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PubMed1982

Seasonal variation of serum thyrotropin concentration and thyrotropin response to thyrotropin-releasing hormone in patients with primary hypothyroidism on constant replacement dosage of thyroxine.

Ten patients with primary hypothyroidism (aged 32--66 yr), replaced on constant daily doses of L-T4 (mean +/- SD, 1.90 +/- 0.22 micrograms/kg BW), were used to examine seasonal variations in serum levels of thyroid-related hormones for a period of 14 months. Basal and peak TSH concentrations after TRH (500 micrograms) were higher in winter than in summer. Summer values for basal TSH were all normal (normal range, less than 4.8 microU/ml), while winter values were supranormal in 5 of 10 patients. Summer values for peak TSH were subnormal or normal (normal range, 5.0--40.0 microU/ml), while winter values were supranormal in 3 patients, with the remaining values being normal [log basal TSH, 0.511 +/- 0.438 vs. 0.084 +/- 0.244 (P less than 0.05); log peak TSH, 1.394 +/- 0.410 vs. 1.017 +/- 0.423 (P less than 0.05)]. Serum resin T3 uptake, T4, free T4 index(FT4I), T3, free T3 index, and rT3 levels did not vary seasonally, although T4 and FT4I tended to fall in the winter. The summer and winter QKd interval (the interval from the onset of a QRS complex in the electrocardiogram to the appearance of the Korotkoff sound at diastolic pressure), basal metabolic rate, and serum cholesterol concentrations were all within the normal range. Basal and peak TSH after TRH were inversely correlated with serum T4 and FT4I levels. The basal TSH concentration was further inversely correlated with the seasonally altering ambient temperature. These results indicate that during the treatment of primary hypothyroidism with constant doses of T4, 1) serum TSH and its response to TRH show seasonal variation, 2) the hypersecretion TSH in the winter is related to small changes in serum T4 and FT4I levels, and 3) the seasonal variation in the serum TSH concentration may need to be taken into consideration when evaluating the adequacy of a T4 replacement dose.

Adult↗
PubMedDate not supplied

[Seasonal variation in sperm characteristics].

In all species, seasonal patterns in fertility are observed. In humans, seasonal variations of pregnancies are observed in spontaneous reproduction or in IVF. The most important factor seems to be sperm values and specially the morphology. Our study, on 188,075 cases (FIVNAT 1987-1995) shows significant variations of semen characteristics: we observe, in August, an improvement of sperm morphology.

Female↗
PubMed2001

Seasonal variation of antioxidant and biotransformation enzymes in barnacle, Balanus balanoides, and their relation with polyaromatic hydrocarbons.

Seasonal variations in the antioxidant enzymes (catalase, superoxide dismutase [SOD], NADH-DT diaphorase), biotransformation enzyme, glutathione-S-transferase (GST) and microsomal lipid peroxidation in digestive tissue of barnacle, Balanus balanoides, from polluted and non-polluted populations have been evaluated. Relationships with accumulated polyaromatic hydrocarbon (PAH) concentration in barnacle tissues and environmental parameters (water temperature, salinity, dissolved oxygen concentration, water pH) were determined. As a general trend, maximum antioxidant enzyme and GST activities were detected in the pre-monsoon period or summer (March-June) followed by a gradual decrease during the monsoon (July October) with a minimum in the post-monsoon period or winter (November February). This pattern was similar to tissue concentrations of PAHs, resulting in a significant positive correlation with antioxidant enzymes, mainly catalase and SOD. Microsomal lipid peroxidation exhibited an almost reverse trend of seasonal variation to that of antioxidant enzyme activities indicating an enhanced susceptibility of barnacle tissues to oxidative stress. Among the environmental parameters, only water temperature seemed to have a significant effect on observed variations of antioxidant enzymes and GST activities. The barnacles from polluted and non-polluted populations exhibited seasonal differences in the activities of all the enzymes studied, particularly catalase, SOD and GST, suggesting the possibility of some biochemical adaptation in organisms from a chronically polluted environment. The results indicated that antioxidant defense components, catalase and SOD, are sensitive parameters that could be useful biomarkers for the evaluation of contaminated aquatic ecosystems. The results also suggested the potentiality of barnacle, B. balanoides, as a bioindicator organism against organic pollution.

Animals↗
PubMedDate not supplied

Seasonal variation of births in Greece. Temporal changes and regional differences over a 24-year period.

The seasonal variation of birth rates in Greece was studied for the years 1956-1979. The relatively constant pattern of the period 1956-1974 (with peak in January and February) turned abruptly into a new one (peak in May-July) for the following years. Whereas the seasonal variation of the first period could be explained as an effect of sociocultural (religious) factors on the rate of conceptions, no explanation was found for its change or for the new pattern. Regional differences between NW and SE Greece were also studied. Seasonal factors and their changes were almost similar in both regions.

Birth Rate↗
PubMed2002

Seasonal variations of deep vein thrombosis and its influence on the location of the thrombus.

The role of season as a predisposing factor for the development of deep vein thrombosis is controversially discussed. We analysed retrospectively seasonal variations in the occurrence of deep vein thrombosis of the leg in 905 patients between 1996 and 2000. Additionally, we evaluated the relationship between the season and the location of the thrombus. Our study revealed that the frequency of deep vein thrombosis of the leg was significantly higher during the winter half than during the summer half (p < 0.001). Regarding the seasonal variation of the location of the thrombus, distal deep vein thrombosis was more frequent during the winter half while proximal deep vein thrombosis was diagnosed more often during the summer half of the year. In conclusion, we suggest that the season has an influence on the development of deep vein thrombosis in the leg as well as on the location of the thrombus.

Adult↗
PubMed2003

Measuring seasonality: psychometric properties of the Seasonal Pattern Assessment Questionnaire and the Inventory for Seasonal Variation.

There is a general consensus that seasonal changes in mood, behavior and vegetative functions vary in magnitude across the general population. Studying the dimension of seasonality requires reliable and valid measures. This study examined and compared the psychometric properties of the Seasonal Pattern Assessment Questionnaire (SPAQ) and the Inventory for Seasonal Variation (ISV) in 148 college students; 73 also completed a retest 2 months later. Results indicated good psychometric properties for both scales in terms of score distributions, test-retest reliability, internal consistency, factor structure and item-latent trait relationships using item response theory. Given the long history of its use and some small psychometric and simplicity advantages for the SPAQ, its continued use as a dimensional measure of seasonality is indicated.

Adolescent↗
PubMed2006

Seasonal variation and sex differences in the nutritional status in two local populations of wild Japanese macaques.

Seasonal variations and sex differences in the nutritional status in two local populations of wild Japanese macaques (Macaca fuscata fuscata) were examined. It was hypothesized that the ecological condition and/or reproductive strategies of each sex determine the nutritional condition and its seasonal fluctuation in each sex. Morphometric measures such as body mass, thoracic and femoris circumferences, skinfold thickness in four places (triceps, biceps femoris, subscapular, and abdomen), and wet mass of mesenteric and omental fat were used for comparisons between sexes, seasons, and populations. Animals of the Shimane population were larger than those of the Boso population in most morphometric measures, abdominal skinfold, and mesenteric and omental fat mass, suggesting environmental and/or genetic differences in the two populations. Females of both populations had larger skinfolds and mesenteric and omental fat mass than males, indicating that females had more fat than males. Females showed seasonality in most measures, having two peaks of body mass, thoracic and femoris circumferences, abdominal skinfold, and mesenteric and omental fat masses in early spring and late fall. In contrast, males exhibited no clear seasonal variations for most measurements, except for biceps femoris and subscapular skinfolds, which showed peaks in summer. Most morphometric measurements significantly correlated to each other, particularly in females, but most skinfolds had no correlation with other measurements. These findings suggest that sexual dimorphism in body composition and its fluctuation may be affected by the different reproductive strategies of males and females.

Adiposity↗
PubMed2003

Seasonal variations in the onset of childhood leukemia/lymphoma: April 1996 to March 2000, Shiraz, Iran.

Infection has long been suspected as a possible factor in the aetiology of leukemia and lymphoma, one of the most common malignancies in children. Since most viral infections have seasonal variations of onset, if seasonal trends in 1 month of diagnosis of leukemia and lymphoma could be proved, this would be supportive evidence for an infectious aetiology. A total of 367 cases in the Hospitals of Shiraz University of Medical Sciences, from April 1996 through March 2000, who were diagnosed as having acute lymphocytic leukemia (ALL), acute myeloblastic leukemia (AML), Burkitt's lymphoma (BL) chronic myeloblastic lymphoma (CML), Hodgkin's disease (HD) or non-Burkitt's type non-Hodgkin's lymphoma (NBNHL) were analysed. The month of appearance of the first symptom and the date of diagnosis were recorded. ALL demonstrated statistically significant monthly variation in the date of appearance of the first symptom (p < 0.05; peak in October) and the date of diagnosis (p < 0.05; peak in November). Seasonal variation was demonstrated in the date of the first appearance of symptoms in BL (p < 0.042), and in the date of diagnosis in AML (p < 0.049). There was no statistically significant seasonal variation in the month of diagnosis for other groups. Analysis based on the date of the first symptoms and the date of diagnosis for ALL patients, using summer-winter ratios, also showed a significant winter excess (p < 0.001). Our data provide modest support for an autumn-winter peak in the diagnosis of childhood ALL, underlying mechanisms that account for these patterns are likely to be complex and need more definitive studies.

Acute Disease↗
PubMed2000

Seasonal variation of Boophilus microplus (Canestrini, 1887) (Acari: Ixodidae) in cattle in Minas Gerais State, Brazil.

The seasonal variation of the tick Boophilus microplus in the 'Região Metalúrgica' region of Minas Gerais state was studied using 26 Bos taurus (Holstein) x Bos indicus (Gir) calves, of which 16 animals were 3/4 Holstein x 1/4 Gir and 10 were 3/4 Gir x 1/4 Holstein. Monthly tick counts were made between March 1996 and March 1998 and, although B. microplus infestations occurred throughout the year, they were greater during the rainy season. Rainfall was the climatic factor that most affected the seasonal variation. The animals with a preponderance of Holstein blood presented infestations that were significantly (p < 0.05) greater than those of the other cross. Five of the animals (19.2%) maintained 45.5% of the parasite load of the entire group.

Animals↗
PubMed1982

[Season variations in lipolysis activity of adipocytes from fox, badger and hedgehog].

1. We have studied the seasonal variations of the lipolytic response to a beta agonist, isoproterenol, and to theophylline of the isolated adipocyte from fox, badger and hedgehog, related to the circannual variations of testes and thyroid activities. 2. With the fox, we find a coincidence, in spring, between the maximum lipolytic sensitivity of the adipocyte, the thyroid function and the return to sexual rest. 3. With the badger, in winter, the maximum reaction of the adipocyte is contemporary with testes activity and with thyroid rest. 4. With the hedgehog, we observe two maximums in the sensitivity of the adipocyte to the lipolytic agents, one in spring, which coincides with the maximal testes and thyroid activities, the other in autumn, before the deep hibernation state. 5. In conclusion, there is, with these wild mammals, a seasonal variation in the lipolytic reaction of adipocyte which coincides with that of energy needs.

Adipose Tissue↗
PubMed2003

Seasonal variation in stroke in the Hunter Region, Australia: a 5-year hospital-based study, 1995-2000.

BACKGROUND AND PURPOSE: Seasonal variation in stroke has long been recognized. To date, there are minimal published data on seasonal variations in rates of stroke and subsequent case fatality in the Southern Hemisphere. The aim of this study was to examine stroke seasonality through the use of data from a hospital-based stroke register in the Hunter Region of New South Wales, Australia. METHODS: From July 1, 1995, to June 30, 2000, 3803 stroke events were registered in residents of the Hunter Region, New South Wales, Australia. We analyzed the trend of seasonal and monthly stroke attack rates and case-fatality rates using Poisson regressions with age and sex as covariates. RESULTS: Stroke attack rates were highest in the winter and lowest in the summer. From February (summer) to July (winter), there was a significant trend in increasing stroke attack rates (rate ratio, 1.07; 95% confidence interval, 1.05 to 1.10; P<0.001). This increase was seen mainly in those >or=65 years of age. Case-fatality rates showed similar trends with a 1- to 2-month lag compared with attack rates. CONCLUSIONS: There is an increase in stroke attack rates and case-fatality rate from summer to winter in the Hunter Region, Australia. These trends are similar to those found in the Northern Hemisphere.

Adult↗
PubMed2004

Time trends (1993-1997) and seasonal variation in body mass index and waist circumference in the Netherlands.

OBJECTIVE: To compare the time trend and seasonal variation in body mass index (BMI) and waist circumference. DESIGN: Continuous monitoring health survey carried out between 1 June 1993 and 31 May 1997. SUBJECTS: A total of 8,186 men and 9,638 women aged 20-59 y from three towns in the Netherlands. MEASUREMENTS: BMI and waist circumference. Obesity was defined as BMI > or =30 kg/m(2), abdominal obesity as waist circumference > or =102 cm for men and > or =88 cm for women. RESULTS: Levels of BMI and waist circumference increased between 1 June 1993 and 31 May 1997. Among women, the time trend in abdominal obesity was stronger than that in obesity. Further, levels of BMI and waist circumference were higher in winter than in summer seasons. The seasonal variation was larger for abdominal obesity than for obesity, among both men and women. CONCLUSIONS: The time trend in women and the seasonal differences in both men and women were stronger for abdominal obesity than for obesity. Surveys on BMI and waist circumference are only comparable if season is taken into account. Furthermore, the waist circumference is a more sensitive indicator of variations in lifestyle and body composition than is body mass index.

Abdomen↗
PubMed2002

Seasonal variations in nickel and vanadium in Mont Blanc snow and ice dated from the 1960s and 1990s.

Ni and V have been determined in snow and ice collected at a high altitude location (Col du Dôme) near the summit of Mont Blanc on the French-Italian border; dated from the 1960s and 1990s. Ni and V were simultaneously determined by inductively coupled plasma sector field mass spectrometry. Measured concentrations range from 6 to 700 pg g(-1) and 4 to 1,100 pg g(-1) for Ni and V, respectively. The results show pronounced seasonal variations in the concentrations of both metals, with high concentration values in summer layers and much lower values for winter layers. These seasonal variations are linked especially with the existence of inversion layers during winter months. Ni and V concentrations in excess of the contributions from rock and soil dust (Ni(excess), V(excess)) appear to be mainly associated with anthropogenic inputs, with pronounced seasonal variations. Large variations in the V(excess)/Ni(excess) ratio are observed, with a higher ratio in summer than in winter. This shows differences in anthropogenic inputs at Col du Dôme during the different parts of the year. The above ratio was compared with the corresponding ratios for oil combustion from stationary sources and the exhaust from gasoline and diesel engines. It appears that Ni and V concentrations at Col du Dôme are probably the result of changing combinations of contributions from oil combustion for power generation, industrial and residential uses, on one side, and automobile and truck traffic, on the other side, with possibly a significant contribution from Ni smelters in Russia during winter months.

Environmental Monitoring↗
PubMedDate not supplied

Seasonal variation in plasma cholesterol distributions: implications for screening and referral.

In 3,377 men and 3,900 women who participated in a community-based plasma cholesterol screening program, we found a significant cyclic time-trend in cholesterol levels, with maximum peak in January. The 95% confidence interval (CI) of the peak to trough distance was 5.8-13.8 mg/dL (0.15-0.36 mmol/L) in men, corresponding to 2.6%-6.3% of the average cholesterol level. Corresponding figures for women were 2.0-9.3 mg/dL (0.05-0.24 mmol/L) or 1.0%-4.6%. Applying the cutoff level for high cholesterol risk proposed by the National Cholesterol Education Program (< or = 240 mg/dL [6.21 mmol/L]) to sex-specific bimonthly distributions, we found a statistically significant variation in prevalence, attributable to seasonal trends, in men (P < .01), but not in women. In men, the age-adjusted prevalence in winter (25.4%) was double that in the summer (13.5%). Seasonal variation is an important determinant of the prevalence of hypercholesterolemia in men and should be considered in patient follow-up and screening.

Age Factors↗
PubMed1996

Seasonal variation of DNA adduct pattern in human lymphocytes analyzed by 32P-HPLC.

32P-HPLC is a recently published method to generate DNA adduct profiles after exposure to a complex of genotoxic substances. The low detection limit enables characterization of individual DNA adducts in the general population. The 32P-HPLC method was applied to human lymphocytes and granulocytes from Silesia, a polluted industrial region in the south of Poland. Human samples were collected at the end of winter and summer to investigate the seasonal influence on DNA adduct formation. In lymphocytes a strong seasonal variation was seen in total DNA adducts, with winter values exceeding the summer values by 7.33 +/- 3.56 times. Granulocytes did not show any seasonal variation. In winter-collected lymphocytes the DNA adduct levels were 21.4 +/- 16.6/10(8) normal nucleotides (NN) while the summer values were 2.96 +/- 2.46/10(8) NN. Granulocytes had 8.06 +/- 7.76 and 9.59 +/- 6.19 DNA adducts/10(8) NN during winter and summer respectively. The lymphocyte DNA adduct profile consisted of at least 16 individual or clusters of DNA adducts. All 16 had a clear winter influence, with a winter:summer ratio of 1.6-15.3, indicating exposure to a complex mixture of genotoxic substances. The DNA adducts analyzed in human lymphocytes had retention times similar to DNA adducts generated by polycyclic aromatic hydrocarbons. The suggested candidates for DNA adducts displayed a similar seasonal variation in airborne particles to that found in DNA adducts in lymphocytes of humans living in the area. This is the first application of the 32P-HPLC method to analysis of DNA adducts in human tissues.

Air Pollutants↗
PubMed1981

Absence of seasonal variation in serum concentrations of 1,25-dihydroxyvitamin D despite a rise in 25-hydroxyvitamin D in summer.

The serum concentrations of the vitamin D metabolites 25-hydroxyvitamin D2 (25OHD2), 25-hydroxyvitamin D3 (25OHD3), and 1,25-dihydroxyvitamin D (calcitriol) have been measured in normal subjects whose ages varied from 18 months to 35 yr. Samples were obtained in all months of the year in order to assess the effects of season on serum concentration. During the months of April to September, 25OHD3 levels are higher than in the winter months. No seasonal variation in the 25OHD2 or calcitriol serum concentration was observed. Age-related differences in 25OHD2 and D3 concentrations did not exist. The levels of calcitriol are higher in adolescence and increase from 35 +/- 19 pg/ml (SD) at 1.5-10 yr of age to 54 +/- 21 pg/ml at 10-20 yr of age. In young adults, the levels fall again to 28 +/- 16 pg/ml. Accordingly, despite a seasonal variation in the precursor of calcitriol, the levels of this most active metabolite of vitamin D do not change in relation to sunlight exposure. This lack of seasonal variation is further evidence of the tight feedback regulation of calcitriol.

25-Hydroxyvitamin D 2↗
PubMed1987

Seasonal variation in the incidence of cutaneous malignant melanoma: an analysis by body site and histologic type.

A seasonal analysis of the incidence of cutaneous malignant melanoma was conducted to investigate the degree to which the increased frequency of cases diagnosed in the summer may be due to an artifact of increased ascertainment. The monthly incidence of 13,151 microscopically-confirmed cases of cutaneous malignant melanoma diagnosed between 1973 and 1982 among white residents of nine regions in the United States served by population-based cancer registries participating in the Surveillance, Epidemiology, and End Results (SEER) program was evaluated for the presence of seasonal trends. Except for nodular melanoma, there was substantial seasonal variation in the incidence of all histologic types. For the two most common categories, superficial spreading melanoma and melanoma not further classified as to histology (of which the majority are likely to be superficial spreading melanoma), the peaks in incidence at body sites which are likely to experience seasonal changes in clothing (upper limbs, trunk, legs) occurred in the summer and were of similar relative size to the peaks, located in the spring, at sites which are likely to experience little variation in clothing during the year (head, face, and neck). A summer peak was also observed for Hutchinson's melanotic freckle melanoma of the head, face, and neck. The presence of seasonal variation in the incidence of superficial spreading melanoma of the head, face, and neck suggests that increased ascertainment cannot by itself account for seasonal variation in the incidence of superficial spreading melanoma of other parts of the body.

Female↗
PubMed2004

Impact of seasonal variation, age and smoking status on human semen parameters: The Massachusetts General Hospital experience.

BACKGROUND: To investigate the relationship of human semen parameters with season, age and smoking status. METHODS: The present study used data from subjects recruited into an ongoing cross-sectional study on the relationship between environmental agents and semen characteristics. Our population consisted of 306 patients who presented to the Vincent Memorial Andrology Laboratory of Massachusetts General Hospital for semen evaluation. Sperm concentration and motility were measured with computer aided sperm analysis (CASA). Sperm morphology was scored using Tygerberg Kruger strict criteria. Regression analyses were used to investigate the relationships between semen parameters and season, age and smoking status, adjusting for abstinence interval. RESULTS: Sperm concentration in the spring was significantly higher than in winter, fall and summer (p < 0.05). There was suggestive evidence of higher sperm motility and percent of sperm with normal morphology in the spring than in the other seasons. There were no statistically significant relationships between semen parameters and smoking status, though current smokers tended to have lower sperm concentration. We also did not find a statistically significant relationship between age and semen parameters. CONCLUSIONS: We found seasonal variations in sperm concentration and suggestive evidence of seasonal variation in sperm motility and percent sperm with normal morphology. Although smoking status was not a significant predictor of semen parameters, this may have been due to the small number of current smokers in the study.

Journal Article↗