammals, the avian embryo has evolved its own early circadian melatonin-producing system because, as a consequence of its extrauterine development, it cannot use the system of its mother.

African trypanosomiasis in the rat alters melatonin secretion and melatonin receptor binding in the suprachiasmatic nucleus

Rats infected with Trypanosoma brucei brucei, a subspecies of the extracellular parasites that cause African sleeping sickness, were examined for disturbances in the circadian rhythms of melatonin secretion (evaluated by determination of the excretion of melatonin in the urine) and the binding of melatonin to its receptor in the suprachiasmatic nuclei of the anterior hypothalamus. In normal and infected rats, Cosinor analysis showed a significant nocturnal peak. The amplitude of this peak was, however, significantly decreased in the infected rats. The peak of melatonin receptor binding in the suprachiasmatic nuclei showed a 4-h phase advance in the infected rats, compared with the controls (0400 and 0800, respectively). These data point to a disturbance in the circadian rhythm of the melatonin-generating systems in the pathogenesis of African sleeping sickness.

Effect of modafinil on plasma melatonin, cortisol and growth hormone rhythms, rectal temperature and performance in healthy subjects during a 36 h sleep deprivation

Modafinil is an alerting substance which has been used successfully to treat narcolepsy. Nothing is known about its effect on hormone secretions. For this purpose, eight healthy young men were enrolled in a double blind trial to test the effects of modafinil on daily plasma melatonin, cortisol and growth hormone (GH) rhythms. Blood was sampled for hormone assays, every hour during the daytime and every 30 min during the nighttime. In addition, rectal temperature and mental performances were determined during the study which comprised 3 sessions, two weeks apart: a 24 h control session including a night with sleep (S1) and two 48 h sessions S2 and S3 with a sleep-deprived night (N1) followed by a recovery night (N2). Modafinil (300 mg x 2) or placebo were randomly attributed during N1 at 22 h and 8 h. As expected, performance was improved after modafinil administration and body temperature was maintained or increased. Plasma melatonin and cortisol profiles were similar after modafinil and placebo administration. The levels observed during the recovery and the control nights (N2) displayed no difference. For GH, during both sleep deprived nights, secretion was dramatically reduced compared with the control one, although the number of secretory episodes was unchanged. These data show that the alerting property of modafinil is not related to an alteration of hormone profiles and suggest that the acute modafinil administration is devoid of short-term side-effects.

Development of rhythmic melatonin synthesis in cultured pineal glands and pineal cells isolated from chick embryo

The chick pineal gland exhibits circadian rhythms in melatonin synthesis under in vivo and in vitro conditions. A daily rhythm of melatonin production was first detectable in pineal glands isolated from chick embryos at embryonic day 16 and incubated under a LD cycle. All pineal glands isolated from 17-day-old and older embryos were rhythmic while no gland isolated at embryonic day 14 and 15 exhibited a daily rhythm in melatonin synthesis. Melatonin production in static cultures of embryonic pineal cells was rhythmic over 48 h if the cells were kept under a LD cycle. When embryonic pineal cells were incubated in constant darkness the rhythm in melatonin production was damped within 48 h. These results suggest that chick pineal cells from embryonic day 16 onwards are photosensitive but that the endogenous component of the melatonin rhythm is not completely developed at that age. A soluble analogue of cAMP stimulated and norepinephrine inhibited melatonin synthesis in cultured embryonic pineal cells. These findings indicate that the stimulatory and inhibitory pathways controlling melatonin synthesis in the mature pineal gland are effective in pineal cells isolated from chick embryos at least 2 days before hatching.

Effects of aging on the diurnal pattern of water intake in rats

This study was undertaken to confirm previous findings that Long-Evans rats exhibit age-related changes in the diurnal/nocturnal distribution of water intake and to examine the circadian pattern of these age-related changes. Twenty-one aged and 10 young pathogen-free rats were continuously monitored for water consumption over 12:12 h light/dark cycles. ANOVA, profile analysis, and cosinor analysis each demonstrated that aged rats differed from young rats. The age-related changes in circadian pattern can be described as a blunted rhythm (decreased amplitude) and an altered timing of peak activity (advanced acrophase). These differences, however, were only apparent in a subset of aged rats with the remaining aged rats exhibiting a circadian pattern indistinguishable from that of the young group.