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PubMed1994

[A study on seasonal variation of epidemic cerebrospinal meningitis with circular distribution method].

In order to study the seasonal variation of epidemic cerebrospinal meningitis (ECM) incidence; the data of ECM incidence during the period 1959-1990 in Changde City were analysed with circular distribution method. The result showed that the seasonal variation was obvious. In 28 of these 32 years, the highest peak of the ECM incidence occurred in March. In 26 years, 95% of epidemic periods began from October to June of the next year. The annual incidence rate had positive correlation with the r value of circular distribution, negative correlation with angular deviation and no correlation with mean angle a. It is concluded that the annual incidence rate concerns with the seasonal variation and does not concern with the date of the highest peak.

China↗
PubMed1991

Seasonal variation of cerebrovascular diseases.

The seasonal variation in all admissions of all types of cerebrovascular disease within the West Midlands Region was examined between the years 1973-1980. There was a fluctuation for both sexes with a peak in winter, between the months of October and April; a trough was observed in late summer, in July and August. Multivariate analysis of the meteorological factors showed an association between hours of sunshine and intracerebral haemorrhage. The meterological variables were strongly correlated with each other making the selection of the most predictable variable to stroke difficult.

Cerebral Hemorrhage↗
PubMed1984

Seasonal variations in depression and osteoarthritis.

Seasonal variations in consultations for depression and osteoarthritis were discovered in the 1980 morbidity data of five London practices with a total of 32,524 patients. Depression showed a bimodal pattern similar to that described from hospital data and national suicide statistics, but not previously recorded from general practice. Osteoarthritis also showed a bimodal pattern, with peaks in spring and autumn; this came as a surprise and needs confirmation from other studies. It may reflect the known tendency of rheumatic symptoms to become worse when relative humidity and other climatic variables are at their most changeable.The number of patients recorded in the year as having both osteoarthritis and depression was significantly smaller than would have been expected by chance. This finding is probably due to selective attention in the consultation, since it is unlikely that one condition protects a patient from getting the other.

Depression↗
PubMed1987

Indole 3-acetic acid concentration in the leading shoot and living stem bark of Scots pine: seasonal variation and effects of pruning.

Seasonal changes in the concentration of indole-3-acetic acid (IAA) in the leading shoot and in the live tissue external to the xylem (living bark) of 2-3 m tall Scots pine (Pinus sylvestris L.) trees were observed over a period of three years. Both the leading shoot and the living bark showed a consistent pattern of seasonal variation in IAA content, with maxima of about 150 and 350 ng g(-1) (fresh weight), respectively. The IAA concentration in both tissues increased in late June at the time of shoot growth termination, decreased from late August, and by October reached a low value, which was maintained throughout the winter. Excision of current year shoots on the upper branches decreased the annual stem diameter increment without affecting the concentration of IAA in the living bark. However, excising the leading shoot, or girdling the mainstem beneath the leading shoot, caused a substantial reduction in the IAA content of the living stem bark.

Journal Article↗
PubMed1996

Seasonal variation in parameters related to coronary heart disease risk in young men.

Seasonal variation in the plasma lipids and lipoproteins is reported in the literature. Whether this variation is the result of changes in diet or other factors has not been adequately addressed. We investigated the effects of a controlled diet on the seasonal variation in the levels of plasma lipids and apolipoproteins and also on the excretion of urine metabolites of TXA2 and PGI2 in healthy males. Two well-controlled diet studies were conducted to evaluate effects of dietary fatty acids on plasma lipids (Studies 1 and 2; n = 33) and eicosanoid excretion (Study 2 only; n = 15). Participants consumed whole-food test diets in a randomized, four-period crossover design during each 26-day experimental period. A non-intervention control group also participated in each study (Study 1, n = 12; Study 2, n = 11). Blood was collected monthly and analyzed for plasma lipids and apolipoproteins A-1 (Apo A-1) and B100 (Apo B). Twenty-four hour urine samples were collected monthly only in Study 2 and analyzed for TXB2 and 6-keto-PGF1 alpha by RIA. Seasonal fluctuations were observed in all subjects in plasma Apo A-1 (zenith = July, with 95% CI June-July; P < 0.05) and Apo B (zenith = October, 95% CI September-November, P < 0.05). Although there was no significant variation in plasma cholesterol levels, the increase in Apo B is consistent with an increase in LDL particle number during the fall/winter. Additionally, excretion of both eicosanoid metabolites and the ratio of 6-keto-PGF1 alpha/TXB2 was markedly elevated in July (95% CI June-July, P < 0.001). Three seasonal fluctuations were observed both in participants who consumed a highly-controlled experimental diet and in the non-intervention controls. Thus, these results suggest a diet-independent seasonal variation in parameters thought to be involved in coronary heart disease risk status. An understanding of these variations is important not oly for clinical evaluation and metabolic study design issues, but more importantly, to clarify their clinical significance with the seasonal incidence of CHD events.

6-Ketoprostaglandin F1 alpha↗
PubMed2002

Organ-to-organ and seasonal variation in alkaloids from Crinum macowanii.

The distribution and seasonal variation of alkaloids from Crinum macowanii were investigated. The alkaloids lycorine, 1-O-acetyllycorine, crinine, powelline, crinamine, crinamidine, 3-O-acetylhamayne, 1-epideacetylbowdensine and cherylline were isolated from this plant using gas chromatography. Significant organ-to-organ variations were detected for the alkaloids crinine, lycorine, powelline, crinamidine, 3-O-acetylhamayne and crinamine. Crinine, crinamidine and 1-epideacetylbowdensine showed significant seasonal variation.

Alkaloids↗
PubMed2004

Seasonal variation in morbidity and mortality related to atrial fibrillation.

OBJECTIVE: To determine whether there is seasonal variation in hospitalisations and deaths due to atrial fibrillation (AF) and to examine possible contributors to such variability. METHODS: We used the linked Scottish Morbidity Record scheme, which provides individualised morbidity and mortality data for the entire Scottish population. RESULTS: Between 1990 and 1996, there were a total of 33,582 male and 34,463 female hospitalisations related to AF. Significantly more admissions occurred in winter compared to summer (P<0.0001). In women, the peak number of admissions (106 per day) occurred in December (12% more than average) and the lowest number (89) in June (6% less than average). The respective figures for men were 10% more (101), 2% less (90). In both sexes, the greatest variation occurred in those aged >85 years-peak winter rates being 35-39% higher than average. A similar phenomenon was evident in relation to mortality in these patients. The average number of men who died during December was 22% higher, and in August 12% lower, than average, P<0.001. In women, the equivalent figures were 28% higher (December) and 14% lower (August), P<0.001. The winter peak of AF admissions did not, however, coincide with the lowest temperatures, and other factors such as seasonal variation in respiratory infection, may account for the monthly variation observed in hospitalisations for AF. CONCLUSIONS: There is substantial seasonal variation in AF hospitalisations and deaths, particularly in the elderly.

Age Distribution↗
PubMed2004

Seasonal variations in hospital admissions due to aneurysmal subarachnoid haemorrhage in the state of Zurich, Switzerland.

INTRODUCTION: In clinical practice, the occurrence of aneurysmal subarachnoid haemorrhage (SAH) often coincides with a particular season. Our objective was to examine seasonal variations in hospital admissions due to aneurysmal SAH. METHODS: The study population consisted of 489 patients with aneurysmal SAH who were admitted to the Department of Neurosurgery, University Hospital of Zurich, Switzerland, between 1st of January 1996 and 31st of December 2002. Statistical significance of seasonal variation was determined by applying Roger's r test. RESULTS: Statistically significant seasonal variation was only found among patients younger than 60 years, showing a first peak in spring and second lower peak in autumn (Roger's r=6.89, p<0.05). A borderline significance was found in men younger than 60 years (Roger's r=5.96, p=0.051). A trend was observed in patients presenting with Fisher grade 1-2 (Roger's r=5.70, p=0.058). CONCLUSIONS: Previous studies from different countries have shown significant seasonal variations, with the peak period for aneurysmal SAH differing widely. There appears to be some link between aneurysmal SAH and the season of the year or variations in weather conditions. Further investigations are desirable to evaluate which weather or climatic parameters correlate well with SAH.

Adult↗
PubMed2000

Seasonal variations of blood pressure and overhydration in patients on chronic hemodialysis.

Blood pressure (BP) has a seasonal cycle in the general population and in patients undergoing maintenance dialysis, but the causes remain unclear. We studied the BP measurements recorded at fixed hours three times weekly from 1994 to 1997 in 102 hemodialysis patients. We obtained monthly averages of the following variables: predialysis mean BP, greatest overhydration (OH) estimated by predialysis body weight excess over dry weight, chronic OH estimated by the remaining postdialysis weight excess over dry weight, urea reduction ratio (URR) in dialysis, and monthly means for daylight span and outdoor temperature over the study period. Average BP in the population diminished over the 48-month period, associated with a decrease in chronic OH (r = 0.66; P < 0.0005) but independent of greatest OH. BP and chronic OH presented synchronous seasonal variations, with peaks in late autumn and early winter and troughs in summer. These biological rhythms were inversely related to the seasonal daylight span and outdoor temperature. Both BP and chronic OH periods were synchronous with the daylight annual cycle and preceded the seasonal variations of temperature by 1 month. Multiple regression analysis showed that chronic OH and daylight, but not URR or temperature, had a significant independent association with BP changes. These results show the existence of seasonal variations of BP in dialysis patients that are associated and synchronous with seasonal changes in chronic OH status. Both cycles depend on conditions influenced by the annual daylight span more than by external temperature.

Blood Pressure↗
PubMed2000

Absence of seasonal variation in Graves disease.

PURPOSE: To determine whether there is an identifiable pattern of seasonal variation in the onset of symptoms of orbitopathy and thyrotoxicosis in patients with Graves disease. METHODS: This retrospective, noncomparative case series reviewed 305 randomly selected office records of patients referred to one author (M.K.) for evaluation of Graves orbitopathy between July 1990 and June 1998. All patients met inclusion criteria for the diagnosis of Graves orbitopathy. During initial evaluation for orbitopathy, patients identified the date of onset of orbital symptoms as well as the earliest date of either onset of thyroid symptoms or documented thyroid abnormality. Patients were excluded from analysis of seasonal variation if they could not recall the month of symptom onset or were euthyroid. The onset of orbital symptoms and identification of dysthyroid state were analyzed by calendar month and season. The chronological relationship of the development of orbital and thyroid symptoms was evaluated. RESULTS: No significant seasonal variation appeared in the onset of orbital symptoms or identification of dysthyroidism. Out of 148 patients, 115 (78%) developed symptoms of orbital disease within 18 months of the identification of dysthyroidism. The most common presenting orbital symptoms were swelling of the lid or prominence of the globe. CONCLUSIONS: This study fails to provide evidence for a seasonal influence on the incidence of Graves disease and the associated orbitopathy.

Adolescent↗
PubMed1998

Lack of seasonal variation of symptoms in patients with chronic fatigue syndrome.

Several of the symptoms involved in chronic fatigue syndrome (CFS) such as fatigue, hypersomnia, hyperphagia, weight gain, and mood show seasonal variations in the general population. The aim of this study was to investigate whether patients with CFS experience seasonal fluctuations in these symptoms as well. Seasonal variation of symptoms was assessed in a group of 41 patients with CFS and 41 controls closely matched for age, gender, and city of residence. Participants were recruited across the US and were asked to complete the Seasonal Pattern Assessment Questionnaire (SPAQ) and the Profile of Mood States (POMS). CFS patients showed significantly lower scores on multiple SPAQ-derived measures as compared with controls. These included seasonal variation in energy, mood, appetite, weight, and sleep length. Patients also reported a significantly reduced sensitivity toward sunny, dry, and long days than controls. No association was noted between intensity of seasonal changes and severity of depressive symptoms. Patients with CFS exhibit an abnormally reduced seasonal variation in mood and behavior and would not be expected to benefit from light therapy.

Adult↗
PubMed1986

Factors contributing to the seasonal variation of Bacillus spp. in pasteurized dairy products.

The seasonal variation in the spoilage of pasteurized products, especially double cream, by spore-forming bacteria was due to a number of factors. By far the most important was the seasonal variation in the types of organisms isolated from raw milks. Psychrotrophic spore-formers predominated in the summer-autumn months and these strains were able to germinate rapidly and grow in refrigerated dairy products. There was evidence that the concentration of one or more factors which promoted germination of psychrotrophic strains of Bacillus spp. in milk was higher during the summer than in the winter. This again may contribute to seasonal differences in spoilage by spore-forming bacteria. Post-heat treatment contamination by spores of Bacillus spp. may also be more prevalent in the summer-autumn period and evidence was obtained that spores associated with post-pasteurization contamination could germinate and grow more rapidly than those introduced into the product from the raw material. Thus, the increased spoilage of pasteurized products by Bacillus spp. observed in the June to October period may be due to a combination of factors. The relative contribution that each makes is not easily resolved.

Animals↗
PubMed1993

Seasonal variation of serum concentrations of beta-carotene and alpha-tocopherol.

We studied the seasonal variation in serum concentrations of beta-carotene and alpha-tocopherol (HPLC) in 17,247 Finnish men who smoked. Month of blood sampling was a statistically significant determinant of serum concentration of beta-carotene in a regression model including age, body mass index, alcohol and fat intakes, total serum cholesterol, and daily cigarettes as covariates. The serum concentrations were lowest in April-June and highest in October-November. The 1.5-fold increase in the serum concentration of beta-carotene during the fall reflects the seasonality of dietary sources of carotenoids in Finland. The serum concentrations of alpha-tocopherol demonstrated no seasonal variation but remained close to 27.6 mumol/L throughout the year. The results indicate that the seasonal variation of serum concentrations of beta-carotene should be taken into account in long-term studies in which comparison of groups or individuals is based on serum concentrations.

Aged↗
PubMed2002

Annual rates of admission and seasonal variations in hospitalizations for heart failure.

AIMS: To investigate the annual hospitalization rate and seasonal variation in confirmed heart failure (HF) admissions. METHODS AND RESULTS: Records from all admissions to one hospital during 1 year with a HF diagnostic code were reviewed. From 1953 admissions, 595 were excluded because they did not fulfill the diagnostic criteria. A total of 1069 patients had 1358 admissions with confirmed HF. Mean age was 74.8 +/- 11.5 years, 42% were males. The admission data were matched with data from the municipal census with 537,666 people aged > or = 15 years. There were 2.5 admissions per 1000 for the adult population and 26.5/1000 in those aged > or = 80 years. There were 444 males and 625 females, giving a higher rate of admission for female patients 2.2/1000 vs. 1.7/1000 (P < 0.0001), although age adjusted rates in females were higher only for > or = 80 years. Echocardiogram was performed in 706 patients (66%), 325 (46%) had a normal ejection fraction. This proportion increased in females--64% vs. 29% males--and in older patients--55% in > or = 75 vs. 39% in < 75 years. Mortality during the first admission of 1996 was 8.3%. There was a seasonal variation in HF hospitalizations (P < 0.0001) peaking at 25% above average in January and dipping to 33% below average in August. CONCLUSION: The rate of HF admissions was 2.5/1000 with an elderly preponderance and a higher rate of admission in males < 80 years and in females > or = 80 years. A seasonal variation ranging from 25% above average in January to 33% below average in August was observed.

Adolescent↗
PubMed1992

Seasonal variations of semen quality in male goats: study of sperm abnormalities.

The type, frequency and seasonal variation of sperm abnormalities in male goats inhabiting in Mediterranean region were evaluated. Semen was collected twice a week with an artificial vagina from 9 10-month-old Murciano-Granadina male goats weighing 41 to 48 kg. Distal cytoplasmic droplets and acrosomal damage were the predominant abnormalities. Increase in age (10 to 27 months) did not reveal itself as a main effect on the occurrence of sperm abnormalities. All types of sperm abnormalities studied showed significant (P<0.01) seasonal variation. The poorest quality semen was collected during winter and spring. In spite of a seasonal variation in sperm quality, semen of Murciano-Granadina goats in the Mediterranean area is good all year long, since the proportion of abnormal spermatozoa was well within the accepted range for normal fertility.

Journal Article↗
PubMed1990

Seasonal variation in stroke incidence in Hisayama, Japan.

We investigated seasonal variation in the incidence of cerebral stroke among the general population aged greater than or equal to 40 years in November of 1961 in Hisayama, Japan. During the 24-year follow-up period, 311 cases of cerebrovascular diseases occurred. The date or month of onset was determined in 308 cases, of which 51 were classified as intracerebral hemorrhage, 223 as cerebral infarction, and 27 as subarachnoid hemorrhage. We observed a significant seasonality in the incidence of all stroke (p less than 0.01), of intracerebral hemorrhage (p less than 0.05), and of cerebral infarction (p less than 0.01), whereas subarachnoid hemorrhage had no significant seasonal pattern. Subjects less than 64 years of age showed a significant seasonal variation in the incidence of both intracerebral hemorrhage (p less than 0.05) and cerebral infarction (p less than 0.01). A significant seasonal pattern for the incidence of intracerebral hemorrhage was also noted among persons with hypertension (p less than 0.05) or a high serum cholesterol level (p less than 0.05), whereas such a pattern for cerebral infarction was documented among normotensive persons (p less than 0.05) and those with a low serum cholesterol level (p less than 0.01). In addition, the incidences of intracerebral hemorrhage and cerebral infarction were negatively correlated with mean ambient temperature (p less than 0.01 and p less than 0.05, respectively), and all stroke and intracerebral hemorrhage in men were significantly related to intradiurnal temperature change (p less than 0.05 and p less than 0.01, respectively). The significance of the seasonal occurrence of stroke is discussed in relation to relevant risk factors.

Cerebral Hemorrhage↗
PubMed1997

Seasonal variations of rheological and hemostatic parameters and acute-phase reactants in young, healthy subjects.

The incidence of cardiovascular diseases is increased in winter months. Recent studies have shown seasonal changes in plasma viscosity, fibrinogen, and factor VII activity with elevated levels during winter. An increase in these factors generates a "hypercoagulable state," which may lead to a rise in cardiovascular morbidity and mortality. It has been suggested that an increase in upper respiratory infections might be the underlying cause for the raised acute-phase reactants, in particular fibrinogen, during the winter season. We investigated seasonal variations of 26 parameters, determining blood rheology and hemostasis in 16 healthy volunteers (8 men and 8 women) aged 20 to 41 years. They were seen at monthly intervals over a period of 1 year. Seasonal variation with peak fitted values in the winter months was found for plasma viscosity (P < .001 for the seasonal difference), red blood cell deformability (P < .001), whole blood viscosity (P < .001), hemoglobin (P < .001), hematocrit (P < .001), mean corpuscular volume (P = .001), platelet count (P = .01), alpha 1-glycoprotein (P < .001), fibrinogen (measured by immunonephelometry; P < .001), plasminogen activator inhibitor-1 (P = .002), LDL cholesterol (P = .003), and triglyceride levels (P < .001). HDL cholesterol (P < .001) and cortisol (P = .001) showed inverse seasonal patterns, with a maximum during summertime. No statistically significant seasonal variations were seen for red blood cell aggregation, complement factor C4, total cholesterol, ceruloplasmin, haptoglobin, white blood cell count, and plasminogen. These data do not support the hypothesis that increased morbidity and mortality from cardiovascular diseases during winter may be mainly attributable to increased synthesis of acute-phase proteins due to infections. The cause for the seasonal variations in rheological and hemostatic parameters remains unclear and should be studied in more detail.

Acute-Phase Proteins↗
PubMed1998

Seasonal variations in the presentation and growth of thyroid cancer.

Seasonal variation has been described in the presentation and growth of several malignant tumours, including cancers of the breast, uterus, uterine cervix, urinary bladder, liver, lymphatic system and skin, although the mechanisms are not known. We herein describe a circannual rhythm for thyroid cancer (total = 2627), with significantly more cases presenting during the late autumn and winter. In a subset of these cases (127 papillary carcinomas), significant seasonal variations with highest values in autumn-winter were found for tumour diameter and proliferation indicators (S- and G2M-phase fractions). These results indicate the likelihood of a seasonal factor (or factors) of importance for the regulation and modification of tumour cell proliferation. When further clarified, this might be of relevance for the planning of diagnostic and therapeutic strategies.

Female↗