Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Seasonal Variation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources
PubMed2000

Seasonal variations in mood and behavior among Chinese medical students.

OBJECTIVE: The goal of this study was to estimate the frequency of seasonal variations in mood and behavior among Chinese medical students. METHOD: A total of 1,358 medical students were surveyed with Chinese versions of the Seasonal Pattern Assessment Questionnaire and the Beck Depression Inventory in Jining, China. RESULTS: The mean global seasonality score was 8.3 (SD=3.6) out of a possible 24; 81.7% (N=1,110) of the subjects reported some trouble adapting to changing seasons. Summer difficulties were more common than winter difficulties by a ratio of 3:2; estimated rates of summer seasonal affective disorder and subsyndromal seasonal affective disorder were 4.4% and 8.0%, respectively, compared with corresponding winter rates of 2.4% and 5.7%. CONCLUSIONS: These results suggest that seasonal variations in mood and behavior are common in China. The predominance of summer difficulties stands in contrast to that in most Western studies and is consistent with the only other published study performed in Asia.

Adolescent↗
PubMed1998

Seasonal variations in hospital admissions for affective disorders by gender and ethnicity.

Hospital admission statistics for depression and mania have shown significant seasonal patterns. The present investigation was conducted to establish the pervasiveness of the impact of seasons on mood disorder presentation at Birmingham (52 degrees North) by gender and ethnicity. Non-mood disorder admissions were examined as a control to determine the specificity of any seasonal variation to affective illness. Case notes for 992 admissions, during January-December 1995 inclusive, to an inpatient unit were reviewed retrospectively. Admission data were broken down by gender and into three ethnic groups: Asian, white and black. Seasonality in admissions for depression, bipolar disorder and non-mood disorders was tested by gender and ethnicity. Admission frequencies for depression showed significant seasonal pattern, with the incidence of depression being highest in winter. Total admissions, bipolar and non-mood disorders did not show any significant seasonal variability. A gender effect was evident on seasonality of admissions for affective illness, with significant winter peak for depression and summer peak for bipolar disorder in women only. The Asian group was the only ethnic group that showed significant seasonal variation in depression, with a greater number of depressive episodes in winter. Environmental variables were related significantly to the incidence of mood disorders. Specific seasonal effect for affective illness was evidenced by the non-existence of seasonality in other psychiatric disorders. The reverse seasonal pattern for depression and mania suggests a maladaptive response of vulnerable individuals to specific functions of seasons.

Adult↗
PubMed2001

Seasonal variations in variceal bleeding mortality and hospitalization in France.

OBJECTIVES: The circadian variation in portal blood pressure and in the diurnal incidence of variceal bleeding is well known, but the seasonal variation in variceal bleeding is still controversial. This report analyzes the seasonal variations in mortality and hospitalizations due to variceal bleeding in the French population. METHODS: All the deaths due to variceal bleeding that occurred from 1987 to 1996 (N = 13,514) and all adults discharged from French public hospitals for variceal bleeding from 1995 to 1997 (N = 17,026) were examined retrospectively. Cumulated monthly averages were expressed as the percentage above or below the average monthly value during the entire study period. RESULTS: Deaths due to variceal bleeding in France occurred with a clear annual periodicity and peaked in winter (December/January), both in the overall population and in subgroups defined by age and sex, except for women. The distribution of cumulative monthly deaths differed by 24%, with a peak (14% above average) in December and a trough (10% below average) in July (Roger's test: p < 0.001). Hospitalizations for variceal bleeding in French public hospitals followed a similar seasonal pattern (p < 0.001) with a winter-spring predominance (4% to 7% from December through April), except in patients aged 15-49 yr. There was a short sharp peak of mortality in early winter in French public hospitals. The seasonality of hospitalization and death increased markedly with age. CONCLUSIONS: A better understanding of these age- and sex-specific seasonal patterns would allow to improve pharmacological protection measures, disease management, and educational strategies.

Adolescent↗
PubMed1996

Seasonal variation in hospital admissions for chronic obstructive pulmonary disease in Finland.

BACKGROUND: Hospital admissions in general are characterised by a marked seasonal variation. We studied the periodicity in hospital treatment for chronic obstructive pulmonary disease (COPD) in Finland where the unfavourable climate with great climatic differences between summer and winter may play an important role in causing the seasonality in COPD hospitalisation. METHODS: Data by month were obtained for the years 1972-92 from the National Discharge Register, which contains information on patients treated in all hospitals in Finland. The search was concentrated on principal diagnoses conforming to International Classification of Diseases codes 491, 492 and 496. There were 182, 723 admissions of COPD patients aged 55 years or over during the period in question. Time series analysis was carried out on retrospective data over a 21 year period and analysed by two age groups (55-74 years or > 74 years) and gender. The autoregressive integrated moving average (ARIMA) model was used to analyse seasonality. RESULTS: The seasonality pattern showed a peak in winter (13.4% excess mean monthly admissions in January) and a trough in summer (10.0% deficit in below mean monthly admissions in July). This pattern was more prominent in women and in those aged 75 years or over. CONCLUSION: The cold winter together with an increased incidence of respiratory infections may be the most probable cause of the periodicity noted here. Due to the unfavourable northern climate even a greater seasonal variation was expected.

Aged↗
PubMedDate not supplied

Seasonal variation in AF-related admissions to a coronary care unit in a "hot" climate: fact or fiction?

BACKGROUND: Seasonal variations in atrial fibrillation (AF)-related morbidity and mortality have been demonstrated in "cold" northern European climates, but there are few data describing such a phenomenon in a "hot" climate. RESEARCH OBJECTIVE: To examine the pattern of AF-related admissions to a coronary care unit (CCU) in South Australia operating within a Mediterranean climate, and to determine potential differences according to mean daily temperatures. PATIENT COHORT AND METHODS: A total of 144 admissions to the CCU during the 30 hottest and coldest days (60 days in total) during the calendar year 2001 were analyzed in respect to the absolute number of admissions and the profile of those admitted during "hot" and "cold" days. RESULTS: Overall, there were significantly more admissions to the CCU on "cold" as opposed to "hot" days (90 vs 54 patients in 30 days, P < or = .001). Of the 24 patients found to be in AF on presentation to hospital, 18 (75%) were admitted on cold days (P < .05). Alternatively, during "hot" days, patients were more likely to be diagnosed with unstable angina rather than acute myocardial infarction (46% vs 30%, P = .07) with proportionately fewer patients in AF at the time (11% vs 20%, P = NS). CONCLUSIONS: These preliminary data suggest that the phenomenon of seasonal variations in AF-related morbidity extend beyond colder climates to hotter climates with sufficiently large relative (as opposed to absolute) changes in ambient temperatures during the year.

Aged↗
PubMed1996

Seasonal variation in the time to pregnancy: a secondary analysis of three Danish databases.

Three Danish databases were reanalysed to investigate seasonal variation in the time to pregnancy. Information was available on cohorts of women selected on the basis of union membership or residence in a given area: textile workers in Denmark (with 1,053 first and 1,771 second pregnancies), pharmacy assistants in Denmark (with 734 first and 725 second pregnancies) and pregnant women in the 36th week of pregnancy in two Danish cities (with 3,657 first and 3,526 second pregnancies). The influence of the season was of primary interest, because it is presumed to cause impaired ovarian function and hence a prolonged time to pregnancy. Furthermore, we studied whether the waiting time was prolonged in other situations with possibility of decreased ovarian function: in young and older women. In genera, seasonality in the time to pregnancy based on the time of conception was found with a higher chance of a prolonged waiting time before conceiving in February-April and a lower chance of a prolonged waiting time before conceiving in August-October. This association was not distorted by the age of the women or diabetes mellitus. A prolonged time to pregnancy was found in women of 30 years or older. Women of 20 years or younger did not have a prolonged waiting time, but most of them were well beyond the age of menarche and thus beyond the period of impaired ovarian function. On a population level, there was evidence for seasonality in the time to pregnancy, which is compatible with seasonal variation in pregnancy planning as well as with biological influences.

Adolescent↗
PubMed1986

Seasonal variation in food intake, pattern of physical activity and change in body weight in a group of young adult Dutch women consuming self-selected diets.

The effect of season on the energy balance was examined in 114 young adult Dutch women consuming self-selected diets. Energy intakes and patterns of physical activity were assessed monthly 14 times with the 24-h recall method. After this period of 14 months, in the second year the same estimates were made with intervals of 2-3 months to check if the seasonal variations observed were not accidental. The study did not demonstrate seasonal variations in the mean energy intake of the group under study. However, the intake of fat appeared to be higher in the winter and spring than in the summer and autumn, whereas for the intake of mono- and di-saccharides the reverse seemed to be true. The intake of dietary fibre was higher in the autumn than in the summer, with intermediate values for winter and spring. Small seasonal fluctuations were observed in body weight and time spent on various physical activities. On the one hand, these fluctuations are too small to indicate physiological significance, on the other hand they are wide enough to be taken into account in the design of many longitudinal studies on the relation between diet and disease.

Adult↗
PubMed1994

Investigation of the diurnal, ontogenetic and seasonal variation in the molluscicidal saponin content of Phytolacca dodecandra aqueous berry extracts.

Daily variation in the content of the saponins of the berries of Phytolacca dodecandra was determined in berries harvested at the full grown green unripe stage of development once every two hours. The saponin content was quantitatively determined by HPLC analysis of the molluscicidal monodesmosidic saponins in the aqueous extract of the crushed berries. No significant daily variations were observed in extracts of berries collected at different times of day (P > 0.05 by ANOVA). But, seasonal variation was apparent in extracts prepared from berries harvested from the same plants once every two weeks. Berries of highest saponin content were those harvested during the dry season and just before the onset of the rainy season. The seasonal variation was attributed to increased water stress during the dry season. Very young racemes had the highest saponin content, while mature berries produced the lowest saponin concentration. There was, however, consistency in the berry saponin composition during the day, season and all stages of berry development.

Carbohydrate Sequence↗
PubMed1995

Seasonal variation in NPY immunoreactivity in the suprachiasmatic nucleus of the jerboa (Jaculus orientalis), a desert hibernator.

Using immunocytochemical techniques the seasonal variation in NPY immunoreactive fibers was investigated in the suprachiasmatic nucleus of both male and female jerboas. During the period of sexual quiescence (autumn), the amount of NPY immunoreactive fibers in the suprachiasmatic nucleus of both male and female jerboas was higher than in the period of sexual activity (spring-middle of summer). Compared with the respective control groups, castration during the period of sexual activity and testosterone or estrogen supplementation in sexually inactive animals did not affect NPY immunolabeling. These results indicate that the seasonal variation observed in NPY immunoreactivity in the suprachiasmatic nucleus of the jerboa is independent of circulating levels of steroid hormones. The possible influence of another hormonal system or a direct influence of an external factor such as photoperiod on NPY content in the suprachiasmatic nucleus remains to be determined.

Animals↗
PubMed1988

Seasonal variation in bronchial reactivity in a community population.

Morbidity and mortality from asthma is increased during the grass-pollen season and during the autumn months in the United Kingdom. It is not apparent why this seasonal variation occurs nor whether the variation in morbidity and mortality is associated with variation in bronchial reactivity. We have measured bronchial reactivity on four occasions during 12 months in 60 subjects selected from a community population in the south of England. All subjects had had a histamine challenge test and skin tests to common antigens as part of a survey of asthma prevalence in March 1984. Further measurements of the provocative dose causing a 20% fall in FEV1 (PD20) were made at the peak of the grass-pollen season in June, at the end of September, and in the following March, and current symptoms of respiratory tract infection (RTI) were assessed on all four occasions. Geometric mean PD20 demonstrated significant seasonal variation between 1.38, 0.82, 0.92, and 1.20 mumol in March, June, September, and March, respectively (p less than 0.02). Relative to March 1984, PD20 was significantly decreased in June and September (p less than 0.005 and p less than 0.02, respectively) but not in March 1985 (p = 0.39). Within subjects atopy was significantly related to decrease in PD20 in September (p less than 0.05) and in March 1985 (p less than 0.025) but not in June (p = 0.40). Change in PD20 between occasions was unrelated to RTI symptoms, age, or smoking status, but it was related to change in baseline FEV1/FVC (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2005

Epistaxis: are temperature and seasonal variations true factors in incidence?

OBJECTIVE: To investigate the previously documented inverse association between ambient temperature and presentation rates for patients with epistaxis and seasonal variation of emergency presentation rates for patients with epistaxis. STUDY DESIGN: A retrospective analysis of all consecutive emergency patients with epistaxis presenting to hospital from the community over a five-year period, 1997-2002 (1830 days), including those who required admission to hospital with epistaxis over the same period. Patients in whom there was a clear aetiology for the epistaxis (traumatic, recurrent, iatrogenic, coagulopathic and hypertensive) were excluded. SETTING: A tertiary referral centre in south-west London serving a population in excess of 2.8 million. METHOD: A retrospective analysis of all patients presenting or admitted to St George's Hospital with epistaxis over a five-year period. Daily ambient temperature readings from London Heathrow airport were recorded for the same period. Presentations were correlated with monthly temperature variations and the month itself. Statistical analysis with Pearson's correlation coefficient was performed. RESULTS: 1373 patients with epistaxis presented to our department, of whom 386 (28.1 per cent) were admitted to hospital. No correlation is seen between ambient temperature and presentation rate for patients with epistaxis. No seasonal preponderance is noted for presentation rate (Pearson r = 0.160, p = 0.221) in this series. CONCLUSION: To our knowledge, this is the largest study to date examining ambient temperature association and epistaxis, and the first to investigate presentation rate in place of admission rate. We feel that the exclusion of all patients with epistaxis not admitted to hospital introduces a bias. In this series, there is no correlation between ambient temperature, seasonal preponderance, presentation rate or admission rate for patients with epistaxis. This is contrary to previously reported findings. We do not support the view that there is a relationship between epistaxis and temperature or seasonal variation. This contradicts the current belief that incidence of epistaxis displays seasonality, and has implications for the allocation of resources for healthcare provision within ENT departments.

Epistaxis↗
PubMed1994

Spatial and seasonal variation of major and trace elements in settling particulate matter in an estuarine-like archipelago area in the Northern Baltic proper.

This study describes the spatial and the seasonal variation of flux and concentration of 11 metals (Al, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Zn), organic matter and C and N in settling particulate matter collected with sediment traps during seven interconnective, continuous periods totalling 15 months. Ten sediment traps were placed out along the metropolis-affected fresh water outflow of Lake Mälaren, out through a non-tidal estuarine-like region with a low salt content, through the Stockholm archipelago to the Baltic. The metal concentrations of the particles were analysed with AAS using the flame technique and the amounts of C and N were determined with elemental analysis (CHN). The flux of particulate matter and of all metals decreased rapidly outwards in a gradient from the innermost stations. The distribution and composition of the particles were dominated by variations in the runoff from Lake Mälaren and by the seasonal dependence on primary production. However, they were also influenced locally by the supply of nutrients via water treatment plant effluents and probably by the special sedimentation conditions in the mixing zones and by resuspension. The concentrations of Cu, Hg, Pb and Cd in the interior of the area under investigation were the most elevated of the elements and decreased markedly further out in the archipelago, indicating local anthropogenic input. Zn, Cr and Fe also showed signs of supply from the urbanized environment. The flux of most of the metals studied displayed both spatial and seasonal correlation with the weight (TPM) of the material, whereas seasonal variation of Cd was correlated to its volume (TPV) and concentration of organic matter (POM, PC and PN).

Journal Article↗
PubMed2006

Lack of seasonal variation in idiopathic talipes equinovarus.

BACKGROUND: One proposed etiology of idiopathic talipes equinovarus is an in utero enterovirus infection. Enterovirus infections demonstrate seasonal variation in temperate climates. METHODS: We collected data on 1202 children with idiopathic talipes equinovarus born in the Northeastern United States, Midwestern United States, and the United Kingdom to investigate a seasonal variation in this congenital deformity. Birth date, gestational age at the time of delivery, gender, race, and laterality were tabulated and subjected to univariate and bivariate analyses. RESULTS: There were 774 boys and 428 girls with idiopathic talipes equinovarus. The birth location was the United Kingdom (458 children), the Midwestern United States (426 children), and the Northeastern United States (318 children). No significant differences were detected among the geographic groups with respect to gender, race, or laterality, and no variation in month of birth or month of conception was noted. CONCLUSIONS: This study does not support an in utero enterovirus infection as an etiology of idiopathic talipes equinovarus in industrialized populations.

Clubfoot↗
PubMed1992

Seasonal variations in the immune system of lower vertebrates.

Seasonal variation, affecting the structure and function of the ectotherm immune system, is an excellent 'natural' model of the influence of neuroendocrine rhythms on immunity. In this review, Agustín Zapata, Alberto Varas and Marta Torroba examine the correlations between seasonal changes and circulating steroid levels, and investigate the possibility of a neuroendocrine-immune network in lower vertebrates.

Adrenal Cortex Hormones↗
PubMed1997

Seasonal variations of solar UVB and UVA in Syria.

Seasonal variations of solar UVB (285-320 nm) and UVA (320-400 nm) were measured in three sites in Syria (33-37 N degrees) for 2 y: 1992-1993. UVB measurements were performed using polysulphone films and Robertson-Berger meters, while UVA measurements were done by a UVA intensity meter. Two sets of measurements were carried out: 1) Maximal daily doses 3 times per week (every other day); and 2) Diurnal variations from sunrise to sunset, every 1 h, twice per month (every fortnight).

Humans↗
PubMed1989

Seasonal variation in suicide: is there a sex difference?

Seasonal variation in suicide in Italy for the years 1969-81 has been assessed in males and females by means of harmonic analysis. Cyclical fluctuations in the number of suicides, reasonably consistent over the 13 years of the study, have been observed in both sexes. Seasonal harmonics accounted for 65.3 and 48.4% of the variance in male and female suicides respectively. While in males the only important seasonal harmonic was the first (one cycle per year), in females there was an important first harmonic and a second harmonic (two cycles per year). In both sexes the peak of the first harmonic occurred in May, while in females the subsidiary peak occurred in October-November.

Cross-Sectional Studies↗
PubMed2001

The role of cholecystokinin in the expression of seasonal variation in the feed intake and eating pattern of red deer (Cervus elaphus).

The role of cholecystokinin (CCK) in the expression of seasonal variation in feed intake and feeding activity in ruminants was investigated by active immunisation of castrated male red deer (Cervus elaphus). In April, animals of two groups (five animals per group) were immunised against either CCK or vehicle solution only and booster injections were administered at 2-month intervals for the following year. Measurements were conducted for a period of more than a year from July. There were no significant effects of immunisation on mean daily food intake. However, there was a significant interaction (P<.01) between immunisation and month (season), with respect to rate of feed ingestion during meals, with animals immunised against CCK exhibiting higher mean rates of ingestion during October to May but lower mean rates during June to September. It is concluded that systemic CCK has a role in the expression of seasonal variation in the rate of feed ingestion during meals in ruminants and that this, in turn, may affect the pattern of seasonal change in daily feed intake. Since there was no evidence of differences with treatment in profiles of insulin, growth hormone (GH), thyroxine (T(4)), triiodothyronine (T(3)), insulin-like growth factor-1 (IGF-1) or prolactin, it is unlikely that this effect is expressed through changes in the profiles of these hormones.

Animals↗
PubMed1986

Seasonal variation of births in rural southwestern Nigeria.

A total of 12 708 live births registered between 1965 and 1975 in Igbo Ora, a rural area in southwestern Nigeria, were examined for seasonal variation using trigonometric regression analysis. The monthly number of registered births showed a significant seasonal pattern with a peak in May and corresponding minima in November. The extent of the seasonal variation above and below the annual mean was about 7%. There has been no significant shift in both the month of peak occurrence and the magnitude of the variation within the 11-year period of study. It is thought that the observed seasonal pattern may be related to climatic factors as well as sociocultural patterns of life associated with cyclical farming activities characteristic of a predominantly agricultural community.

Birth Rate↗