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PubMed2001

Plasma homocysteine is not subject to seasonal variation.

BACKGROUND: Studies investigating the relationship between plasma total homocysteine (tHcy) and vascular disease usually rely on a single measurement. Little information is available, however, on the seasonal variability of plasma tHcy. The aim of this study was to investigate the seasonal variation in fasting plasma tHcy and related B-vitamin intake and status in a group of people who did not consume fortified foods or take B-vitamin supplements. METHODS: In this longitudinal study, a group of 22 healthy people were followed for 1 year. A fasting blood sample and dietary information were collected from each individual every 3 months, i.e., at the end of each season. RESULTS: There was no significant seasonal variation in plasma tHcy or in B-vitamin intake or status with the exception of red cell folate (significantly lower in spring compared with autumn or winter) and serum folate (significantly lower in spring compared with the other seasons). Although the between-person variation in plasma tHcy was high (47%), the within-person variation was low (11%). This low variation, combined with the low methodologic imprecision of 3.8%, yielded a high reliability coefficient for plasma tHcy (0.97). CONCLUSIONS: Although there was a small seasonal variation in folate status, there was no corresponding seasonal variation in plasma tHcy. The high reliability coefficient for plasma tHcy suggests that a single measurement is reflective of an individual's average plasma tHcy concentration, thus indicating its usefulness as a potential predictor of disease. This, however, needs to be confirmed in different subgroups of the population.

Adolescent↗

PubMed1991

Seasonal variations in urinary risk factors among patients with nephrolithiasis.

Twenty-four hour urine specimens from 5,677 stone-forming patients throughout the United States were analyzed for seasonal variations in urinary risk factors for nephrolithiasis. Determinations were performed for urine volume, pH, calcium, oxalate, phosphorus, sodium, magnesium, citrate, sulfate, uric acid, and the relative supersaturation (RS) of calcium oxalate, brushite, monosodium urate, and uric acid. Criteria for significant seasonal variation included a significant difference in monthly means of risk factors, seasonal grouping of the data by the Student-Newman-Keuls multiple range test, consistent year-to-year trends and a physiologically significant range. Minimum urine volume of 1.54 +/- 0.70 SD L/day occurred in October while a maximum urine volume of 1.76 +/- 0.78 SD L/day was observed during February. Minimum urine pH of 5.94 +/- 0.64 SD was observed during July and August while a maximum pH of 6.18 +/- 0.61 SD was observed during February. Daily urinary excretion of sodium was lowest during August, 158 +/- 74 SD mEq/day and highest during February 177 +/- 70 SD mEq/day. The RS of brushite and uric acid were found to display significant pH-dependent seasonal variation with a maximum RS of uric acid 2.26 +/- 1.98 SD in June and a low of 1.48 +/- 1.30 SD in February. Maximum RS of brushite 2.75 +/- 2.58 was observed during February. Minimum RS of brushite 1.93 +/- 1.70 SD was observed in June. Phosphorus excretion displayed seasonal variation about a spring-fall axis with a maximum value 1042 +/- 373 SD mg/day in April and a minimum value of 895 +/- 289 SD mg/day. Urine volume, sodium, and pH were significantly lower during the summer (June, July, August) than in the winter (December, January, February). The RS of uric acid was higher, but that of brushite and monosodium urate was lower in the summer than in the winter. The seasonal changes observed in urine volume, pH, sodium, and the RS of brushite and uric acid are consistent with summertime sweating and increased physical activity. Seasonal variations in phosphorus excretion are probably dietary in origin. The summertime was characterized by an increased propensity for the crystallization of uric acid but not of calcium oxalate or calcium phosphate.

Calcium↗

PubMed2001

The impact of traditional management on seasonal internal parasite burdens and productivity of indigenous Tswana goats in southern Botswana.

Data collected monthly over a period of two years were live weight, packed cell volume (PCV), nematode faecal egg counts (FECs) and coccidial oocyst counts from faecal analyses for 100 mixed age (3-7 years) indigenous Tswana does. The aims of this experiment were to determine seasonal FECs and coccidial oocysts in these goats and quantify the relationships of these burdens to liveweight and PCV. FECs significantly (P < 0.05) varied with season, with the warmer seasons viz spring, summer and autumn having higher log (x + 1) parasite burdens than the cooler winter, while seasonal trends for coccidial oocysts were not obvious. PCV was also significantly (P < 0.05) lower in the warmer seasons than winter. FECs and coccidial oocysts in all seasons were less than the mean log (x + 1) of 3.3 inferred to reduce production in small stock. Correlation coefficients were strongly negative: -0.95 for FECs and liveweight and -0.84 for FECS and PCV, indicating that these worms had a negative impact on productivity. A further study should be conducted to quantify the effects of controlling these parasites during the warm seasons on productivity.

Animals↗

PubMed1975

Histochemical studies on the mucosubstances in the ovotestis of a hermaphrodite land pulmonate Semperula maculata in seasonal breeding-aestivation cycle.

With a view to augment the cytochemical localization characterization and, probable functional significance of mucosubstances in the ovotestis in the reproductive physiology of land pulmonates, the mucosubstances were investigated in the ovotestis of a land snail, Semperula maculata (Stylommatophora) in the seasonal breeding-aestivation cycle. Widely accepted, recent and well-established histochemical techniques were emoloyed. The results showed that the cells in the germinal epithelium of the follicular wall, were endowed with a capacity of synthesis of neutral muco-substances. They also contained glycogen. The nurse cells contained neutral mucosubstances and glycogen in them, while maturing ovum contained hyaluronic acid and protein. Among all the male germ cell stages, only matured sperms showed sialoglycoprotein in their heads and glycogen in the tails. The seasonal variations in the mucosubstances showed that the synthesis of the mucosubstances in the male germ cells of the ovotestis was initiated at the end of the breeding season and attained a maximum in the post-breeding season. Most strikingly the presence of the sperm in the follicular cavity was a permanent feature throughout the seasonal breeding-aestivation cycle of the snails. The synthesis of the mucosubstances in the ovum and the nurse cells was initiated somewhat earlier in the post-breeding season and attained a peak prior to the active breeding season. The importance of the mucosubstances synthesised by the different cells of the ovotestis, is discussed with reference to the reproductive physiology of the snails.

Animals↗

PubMed1992

[Seasonal variation of intraocular pressure after trabeculotomy].

The author reviewed the seasonal variation of intraocular pressure (IOP) in primary open angle glaucoma or late type developmental glaucoma to investigate possible relationships among seasonal variation of IOP, progression of visual field defects and the follow-up period between 53 eyes of 39 subjects with successful trabeculotomy (trabeculotomy group) and 45 eyes of 31 subjects with only medication (no operation group). IOPs in both groups were inclined to be low in summer and high in winter. Maximum seasonal variation of IOP and standard deviation of IOP during all follow-up periods which showed the degree of seasonal variation of IOP had no significant difference between the trabeculotomy group and the no operation group. These results showed that seasonal variation of IOP was not reduced even by successful trabeculotomy. The maximum seasonal variation of IOP and standard deviation of IOP had a tendency to be bigger in cases with progression of visual field defects than in cases with no progression of visual field defects, in both groups. Therefore, seasonal variation of IOP may be an important factor influencing the progression of visual field defects.

Follow-Up Studies↗

PubMed2003

Birth season and environmental influences on patterns of thymic growth in rural Gambian infants.

AIM: In rural Gambia, birth season predicts infection-related adult mortality. Seasonal factors in early life may programme the immune system, possibly via an effect on thymic development. This study tested whether thymus size in rural Gambian infants is affected by birth season, defined as January-June (harvest, few infections) versus July-December (hungry, high infectious load). METHODS: Thymic volume (thymic index) was assessed sonographically at 1, 8, 24 and 52 wk in 138 singleton infants born over 14 consecutive months. Growth and morbidity were regularly assessed. RESULTS: Mean thymic index increased from 19.9 at 1 wk to 30.9 at 8 wk and 35.7 at 24 wk, then fell to 32.0 at 52 wk. Thymic index was associated with each preceding thymic index up to 24 wk. This tracking persisted after correcting for infant weight and month of measurement (p < 0.01). Thymic index at 1 wk was marginally but non-significantly lower in hungry season births (p = 0.06). Thymic index was lower in hungry season measurements; this effect persisted after adjusting for current weight and infection markers, and was strongest at 8 wk (p = 0.001). CONCLUSION: These results describe a pattern of thymic growth followed by diminution in size. An infant's thymic index tracks despite changes in body weight and season. Thymic index was lower in the hungry season. This appears not to be explained by infection or nutritional status. A possible influence of trophic factors in breast milk merits investigation.

Body Weight↗

PubMed2003

Seasonality of births and abortions in New South Wales, Australia.

BACKGROUND: Complex seasonal variations in abortions and seasonal trends have been reported worldwide, but there are no data from Australia. MATERIAL/METHODS: Hospital morbidity and birth data were modelled using time series and regression techniques to describe seasonal changes in births and abortions (1989-99) in NSW, Australia. Data were also analysed to determine demographic predictors of abortions. RESULTS: A higher proportion of births in NSW were recorded in March and September-October. Irrespective of the nuptiality the lowest seasonal indices were recorded in February and November. For married women aged 20-49 years, voluntary abortions were significantly higher in February (t=0.04) and significantly lower in April (t<0.001) and June (t=0.03) and non-voluntary abortions were significantly higher in February (t=0.002) and March (t=0.006). There was seasonality in voluntary abortions (F=4.3, p<0.001) and no seasonality in non-voluntary abortions (F=2.4, p=0.01) for never married women aged 20-49 years. As similar to married women, voluntary abortions among never married women were significantly higher in February (t<0.001) and significantly low in April (t=0.009). The lowest number of abortions were in April. Non-voluntary abortions occurred mostly in March for married women. The average number of voluntary abortions were significantly higher for never married women than for married women. CONCLUSIONS: There was a significant seasonality of births and abortions in NSW, Australia, with a peak of conceptions in December/January. Abortions were lowest in April and non-voluntary abortions were peaked in March. These data suggest that the human reproductive behaviour has a close relationship with environmental factors.

Abortion, Induced↗

PubMed2003

[Influencing factors on the level of the ovulation rate in sheep during the main breeding season--an ultrasonographic study].

The main breeding season for sheep in Germany is from the beginning of September until the end of November. The aim of this study was to determine the factors which influenced the level of the ovulation rate (o. r.) during this period. The examination was conducted over three years and included Booroola. Mutton Merino crosses [heterozygous- (F+) carriers and non-carriers of the Booroola- (FecB) fecundity gene], German Mutton Merino (GMM) and German Blackheaded (GB). In total 1326 examinations were carried out. Between the 8th to 12th day after estrous detection an ovary diagnosis was performed by transrectal scanning with a 7.5 MHz linear probe. The number of the corpora lutea per ewe (o. r.) was documented. The weight and the body condition of the ewes was also determined. During the breeding season the breed of the ewe had the main effect on the level of the o. r. (p < 0.05). This is the reason that the statistical model can only be applied for each breed. The effects of age, year of examination and day of the main breeding season were tested. The age of the ewes and the date of the examination during the breeding season had the main effect on the o. r. In GMM and GB the age influenced the o.r. with an effect of 8.3% and 4.2%. The effect of the season was vice versa (Gmm 3.2%; GB 8.2%). Non-carriers of the Booroola- (FecB) fecundity gene behaved similar like the GMM. However, only the high fecundity carriers of the FecB-gene were strongly influenced by the season. For each breed there exists a typical threshold value for the body weight above which further weight has no effect on the o. r. (GMM 65-70 kg, GB 75-80 kg, non-carriers of the Booroola-FecB gene 55-60 kg and carriers of the FecB-gene 60-65 kg). This value lies at about 80% of the highest measured weight of each breed. The results demonstrated that a balanced age structure in combination with a optimum weight influenced the level of o. r. In addition the date of the season is especially important.

Age Factors↗

PubMed2005

Seasonal variation of lupus nephritis: high prevalence of class V lupus nephritis during the winter and spring.

OBJECTIVE: Systemic lupus erythematosus is a multisystem disease with many clinical variations, including renal involvement. Our aim was to determine whether lupus nephritis (LN) has a specific seasonality. METHODS: Reports of renal biopsies performed from 1990 to 2002 were reviewed. Three hundred and seventy-three patients with class II, III, IV, and V LN were identified. Using the modified WHO classification of LN, diagnoses were tabulated and the seasonality (season of diagnosis) of LN was statistically analyzed. RESULTS: Class IV LN was detected in 179 patients (48%), class II in 63 patients (16.9%), class III in 73 patients (19.57%), and class V in 74 patients (19.9%). No difference could be detected in the number of patients diagnosed in each season when all 373 patients were analyzed as one group. The number of patients with class IV LN was higher during summer and fall than during the winter and spring. In contrast, a higher number of patients with class V LN were observed during the winter and spring seasons than during the summer and fall seasons. The percentage of patients with class V LN was significantly higher during winter and spring than during summer and fall. A similar, though non-significant, trend was seen for class III LN. A striking parallelism was found between the month of occurrence of class III and class V LN. The monthly distribution of the percentage of patients in each month with class III and V LN showed a significant correlation. The monthly distribution of patients with class IV LN was different from those with either class III or V LN. CONCLUSION: We found that the prevalence of class V LN was significantly higher and that of class III LN non-significantly higher in winter and spring. Parallelism between the monthly occurrences of class III and class V may suggest a common trigger. Analysis of the seasonality of LN may contribute to the understanding of the pathogenesis of LN, which may be multifactorial, as the different classes of LN represent different types of glomerular injury. Further studies are needed to clarify this potentially important observation.

Adolescent↗

PubMed2005

Seasonality of births in Croatia.

The aim of this paper was to investigate seasonal fluctuations of the number of births in Croatia. Vital registration data from the years 1970-2002 was used for analysis of the quarterly data (from the years 1970-1997), and monthly data (from the years 1998-2002). Both data sets were smoothed, using seasonal variation removal for quarterly data, and T4253H smoothing for monthly data. Edwards test and Ratchet circular scan tests were used in analysis. The results showed an increase in the summer birth proportion and decrease in the spring birth proportion, distorted during the wartime period (1991-1995). Monthly analysis reveals highest birth proportion in Croatia during July-September period, with peak date moving towards the end of summer, and reaching stability in the beginning of September during the years 2000-2002. This presumes highest conception rate during the beginning of the Christmas holiday season. Secondary peak in January was found in some years, which presumably sets second period of increased conception rate into the Easter holiday season, supporting the observation of the holiday-related birth peaks. Both quarterly and monthly data indicate a birth pattern that does not resemble either "European", or "American" seasonal pattern. Regional analysis showed lack of seasonality in the capital city of Zagreb and either intermittent or stable seasonality pattern in the rest of the country.

Adult↗

PubMed2006

Phoenix sylvestris Roxb pollen allergy: a 2-year randomized controlled trial and follow-up study of immunotherapy in patients with seasonal allergy in an agricultural area of West Bengal, India.

BACKGROUND: Although the efficacy of allergen immunotherapy has been demonstrated in seasonal pollen allergy, there is no report of a double-blind placebo-controlled trial with standardized pollen extract in seasonal respiratory allergy from India. In the agricultural area of eastern India, Phoenix sylvestris Roxb or date sugar palm is grown or cultivated and seasonal allergic rhinitis is common during the pollen season. OBJECTIVE: The objective of the present study was to observe the clinical and immunological changes during a 2-year double-blind placebo-controlled trial of immunotherapy with standardized P sylvestris pollen extract in respiratory patients sensitive to pollen from this wild date palm. Thirty-five subjects with typical seasonal allergic rhinitis with or without bronchial asthma were selected. A symptom-medication score (based on a questionnaire and diary) was correlated with pollen counts as recorded in a Burkard sampler. Eighteen subjects were randomized to a specific immunotherapy (SIT) group receiving regular injections containing standardized allergen extract and 17 to a placebo control group. Changes in the level of specific immunoglobulin (Ig) E, IgG1, and IgG4 were recorded at 3-month intervals. Measurement of wheal diameter, total IgE level and forced expiratory volume in 1 second (FEV1) were performed before starting and a month after finishing therapy. RESULTS: The SIT group showed decreases of 33.5% and 57% from the baseline symptom-medication scores during the first and second treatment season, respectively. This group showed significant decreases in skin-reactivity to P sylvestris pollen extract and in specific IgE levels, and significant increases in FEV,, specific IgGI (1.95-3.2 times higher) and IgG4 (21.24-30.83 times higher). There were no significant changes in total IgE levels. The control group showed no significant changes for any parameter except the development of new sensitization in 2 cases (to Saccharum officinarum pollen grain and Alternaria species spores). The rate of local adverse reactions was 0.024%. CONCLUSION: After a 2-year study, allergen immunotherapy with standardized P sylvestris pollen extract was found to be effective in seasonal respiratory allergic subjects susceptible to P sylvestris pollen with a narrow range of sensitization.

Adult↗

PubMed1990

Seasonal variation in fertility, fecundity and litter sex ratio in laboratory and wild stocks of house mice (Mus domesticus)

Data compilations were made for three parameters pertaining to reproduction in a domestic strain (14 years) and a wild stock (4 years) of commensal house mice: (a) the percentage of females mated that produced litters; (b) the average number of pups per litter; and (c) the sex ratio of the pups in the litters. Fecundity and fertility varied seasonally in both domestic and wild mice. More females become pregnant and litter sizes were larger in the spring, summer, and fall months than during the winter season. Sex ratios also varied seasonally with more male biased litters produced during the 4 winter months. There appear to be seasonal shifts in productivity for both stocks of mice and these seasonal trends have not been altered by domestication under laboratory conditions. In spite of the fact that house mice are generally opportunistic, it is possible that there has been selection in the mice for shifting rates of production in relation to the best seasons of the year in terms of climate and resource availability. The higher production of males during summer months may be geared toward greater success in dispersal at that season and a higher probability that the males can find a territory and mate successfully in summer rather than winter. These results have potential implications for animal breeders and for those who maintain mouse colonies to produce animals for scientific investigations.

Animal Husbandry↗

PubMed1990

Demographic seasonality and development: the effects of agricultural colonialism in Taiwan, 1906-1942.

Nearly all developed countries have experienced dramatic declines in the seasonality of demographic behavior over the last century. This article examines seasonal behavior in the population of Taiwan between 1906 and 1942, during Japanese colonial rule. First, we analyze seasonal demographic cycles and their ties to the cultural calendar and agriculture. Second, we compare seasonality in two regions (Xinzhu and Tainan) that experienced different agricultural development under the colonial regime. Findings demonstrate that demographic seasonality was less pronounced when urban development and colonial agricultural intensification produced more heterogeneous seasonal patterns of labor. We find that changes in agricultural organization, rather than purely a shift to nonagricultural production, may significantly reduce established seasonal timing of demographic behavior.

Agriculture↗

PubMedDate not supplied

Seasonal variations of arterial blood pressure in normotensive and essential hypertensives.

Marked seasonal variations in environmental fluid losses and arterial blood pressure (BP) have been observed by us. Factors causing these changes in BP have been investigated. Effect of seasonal variation on BP was studied in 15 controls and 15 essential hypertensives. Mean temperature and relative humidity in well defined 5 local seasons was recorded. Monthly observations included the plasma levels and 24 hours urinary excretion of norepinephrine (NE), epinephrine (E), sodium (Na+) and potassium (K+). Average systolic, diastolic and mean BP were higher in winter season in both the groups (P less than 0.01). In hypertensives this variation was observed despite a significant increase in drug consumption during winter season (P less than 0.001). Both the groups revealed higher plasma levels and daily urinary excretion of NE and E during winter months, (P less than 0.05 - less than 0.001). 24 hrs urinary volume, Na+ and K+ were significantly higher in winter season (P less than 0.05 - less than 0.001). These parameters showed a negative correlation with mean ambient temperature. Increased sympathetic nervous activity as documented by increased NE and E in plasma and urinary, and decreased environmental loss of fluids and sodium may be contributory to this rise in blood pressure during winter season.

Adult↗

PubMed1989

Megaloblastic anaemia in Zimbabwe. 1: Seasonal variation.

Two hundred and ten patients who were confirmed to have megaloblastic anemia over a 2-year period were grouped according to the month of diagnosis. A distinct seasonal variation was detectable in the occurrence of megaloblastic anemia with a high prevalence in the wet season and a low prevalence in the dry season. The major factor postulated to be responsible for the seasonal fluctuations of the disorder is the concomitant diminution in the availability of folate-rich green vegetables; and not malaria transmission. As the dry season sets in and progresses, the frequency of megaloblastic anaemia cases increases reaching a peak during the wet season. It is suggested that an adequate supply of green vegetables like lettuce, spinach and cabbage throughout the year might lessen or even eliminate the seasonal variation of megaloblastic anaemia presently observed in this community.

Adolescent↗

PubMed1988

A multicenter, open study of the non-sedating antihistamine, terfenadine (Seldane), in the maintenance therapy of seasonal allergic rhinitis.

A multicenter open study was conducted throughout the 1984 fall pollen season to assess the possible development of tolerance or loss of efficacy to terfenadine in the maintenance therapy of patients with seasonal pollinosis. Patients with proven allergic pollinosis were entered into a 1-week initial treatment period taking terfenadine 60 mg bid and only those who responded to the initial treatment with "moderate" to "complete" relief continued on terfenadine throughout a 4 to 11-week pollen season for evaluation of continued efficacy. A total of 179 patients from five study centers were enrolled in the initial treatment period and 154 (86%) responded to terfenadine with "moderate" to "complete" relief of symptoms. Of these 154 patients who continued terfenadine treatment, approximately 90% of the patients maintained the same degree of relief throughout the pollen season. All symptoms of seasonal pollinosis including nasal congestion improved significantly the first day of treatment. This improvement in symptoms continued during the first week and remained unabated throughout the pollen season. The incidence of adverse events was low with sedation being reported by only 2.8% of patients at some time point during the study. It is concluded that terfenadine is a safe and effective non-sedating antihistamine in the maintenance therapy of seasonal allergic pollinosis and that tolerance is not noted during continued administration.

Adult↗

PubMed1987

Modification of bronchial hyperreactivity during pollen season in children allergic to grass.

Ten children, sensitive to grass pollens with seasonal rhinitis and mild asthma, underwent bronchial challenge with carbachol in the pre-seasonal, seasonal, and post-seasonal period. According to pollen count, we observed significant differences between pre-seasonal, seasonal, and post-seasonal values. Also basal FEV1 values varied in the same fashion. Seven of the ten children also participated in a previous similar study in 1984, at which time they did not demonstrate significant variations to bronchial challenge. We wish to emphasize the importance of pollen concentration in the atmosphere as well as the existence of a threshold value of grass pollen necessary for a significant modification in bronchial reactivity to occur.

Asthma↗

PubMed1995

Melatonin binding sites and their role in seasonal reproduction.

The pineal gland has a major role in the translation of scotophase duration into a hormonal signal by the hormone melatonin. Animals such as sheep, goats and deer use the seasonal variation of this signal to coordinate reproductive behaviour with the environment. Despite intensive research over more than 30 years the site(s) of action of melatonin and the resultant intracellular responses are still not clear. This review discusses recent work that has localized the site of action of melatonin in sheep using administration into the hypothalamus in vivo as well as studies on putative melatonin receptors in the pars tuberalis and brain. There is clear evidence that melatonin acting at the level of the pars tuberalis is involved in the seasonal regulation of prolactin secretion, but the evidence for involvement of the pars tuberalis in seasonal reproduction is not compelling. Localized administration of melatonin to the sheep brain revealed that areas anatomically distinct from the pars tuberalis, the ventromedial and arcuate nuclei, simulated seasonal reproductive changes in rams and ewes. Recent studies on brain melatonin binding sites in our laboratory have shown that an antagonist of tissue transglutaminase, Bacitracin, as well as substrates for the enzyme inhibit binding of melatonin to brain membranes. As a working hypothesis, we propose that pineal melatonin secretion alters seasonal reproduction by interactions with a neural transglutaminase at the synapse of neurones involved in the control of GnRH secretion. Synaptic transglutaminase is implicated in the control of the release of neurotransmitter via the synaptic vesicle associated protein, synapsin 1; activation of transglutaminase results in the covalent modification of synapsin 1 such that vesicles are not released from the cytoskeleton. Seasonal variation in the duration of melatonin secretion may result in similar variations in the duration of suppression and activation of transglutaminase. The resultant changes in transmitter release may then be responsible for the seasonal neuronal plasticity previously observed in GnRH neurones.

Animals↗