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PubMed1994

Apparent lack of seasonal variation in implantation rates after in-vitro fertilization.

It has been suggested that seasonal variation in endometrial receptivity may occur in women, which could affect the likely success of in-vitro fertilization (IVF) treatment. We therefore studied implantation rates (fetal sacs as a proportion of embryos transferred) as an indirect index of receptivity in a narrowly defined population of women under 40 years old with normal ovulatory cycles and normal uterus and men with normal sperm function. A total of 577 cycles of IVF treatment were undertaken using a standard protocol of pituitary desensitization and ovarian stimulation during the 3 years 1990-1992. Results were compared between calendar months and 3-month seasons. The overall implantation rate was 14.9% of embryos, and the clinical pregnancy rate was 30.3% of cycles reaching egg collection. There were no significant differences in the monthly rates of eggs collected, fertilization and cleavage, or embryos transferred. Implantation rates varied to a greater extent but analysis of variance showed no seasonal variation. These findings do not support a seasonal variation in ovarian responsiveness or endometrial receptivity when stimulated for IVF treatment, but larger studies are needed for firm conclusions to be drawn.

Adult↗
PubMed1991

Seasonal variation in bone metabolism in young healthy subjects.

Serum vitamin D metabolites and urinary calcium excretion; parameters of bone formation (serum alkaline phosphatase, serum osteocalcin); parameters of bone resorption (24 hour hydroxyprolinuria, 2 hour fasting urinary hydroxyproline/creatinine ratio); and parameters of cortical and trabecular bone density, parathyroid hormone (iPTH, COOH terminal assay), and serum minerals (calcium, phosphorus) were followed serially in 55 young adults (21 women and 34 men) from December 1985 until January 1987 at four different times during the year. The effect of a low-dose cyclooxygenase inhibitor (piroxicam 5 mg daily) on the same parameters of bone density and bone turnover when given from December until May, was also evaluated in this study. At the end of the treatment period parameters of bone turnover and bone density were comparable between placebo and piroxicam-treated groups. Therefore, the results of all subjects were pooled in order to investigate seasonal variation. In both sexes, seasonal variation was found not only for 250HD3 but also for 1,25(OH)2D3, serum calcium and phosphorus, urinary calcium excretion, and for bone density at the lumbar spine. Parameters of bone formation (serum osteocalcin and alkaline phosphatase), bone resorption (24 hour urinary hydroxyprolinuria and fasting urinary hydroxyproline/creatinine ratio) and PTH were influenced by this seasonal variation. We conclude that in young adults, a significant seasonal variation occurs, with low winter and high summer values, for serum 25 and 1,25(OH)2D3 for urinary calcium apparently without important influence on parameters of bone turnover or parathyroid activity and for lumbar spine density. Treatment with a low-dose cyclooxygenase inhibitor was without influence on the observed changes.

Adult↗
PubMed1995

[The mode of onset of rheumatoid arthritis and seasonal variations].

The aim of the study was to establish age and sex distribution, seasonal variations, and mode, of onset in a sample of patients with rheumatoid arthritis. One hundred eighty nine patients (146 women and 43 men), whose age ranged from 18 to 77 yrs. (mean age 49.1, SD 12.93) were included in the survey. In majority of patients the disease started between 31-50 years, whereas in the age group from 21-30 it occurred more frequent in women, and in the age group from 51-60 in men. The onset of rheumatoid arthritis was in almost equal proportions acute or insidious, regardless sex. No difference was found concerning onset of the disease and seasonal variations. However there was a statistically significant correlation between mode of the onset and seasonal variations (P < 0.05). Rheumatoid arthritis started abruptly more often in springtime, and more insidiously in autumn, whereas in summer and winter there was an equal number of patients with acute or insidious onset of the disease.

Adolescent↗
PubMed2002

Seasonal variation in respiratory syncytial virus chest infection in the tropics.

Respiratory syncytial virus (RSV) is the most important cause of lower respiratory tract infection (LRTI) in young children. We determined if there was a seasonal variation in Malaysia in the incidence of RSV infection in young children admitted with LRTI, and possible associations of RSV infection with local meteorological parameters. A total of 5,691 children, aged less than 24 months and hospitalized with LRTI (i.e., bronchiolitis and pneumonia) between 1982-1997, were included in this study. Nasopharyngeal samples were collected and examined for RSV by immunofluorescence, viral culture, or both. Seasonal variations were determined by analyzing the monthly RSV-positive isolation rate via time series analysis. Possible correlations with local meteorological parameters were also evaluated.RSV was isolated in 1,047 (18.4%) children. Seasonal variations in RSV infection rate were evident and peaked during the months of November, December, and January (test statistics [T] = 53.7, P < 0.001). This seasonal variation was evident for both bronchiolitis and pneumonia categories (T = 42.8 and 56.9, respectively, P < 0.001). The rate of RSV infection appeared to correlate with the monthly number of rain days (r = 0.26, P < 0.01), and inversely with the monthly mean temperature (r = -0.38, P < 0.001). In the tropics, seasonal variations in the incidence of RSV infection are evident, with an annual peak in November, December, and January. This information provides a guide for healthcare provisions and implementation of RSV prevention.

Humans↗
PubMed1994

Seasonal variation in 25-hydroxyvitamin D and parathyroid hormone concentrations in healthy elderly people.

Seasonal variation in serum 25-hydroxyvitamin D and parathyroid hormone concentration was examined longitudinally in 96 community-dwelling men and women aged 65-74 years. Mean 25-hydroxyvitamin D concentration was lowest in winter (22.7 mmol/l) and highest in summer (35.4 mmol/l); mean parathyroid hormone concentration was highest in winter (3.55 pmol/l) and lowest in summer (3.24 pmol/l): these seasonal variations were highly significant (p < 0.0001). Parathyroid hormone concentrations were inversely related to 25-hydroxyvitamin D concentrations (p < 0.0001). Seasonal variation of 25-hydroxyvitamin D and parathyroid hormone concentration is marked in older healthy adults in Britain. Even in summer, mean 25-hydroxyvitamin D concentrations are low; maintaining more optimal vitamin D levels in the general population may have clinical and public health benefits.

Aged↗
PubMed1990

Seasonal variation of thermophilic campylobacters in sewage sludge.

The seasonal variation of thermophilic campylobacters in Lancaster's sewage sludge was studied over a 21 month period. The numbers in fresh sludge (from primary sedimentation) vary between approximately 200 and 5000/100 ml for most of the year but there was a large increase in May and June (in May 1988 there were 42,100 campylobacters/100 ml which is 17 times more than in the preceding April). In 1989 there was a similar May/June peak but with lower numbers. This seasonal variation, measured by environmental monitoring, reflects the incidence of infections in the community. The same pattern was found in 2-d old sludge but the numbers were substantially lower (40% lower over the experimental period). Thermophilic campylobacters were virtually absent from digested sludge and sludge prior to land distribution. Survival experiments confirm that campylobacters survive for only a few hours in both sterile and unsterile digested and undigested sludge. These results suggest that it is safe to dispose of Lancaster's digested sludge on land but there is still uncertainty about the ability of campylobacters to survive in sludge in the viable but non-culturable form.

Bacterial Typing Techniques↗
PubMed1986

Female rats in a laboratory display seasonal variation in fecundity.

Female laboratory rats housed in controlled environments of two separate laboratories displayed seasonal variation in fecundity. Fecundity peaked between May and August and reached a trough between December and February, as measured by oestrous cycle length, variability and regularity, as well as number of animals mating and the percentage of litters reared to weaning. The percentage of mated animals giving birth remained constant throughout the year. Seasonal variations in the laboratory coincided with the seasonal cycle reported for wild rats in natural conditions. Several environmental variables, e.g. food, water, humidity and airborne factors, were evaluated as putative cues for seasonal variation.

Animals↗
PubMed2002

Seasonal variation, hip fracture and vitamin D levels in Southern Tasmania.

AIMS: To determine the frequency of vitamin D deficiency in older patients admitted with a hip fracture and to look for seasonal variation in vitamin D levels and hip fracture in Southern Tasmania. METHODS: This was a case series of patients admitted to the Royal Hobart Hospital, Tasmania with a hip fracture from July 1996-June 1997. Information was collected on demographic data, functional activity, associated medical disorders and drug history. RESULTS: There were 91 patients, 66 female with a mean age of 81.3 years. Vitamin D deficiency, defined as a serum 1,25 hydroxyvitamin D level <28 nmol/L was present in 67% of subjects. Vitamin D levels were low throughout the year without significant seasonal variation. There was no seasonal variation in admissions with a hip fracture. The majority of patients (68%) either lived in institutional care or were dependent on a carer and 43% reported going outdoors less than once a week. CONCLUSIONS: The high incidence of vitamin D deficiency in these subjects admitted with a hip fracture reflects reduced sunlight exposure and poor diet and is probably a marker of frailty. The absence of seasonal variation reflects a frailer population likely to be housebound, less mobile and more likely to have falls and sustain a fracture. Older and frailer people may benefit from routine screening for vitamin D deficiency, and replacement therapy should be considered for those found to be deficient.

Age Distribution↗
PubMed1996

Seasonal variation in the incidence of peptic ulcer and esophageal variceal bleeding in Taiwan.

BACKGROUND: Seasonal variation of peptic ulcer and peptic ulcer bleeding has been reported in many western countries. To investigate the seasonal variation of peptic ulcer (PU) and esophageal variceal (EV) bleeding in Taiwan, this retrospective study was conducted. METHODS: Seven hundred and forty-six cases of gastric ulcer (GU) bleeding, 777 cases of duodenal ulcer (DU) bleeding and 264 cases of EV bleeding were recruited from January 1, 1991 to December 31, 1992. Patients were sent to the Medical Emergency Room (MER) for hematemesis and/or melena. Upper gastrointestinal (UGI) endoscopic examinations were completed within 24 hours for all patients. RESULTS: Significant seasonal variation was found in the incidence of PU and EV bleeding. PU bleeding was most often seen in March and EV bleeding was most often seen in February. CONCLUSIONS: The possible mechanism for the cyclic change of PU and EV bleeding is unclear, but clearly more manpower is needed during the months of February and March for better management of the increasing number of cases of PU and EV bleeding.

Aged↗
PubMed1981

Dynamics of insulin release by perfused edible dormouse (Glis glis) pancreas. Seasonal variations.

In order to characterize seasonal variations of beta cell function in the edible dormouse (Glis glis), the dynamics of insulin release were examined during perfusion of the isolated pancreas. The B cells exhibited biphasic insulin secretion; however, the dynamic response differed from that of the rat in that there was a steady-state second release phase. Glucose-induced insulin release changed according to the seasons. With 16.8 mmol/l glucose, the average insulin release of the late phase was 30.8 +/- 12.6 ng/min in winter, 7.4 +/- 3.2 ng/min in spring, 13.1 +/- 3 ng/min in summer and 23.3 +/- 4.4 ng/min in autumn. The glucose-induced insulin release, expressed as percent of the insulin content of the pancreas, varied according to the season: it represented 2.23 +/- 0.31% in winter, 1.28 +/- 0.10% in spring, 1.56 +/- 0.15 in summer and 2.6 +/- 0.11 in autumn. It is suggested that in spring and summer, the edible dormouse B cell secretion mechanism is less sensitive to glucose than in the other seasons.

Animals↗
PubMed1998

Seasonal variation of sweating responses under identical heat stress.

The seasonal variation of sweating responses under identical heat stress was investigated to make clear the seasonal acclimatization in daily human life on the experiments. The heat stress of 33 degrees C air temperature, 50% relative humidity laid in the experiments was chosen as a usual daytime condition in summer in metropolitan cities such as Tokyo and Osaka. Five subjects were exposed under the identical heat stress in the climate chamber every two months through the year. Results were discussed on the mean values for five subjects. Although the relation of skin temperature to daily mean air temperature showed a variation of high in summer and low in winter before the heat stress, it rose and showed almost constant value during the heat stress. The seasonal variation of tympanic temperature appeared a little before the heat stress, but disappeared during the heat stress. The seasonal variation of sweating responses was evident, that was high in summer and low in winter. The concluding remarks are as follows: 1) It could be considered that there is a seasonal acclimatization on the threshold temperature for sweat onset. 2) The seasonal acclimatization on sweating is supposed to be caused by the seasonal acclimatization of the threshold temperature. 3) The seasonal acclimatization on sweating could be comprehended in four stages corresponding closely to the daily mean air temperature (Ta). The 1st stage is December-April when Ta < 15 degrees C, the 2nd stage is April-August when 15 degrees C < Ta < 25 degrees C, the 3rd stage is the term centering on August when Ta > 25 degrees C and the 4th stage is August-December when 15 degrees C < Ta < 25 degrees C.

Adult↗
PubMedDate not supplied

Seasonal variation in diagnoses and visits to family physicians.

BACKGROUND: Practice-based research networks (PBRNs) replicating the National Ambulatory Medical Care Survey (NAMCS) must sample more than 1 year to account for presumed seasonal variation in illnesses. This study evaluated the effects of seasonality on diagnoses within NAMCS family physician data. METHODS: Using combined data from the 1995-1998 NAMCS, diagnostic clusters that accounted for more than 1% of total visits were analyzed for seasonality. Seasons were coded categorically as dummy variables with summer as the reference category. A logistic regression was performed with each diagnosis as an outcome on the full data. To examine the ability of alternative sampling strategies to replicate the full year of data, a simulation study was carried out drawing 50 samples of 1,000 visits each for winter-summer and spring-fall sampling periods. RESULTS: We found 23 diagnostic clusters that had a frequency more than 1%, of which 10 had seasonal variations (P < or = .001), primarily between winter and summer. If sampling were restricted to spring, the diagnostic clusters of pregnancy and coronary artery disease would account for less than 1% of visits. All other diagnostic clusters, though changing rank order, would account for more than 1% if sampled in a single quarter. In the simulated sampling strategy, visit prevalence dropped below 1% for at least 1 diagnosis in 24 of 50 samples in spring-fall compared with 20 of 50 samples for winter-summer (P > .20). CONCLUSIONS: There is little seasonal variation in the 23 diagnoses that occur in more than 1% of visits to family physicians. There is, however, important seasonal variation in the rank order of these diagnoses. A sampling strategy that uses any quarter of the year but spring (March, April, May) could be used to understand what diagnoses are frequently seen within a PBRN.

Adult↗
PubMed1994

[Analysis of the seasonal variations in mean birth weight and mean gestational period of 47 prefectures in Japan].

Seasonal variations of the mean gestational period (MGP) and mean birth weight (MBW) are examined by the traditional method of time-series analysis during the period from 1979 to 1983 in Japan. The results of the present study support the existence of a seasonal rhythm of MGP. Generally MGP showed a deep trough in winter and a shallow one in summer to early autumn. This pattern was similar to that of MBW. The two time series showed a statistically significant coincidence in their monthly fluctuations, and a statistically significant correlation was also observed for their amplitude. According to these results, we concluded that the seasonality in MGP plays an important role in creating the seasonality in MBW. However, the seasonality in MGP can not be the only definitive factor that totally regulates the seasonal variations in MBW. The relationship between the two time series is considered to be different among different seasons as well as regions. For example, we observed a decrease of the seasonal index in winter in the same month for both MBW and MGP, but not necessarily in summer. This suggests that the etiology of the decrease in seasonal variations is different between summer and winter.

Birth Weight↗
PubMed1996

[Seasonal variation and circannual rhythm of miniature end-plate potentials recorded from the neuromuscular junctions of the adult toad (Bufo bufo gargarizans)].

The seasonal variations and circannual rhythm of miniature end-plate potentials (MEPP) recorded from the sartorius neuromuscular junctions (NMJ) of 66 female and 62 male adult toads (Bufo bufo gargarizans) were studied with intracellular microelectrode recording techniques of electrophysiology. The results revealed that the mean amplitude of MEPP in each month of a year showed clear seasonal variation with a nadir in September and October and a zenith in March and April. This seasonal variation in MEPP amplitude was proved to be a circannual rhythm by single cosinor analysis and zero amplitude test, and the three parameters of the rhythm, i.e. mesor, amplitude and acrophase were 0.29 +/- 0.05 mV, 0.25 mV and -97.17 degrees in female toad and 0.19 +/- 0.02 mV, 0.16 mV and -92.01 degrees in male toad, respectively; the circannual rhythm in female toad was more distinct than that in male. Neither seasonal variation nor circannual rhythm was statistically significant in the changes of frequency of MEPP, regardless of toad sexuality.

Animals↗
PubMed1999

Seasonal variations and age-related changes in human sperm count, motility, motion parameters, morphology, and white blood cell concentration.

OBJECTIVE: To determine the presence of any seasonal variations and age-related changes in sperm parameters in andrology patients and fertile donors. DESIGN: Retrospective analysis. SETTING: University medical center andrology laboratory. PATIENT(S): The database of 2,065 semen analyses was retrospectively reviewed for the period of March 1, 1996, to October 31, 1998. INTERVENTION(S): None. MAIN OUTCOME MEASURES(S): The sperm count, motility, motile count, progressive straightline velocity, and percentage of rapid sperm were determined with the Hamilton-Thorne IVOS analyzer with standard setup parameters. RESULT(S): There were no significant seasonal differences in the patient's volume, sperm count, motility, motile count, whereas the percentage of rapid sperm and progressive straightline velocity were significantly lower in the spring. Correlation analysis of patient semen parameters versus age implied that as age increases there is a tendency for these semen parameters to decrease, whereas percent tail defects showed a significant positive correlation with age. CONCLUSION(S): Age-adjusted analyses of seasonal variations in andrology patient semen parameters showed significant seasonal variation in the percentage rapid motile sperm and straightline velocity, as well as the percent tail defects, percent immature sperm, and the percent tapered sperm. Such seasonal variations might prove to be clinically relevant and important when designing experimental protocols.

Adult↗
PubMed2006

A seasonal variation of calcitropic hormones, bone turnover and bone mineral density in early and mid-puberty girls - a cross-sectional study.

The importance of the seasonal variation of calcitropic hormones to growing skeleton has not been established. We studied whether there exists a seasonal variation in calcitropic hormones, bone mineral density (BMD) and bone remodelling markers in early puberty girls. One hundred and ninety-six girls, mean age 11.4 (sd 0.4) years, in Tanner stage 2 (early puberty) and 3 (mid-puberty) were studied during September to March. The BMD was measured from the lumbar vertebrae and the left femur by dual-energy X-ray absoptiometry. Their serum 25-hydroxyvitamin D (S-25-OHD), serum intact parathyroid hormone (S-iPTH), serum osteocalcin, urinary pyridinoline and urinary deoxypyridinoline were analysed from fasting samples. The concentration of S-25-OHD and serum osteocalcin differed among months (P < 0.01), reflecting a seasonal variation. The parathyroid hormone correlated negatively with S-25-OHD (r -0.325, P < 0.001). Moreover, the BMD in the femur (P = 0.047) and to a lesser extent in vertebrae (P = 0.057) differed between months in early puberty girls but this was not seen in mid-puberty. Seasonal variation in S-25-OHD and bone remodelling markers accompanied by negative correlation between S-25-OHD and S-iPTH was seen in this cross-sectional study of adolescent girls. In addition, the seasonal rhythm contributed 7.0-7.6 % difference in the BMD of lumbar vertebrae and left femur in early puberty girls. This variation should be avoided since it could hamper peak bone mass attainment.

Adolescent↗
PubMed2005

Seasonal variations in mental disorders in the general population of a country with a maritime climate: findings from the Netherlands mental health survey and incidence study.

Seasonal variations in the prevalence of mental disorders in general population surveys have rarely been noted. Using a representative sample of the Dutch population, the authors studied the seasonality of 1-month mental disorders and gender-by-season and age-by-season interactions. Data were obtained from the Netherlands Mental Health Survey and Incidence Study, a psychiatric epidemiologic study in which 7,076 adults aged 18-64 years were interviewed (1996) using the Composite International Diagnostic Interview. Seasonal statistical differences were not found for the category "any diagnosis", although prevalence was higher in winter (18.1%) and lower in summer (16.0%). Seasonal variations were also not found for the main categories "mood disorders", "anxiety disorders", "substance-use disorders", "eating disorders", and "schizophrenia". Some differences were found for individual disorders, mostly anxiety. Panic disorder was more frequently reported in winter than in summer, generalized anxiety disorder more frequently in winter than in other seasons, and obsessive-compulsive disorder more frequently in autumn than in summer. Only a few gender and age differences in seasonal variation were found. The authors conclude that there are only limited seasonal variations in mental disorders in general population studies, at least in countries with a mild maritime climate. For reliable estimation of the prevalence of some disorders, these findings have implications for the design of large-scale population studies.

Adolescent↗
PubMed1999

Seasonal variations in serotonin immunoreactivity and ultrastructure in the pineal organ of the Japanese grass lizard, with special reference to environmental temperature.

The seasonal variations in serotonin immunoreactivity and ultrastructure of the secretory rudimentary photoreceptor cells (SRPC) were studied in the pineal organ of the Japanese grass lizard, Takydromus tachydromoides in relation to the environmental temperature. Our results clearly demonstrated that serotonin immunoreactivity in the lizard pineal organ displayed seasonal variations under an artificial photoperiod of LD 12:12 and natural temperature in the laboratory. Immunoreactivity became intense with increase in temperature from spring to summer, showing the strongest reaction in the summer, and subsequently became weak with the drop in temperature to winter. Also, the SRPC of the lizard showed distinct seasonal variations in number and size of the dense-cored vesicles correlated to the serotonin immunoreactivity. In contrast, the changes in size of the lysosomes and nucleoli of the SRPC were inversely proportional to that of the dense-cored vesicles. Furthermore, the lysosomes ingested some dense-cored vesicles after the autumn, and they coalesced to form huge autophagosomes or residual bodies during the winter. The present study provided serotonin-immunohistochemical and ultrastructural evidence for seasonal variations in the secretory activity of the lizard pineal organ in accordance with changes in the environmental temperature. However, there may be few functional relationships between the pineal gland and the reproductive organs in the male Japanese lizard in relation to environmental temperature.

Animals↗