Sex differences in seasonal variations in P300

Previous reports of seasonal variations in P300 were based on cross-sectional observations of subjects tested at different times of the year. In this study, we tested three groups of subjects in each of two seasons: winter and spring, spring and summer, and summer and winter. We found winter or spring maxima in auditory and visual P300 and visual slow wave. This pattern of results, with the amplitude of P300 being inversely related to the amount of sunlight in a season, supports the hypothesis that the allocation of processing resources varies across the seasons. Our results also suggest a trend for an increased sensitivity of women, as compared with men, to seasonal influences on P300. Although our findings do not provide strong evidence that P300 varies systematically as a function of season, seasonal factors appear to affect cognitive processing (as indexed by P300) differentially in men and women.     

The seasonal characteristics of the course of abdominal typhus

Seasonal fluctuations were studied in the incidence of characteristic abdominal fever symptoms, such as headache, insomnia, asthenia, skin pallor, roseolous eruptions, protracted fever, drop in blood pressure, relative bradycardia, dicrotia, typhoid tongue, enlargement of the liver and spleen, meteorism, constipation, palpable crepitation in the right iliac region, manifest leucopenia. Some symptoms occurred with almost equal frequency in different seasons of the year. In adults, severity of some typhoid symptoms was the greatest, duration the longest, degree the highest in spring, followed, in decreasing rank order by autumn > summer > winter; in children: spring > summer > autumn > winter.     

Seasonal influence on platelet 5-HT levels in patients with recurrent major depression and schizophrenia

The influence of seasons on platelet serotonin (5-HT) concentration was determined in 88 unipolar depressed and 117 schizophrenic male inpatients, and 90 normal male controls. Platelet 5-HT concentrations showed moderate, but insignificant intragroup seasonal variations in healthy controls and in the groups of depressed (psychotic and nonpsychotic) and schizophrenic (positive and negative) patients. In spring, platelet 5-HT concentrations were higher in schizophrenic patients than in normal controls or in depressed patients, while in other seasons platelet 5-HT concentrations were not significantly different between the groups. Higher platelet 5-HT concentrations were detected in psychotic when compared to nonpsychotic depressed patients in summer, fall, and winter. Increased platelet 5-HT concentrations observed in schizophrenic patients with positive symptoms clearly separated these patients from patients with negative schizophrenia, especially in spring, summer, and fall. Our results indicate the necessity to match patients with regard to the season of the sampling, and to divide depressed and schizophrenic patients into subtypes.     

Changes in Wind Speed and Extremes in Beijing during 1960-2008 Based on Homogenized Observations

Daily observations of wind speed at 12 stations in the Greater Beijing Area during 1960-2008 were homogenized using the Multiple Analysis of Series for Homogenization method. The linear trends in the regional mean annual and seasonal (winter, spring, summer and autumn) wind speed series were -0.26, -0.39, -0.30, -0.12 and -0.22 m s-1 (10 yr)-1, respectively. Winter showed the greatest magnitude in declining wind speed, followed by spring, autumn and summer. The annual and seasonal frequencies of wind speed extremes (days) also decreased, more prominently for winter than for the other seasons. The declining trends in wind speed and extremes were formed mainly by some rapid declines during the 1970s and 1980s. The maximum declining trend in wind speed occurred at Chaoyang (CY), a station within the central business district (CBD) of Beijing with the highest level of urbanization. The declining trends were in general smaller in magnitude away from the city center, except for the winter case in which the maximum declining trend shifted northeastward to rural Miyun (MY). The influence of urbanization on the annual wind speed was estimated to be about -0.05 m s-1 (10 yr)-1 during 1960-2008, accounting for around one fifth of the regional mean declining trend. The annual and seasonal geostrophic wind speeds around Beijing, based on daily mean sea level pressure (MSLP) from the ERA-40 reanalysis dataset, also exhibited decreasing trends, coincident with the results from site observations. A comparative analysis of the MSLP fields between 1966-1975 and 1992-2001 suggested that the influences of both the winter and summer monsoons on Beijing were weaker in the more recent of the two decades. It is suggested that the bulk of wind in Beijing is influenced considerably by urbanization, while changes in strong winds or wind speed extremes are prone to large-scale climate change in the region.     

The open surgical approach to subglottic hemangioma

The monthly distribution of relapses in ulcerative colitis was analysed retrospectively to assess seasonal variation. In 338 patients who were regularly followed up at the colitis clinic, 1013 relapses occurred during the period 1977 to 1988. A peak of relapses occurred in the spring and autumn, with a decrease in the summer; the ratio of the observed to expected number of relapses was 201:255.3 for the summer, 289:252.6 for the autumn, 243:249.8 for the winter, and 280:255.3 for the spring. In contrast, month of diagnosis was evenly distributed without seasonality. The data support the concept that exacerbations in ulcerative colitis are influenced by seasonal factors.     

Seasonal influence on 7,12-dimethylbenz[a]anthracene-induced mammary carcinogenesis in Sprague-Dawley rats under controlled laboratory conditions

There is good evidence in some species, including rats, that circannual rhythms are innate and can occur even under constant environmental conditions. Such circannual rhythms, e.g. in hormone levels and immune system function, may influence tumourigenesis. This prompted us to study 7,12-dimethylbenz[a]anthracene(DMBA)-induced mammary carcinogenesis at different seasons of the year in female Sprague-Dawley rats under constant environmental conditions (photoperiod, temperature, air humidity, food). DMBA was administered orally at a dose of 5 mg per rat at the first day of the experiment and then at weekly intervals up to a total dose of 20 mg per rat. Rats were palpated once weekly for the presence of mammary tumours. After 13 weeks, they were necropsied for examination of the number and size of mammary tumours. Age-matched groups of 36-99 rats were used per experiment. When the experiment was performed twice within 2 years during the same season (spring/summer), tumour incidence (56 and 61%) and tumour burden were almost equal, indicating that data obtained in this way were reproducible. However, the same experiment performed in autumn yielded a significantly lower tumour incidence (34%) and tumour burden. When the experiment was started during winter, tumour incidence was similar to the spring/summer groups, but tumour burden was lower. The data indicate a seasonal variation in the development and growth of DMBA-induced breast cancer in Sprague-Dawley rats. One possible explanation for this phenomenon may be the seasonal variation in pineal melatonin production and immune function previously reported in rodents under constant environmental conditions.     

Seasonal changes in heat balance of dogs acclimatized to outdoor climate

Heat production (M), dry heat loss (R+C), evaporative heat loss (E) and rectal temperature (Tre) were measured in a direct calorimeter in female mongrel dogs acclimatized to outdoor climate at Kanazawa (latitude; 36 degrees 35" N), Japan. M and total dry and evaporative heat losses (HL) were minimum at calorimeter wall temperatures (TW) of 26-29 degrees C in summer and 22-26 degrees C in winter (thermoneutral temperature; TNT). The seasonal shift of the lower critical temperature was confirmed. At TW below TNT, the values of M and HL were significantly higher in summer. At TW above TNT, these values increased. A TNT and above, M and HL were significantly higher in winter. (R+C) decreased linearly with increasing TW in both seasons. AT TW below 26 degrees C, (R+C) were significantly higher in summer. At TW above 26 degrees C, E increased greatly. The values of E were significantly higher in winter at TW 29-32 degrees C. Tre remained nearly constant at TNT and below, and increased at TW above TNT in both seasons. Mean body surface temperature (Tsf) decreased with decreasing TW. Body thermal conductance (K) was minimum at TW below 26 degrees C in summer and at TW below 22 degrees C in winter. At TW above these temperatures, K increased significantly. Whole body insulation (I) was significantly higher in winter, particularly at TW 18 degrees C. These results suggest that the dogs reared outdoors in winter acclimatized to cold in two ways; by increasing the insulating effect of the fur coat and by elevating resting heat production.     

A study of the interactive effects of oral contraceptive use and dietary fat intake on blood pressure, cardiovascular reactivity and glucose tolerance in normotensive women

A morphometrical evaluation was made of the seasonal changes affecting the numbers of lymphocytes in the thymus, spleen and pronephros of wild brown trout, Salmo trutta, while the size of the thymus and the three thymic zones were also determined. Results reveal statistically significant changes throughout the year in the number of lymphocytes in the lymphoid organs studied. The spleen and pronephros have similar annual patterns of lymphocyte distribution with high numbers in two seasons, spring and autumn, and two periods of lymphoid involution in winter and summer. The highest numbers of thymocytes occur in trout caught in May and August, and the lowest in winter. In addition to normal lymphocytes, degenerated lymphoid cells that show pale cytoplasm devoid of cell organelles, also occurred in all the lymphoid organs. A negative correlation exists between the numbers of normal lymphocytes and that of degenerated lymphoid cells. The thymic size, as well as that of the subcapsular, inner and outer thymic zones, undergo very significant changes over the year. We discuss the relevance of cell proliferation, cell migration and in situ cell death for the circannual variations observed in the cell content of trout lymphoid organs, together with the possible causes.     

Effects of mixed rare earth fertilizer on yield and nutrient quality of leafy vegetables during different seasons

Using Chinese cabbage and rape as test material and examining the same soil conditions at different seasons(spring and autumn), the effects of mixed rare earth fertilizer on the yield and nutrient quality of leafy vegetables were studied to provide a theoretical basis for the application of mixed rare earth fertilizer in agriculture. Results showed a seasonal difference in the nutrient quality of Chinese cabbage and rape. For crops planted in autumn, the soluble sugar and vitamin C content were higher, the titratable acid and nitrate content were lower, and the sugar acid ratio was higher relative to crops planted in spring. Mixed rare earth treatments promoted growth of both crops during both seasons. The plot yield, stem and leaf fresh and dry matter weight, and dry and fresh ratio increased. These increases for Chinese cabbage were greater in autumn than in spring while for rape, the increases were greater in spring than autumn. The soluble sugar content, titratable acid content and sugar acid ratio were increased and the nitrate content decreased, in autumn the effects were more obvious than in spring. In spring, the vitamin C content was increased, and the increase was greater for Chinese cabbage than rape. In autumn, the vitamin C content decreased, and the decrease was greater for rape than Chinese cabbage. At the same time, the content of heavy metals such as Cu, Zn, Cd, Pb and Ni in stems and leaves decreased. This decrease was greater in spring for Chinese cabbage and in autumn for rape.     

Effect of adjacency on the distribution of new stutterings in two successive readings

The postcoital antifertility properties of benzene hot extracts of Hibiscus rosa sinensis flowers, leaves, and stembarks, collected during the winter, spring, rainy, and summer seasons, were investigated in female rats. Only extracts from the flowers of the plant were 100% effective in preventing pregnancy. Those flowers collected during the winter showed the greatest potency, followed by those collected in the spring, rainy season, and summer, in decreasing order. Benzene extracts of flowers collected from Hibiscus mutabilis, Hibiscus schizopetalus, and Malvasicus grandiflorus, plants resembling Hibiscus rosa sinensis in petaloid structure, did not markedly affect pregnancy.     

Changes in Seasonal Cycle and Extremes in China during the Period 1960-2008

Recent trends in seasonal cycles in China are analyzed, based on a homogenized dataset of daily temperatures at 541 stations during the period 1960-2008. Several indices are defined for describing the key features of a seasonal cycle, including local winter/summer (LW/LS) periods and local spring/autumn phase (LSP/LAP). The Ensemble Empirical Mode Decomposition method is applied to determine the indices for each year. The LW period was found to have shortened by 2-6 d (10 yr)-1, mainly due to an earlier end to winter conditions, with the LW mean temperature having increased by 0.2℃-0.4℃ (10 yr)-1, over almost all of China. Records of the most severe climate extremes changed less than more typical winter conditions did. The LS period was found to have lengthened by 2-4 d (10 yr)-1, due to progressively earlier onsets and delayed end dates of the locally defined hot period. The LS mean temperature increased by 0.1℃-0.2℃ (10 yr)-1 in most of China, except for a region in southern China centered on the mid-lower reaches of the Yangtze River. In contrast to the winter cases, the warming trend in summer was more prominent in the most extreme records than in those of more typical summer conditions. The LSP was found to have advanced significantly by about 2 d (10 yr)-1 in most of China. Changes in the autumn phase were less prominent. Relatively rapid changes happened in the 1980s for most of the regional mean indices dealing with winter and in the 1990s for those dealing with summer.     

Seasonal variation in molluscicidal activity of Solanum nigrum L

Solanum nigrum L. leaves and fruits were shown to have molluscicidal activities against snails transmitting schistosomiasis and fascioliasis. In the present study, their molluscicidal activity against adult Biomphalaria alexandrina snails was assessed to determine whether plants collected at various seasons would have different degrees of toxicity. Leaves and fruits of three S. nigrum varieties were collected from Faiyoum and/or Giza during the four seasons. Leaves collected in autumn had the highest effect (LC50-35.4) followed by spring (LC50 = 44.36), summer (LC50 = 46.7) and winter (LC50 = 100.4). Toxicity of plant extracts was also affected by other seasonal dependent factors. These are the duration of plant exposure to direct sunlight and the size of the fruits. S. nigrum (black fruits) was more toxic (LC50 = 18.1) than the other two types, S. nigrum v. vellosum (yellow fruits) (LC50 = 38.9) and S. nigrum v. juidaicum (red fruits) (LC50 = 34.7).     

Growth, voluntary food intake and digestion in farmed temperate and tropical deer

Growth and voluntary feed intake (VFI) in grazing temperate farmed deer species are influenced by the feeding value of the forage and the stage of the deer's seasonal cycle. Liveweight gain (LWG) of growing red deer was greater when perennial ryegrass (0.80)/white clover (0.20) pasture was grazed at 10 cm than 5 cm surface height, but venison production by one year of age was still low. Chicory and red clover were of superior feeding value for deer than perennial ryegrass-based pastures, increasing LWG of young red and hybrid (0.25 elk; 0.75 red deer) deer during summer and autumn, due to higher VFI and to higher organic matter digestibility. Relative to perennial ryegrass, chicory disintegrated faster in the rumen, with very low rumination time and faster rumen outflow rates of liquid and particulate matter. Inputs of red clover and chicory substantially increased venison carcass weights at one year of age from grazing red and hybrid stags. In indoor pen feeding studies, red deer were shown to have a seasonal cycle of digestive function, with greater rumen mean retention time (MRT) and greater rates of rumen ammonia production in summer than in winter. It was deduced that the purpose of the digestive cycle was to maintain apparent digestibility constant as VFI increased during summer. Tropical sambar deer were also shown to have seasonal cycles in growth and VFI that were of reduced amplitude compared with red deer. Peak VFI and growth occurred in autumn and minimum VFI and growth occurred in spring. Feed conversion (kg DM eaten/kg LWG) was more efficient for sambar than for red deer, due to lower VFI and lower heat production, but there was no difference between species in digestive efficiency.     

Stratum corneum lipids: the effect of ageing and the seasons

Stratum corneum lipids play a predominant role in maintaining the water barrier of the skin. In order to understand the biological variation in the levels and composition of ceramides, ceramide 1 subtypes, cholesterol and fatty acids, stratum corneum lipids collected from tape strippings from three body sites (face, hand, leg) of female Caucasians of different age groups were analysed. In addition, we studied the influence of seasonal variation on the lipid composition of stratum corneum from the same body sites. The main lipid species were quantified using high-performance thin-layer chromatography and individual fatty acids using gas chromatography. Our findings demonstrated significantly decreased levels of all major lipid species, in particular ceramides, with increasing age. Similarly, the stratum corneum lipid levels of all the body sites examined were dramatically depleted in winter compared with spring and summer. The relative levels of ceramide 1 linoleate were also depleted in winter and in aged skin whereas ceramide 1 oleate levels increased. The other fatty acid levels remained fairly constant with both season and age, apart from lignoceric and heptadecanoic acid which showed a decrease in winter compared with summer. The decrease in the mass levels of intercellular lipids and the altered ratios of fatty acids esterified to ceramide 1, are likely to contribute to the increased susceptibility of aged skin to perturbation of barrier function and xerosis, particularly during the winter months.     

Seasonal effects on human physiological adaptation factors, thermotolerance and plasma fibronectin

Plasma fibronectin (PF) influences shock survival and basal levels increase with active conditioning that improves human physiological adaptation factors (PAF) and thermotolerance (TT). To evaluate further PF's relationship with PAF and TT, the effects of passive conditioning with seasonal change (spring vs. summer) in New England on PAF, TT, basal PF level and PF level during hot-humid exercise (HHE; bicycling; 40 +/- 4% VO2max; 35 degrees C; 70% rh; 45 min) were examined in male subjects (28.2 +/- 1.6 years; N = 7; values are means +/- SE). The spring and summer studies were separated by 2 months. In addition, 2 months prior to the spring study, a winter basal PF pre-screening was conducted. Winter (287 +/- 36 micrograms/ml), spring (272 +/- 21 micrograms/ml), and summer (278 +/- 19 micrograms/ml) basal PF levels were similar. The PF response during HHE was unremarkable with seasonal change. PAF were improved, since blood volume (6266 +/- 276 vs. 5895 +/- 251 ml), plasma volume (3896 +/- 198 vs. 3601 +/- 165 ml) and HHE sweat rate (18.7 +/- 5.5 vs. 12.9 +/- 6.4 ml/min) were elevated (p < 0.05) in the summer compared to the spring. However, this was not accompanied by improved TT, since spring and summer rectal temperatures during HHE were similar, while summer heart rate was elevated (p < 0.05) compared to the spring. In contrast to active conditioning, passively-induced improvements in PAF were not associated with elevations in TT or PF level. Unlike PAF, PF elevations might only occur when the conditioning resulted in increased TT, which suggests a potential for PF as a TT marker.     

Characteristics of UVA-induced delayed tanning: seasonal variation

We studied seasonal variation in UVA-induced delayed tanning and compared it to that in UVA + B-induced delayed tanning. The minimal tanning dose (MTD) and the minimal melanogenic dose (MMD) were determined one week after UVA exposure or UVA + B exposure, respectively. The MTD determined in the summer (June to August) was significantly higher than that in winter (December to February). In addition, while MTD in the winter correlated well with skin color, there was no correlation between MTD and skin color in summer. MTD tended to correlate with self-reported tanning history at the initiation of tanning in the winter, but they were not correlated with each other in the summer. The MMD measured in the summer was significantly lower than that in the winter. MMD correlated well with skin color in both seasons; the lighter the skin, the smaller the MMD. Also, a correlation was detected between MMD and self-reported tanning history. These results suggest that the susceptibilities of delayed tanning to UVA and UVA + B are affected by different factors.     

Seasonal fluctuations in the secretory response of neuroendocrine cells of Aplysia californica to inhibitors of protein kinase A and protein kinase C

The neuroendocrine bag cells of Aplysia provide an excellent model system for exploring the roles of second-messenger pathways regulating peptide hormone secretion. Both the cAMP and diacylglycerol second-messenger systems and their associated protein kinases (PKA and PKC) are involved in regulating membrane excitability in bag-cell neurons of Aplysia. The purpose of the present set of experiments was to determine if PKA and PKC also play roles in regulating egg laying hormone (ELH) secretion from bag-cell neurons. Abdominal ganglia with attached bag-cell clusters and connective nerves were dissected from reproductively mature Aplysia, and ELH secretion in response to electrically stimulated afterdischarges was measured by RIA. ELH secretion from bag cells treated with protein-kinase inhibitors (Rp-cAMPS to inhibit PKA; H-7 to inhibit PKC) was compared to that from untreated controls. Our experiments showed that 100 microM Rp-cAMPS significantly attenuated ELH secretion during the nonbreeding seasons (winter and spring) of 2 consecutive years. This suggested a role for PKA in regulating ELH secretion. However, Rp-cAMPS had no effect on ELH secretion during the breeding seasons (summer and fall) of 2 consecutive years, even when the dose of Rp-cAMPS was increased to 200 microM. These findings indicate that there is a seasonal fluctuation in responsiveness to PKA inhibition. We also investigated if there was a seasonal fluctuation in the ability of the PKC inhibitor H-7 to suppress ELH secretion. During the nonbreeding season, 10-100 microM H-7 significantly inhibited ELH secretion, but during the breeding season, only the highest dose (100 microM) of H-7 inhibited ELH release. These results confirm that PKC plays a role in regulating ELH secretion and indicate that there is a seasonal fluctuation in responsiveness to PKC inhibition. Overall, our findings suggest that both the cAMP and diacylglycerol second-messenger pathways are regulated on a seasonal basis.     

The impact of cognitively impaired patients and shift on nursing assistant stress

Sixty-four male Wistar rats (mean weight 215 +/- g) were divided into two groups of 32 animals each, with four additional subgroups (n = 8). The experimental group was subjected to immobilization stress for 24 hours and sacrificed during the photo - (10:00-14:00 hours) and scotophases (00:00-02:00 hours) of spring and winter. Photophase and seasonal differences were observed (p < 0.0001) between the corticomedullary karyometric values obtained in the control group. Similar results were obtained in the experimental group, though the seasonal differences were greater and favored spring (p < 0.0001), while the photophase differences were less important (p < 0.03). The number of synaptic ribbons showed a significant inversion of the physiological day/night ratio in both seasons. Similar results were obtained for the melatonin serum levels. The results suggest that photophase and season may be conditioning factors in the albino rat regarding pineal response to stress immobilization.     

Acute gouty arthritis is seasonal

OBJECTIVE: Information regarding effect of weather conditions on gout is sparse. We conducted a study in the USA to examine whether gout is seasonal. METHODS: We reviewed synovial fluid (SF) analyses from our laboratory during 1990-1995 and identified 359 patients who had acute gouty attacks. All fluids of patients with acute gout had intracellular monosodium urate crystals and SF leukocyte counts > 2000/mm3 or more than 10 leukocytes per high power field (HPF). Retrospective chart review of all patients was performed to confirm a clinical picture of acute gout. A control group included 76 patients with acute pseudogout whose SF were analyzed during the same period and who had intracellular calcium pyrophosphate crystals and inflammatory leukocyte counts as in patients with gout. RESULTS: Acute gout was most common during the spring; n = 115 (32%). Ninety (25%) patients had acute gout attacks in the fall; 81 (23%) had acute attacks during the summer; 73 (20%) had acute attacks in the winter. One-way analysis of variance (ANOVA) was used to compare the overall frequency of acute gout during the months and seasons. Using ANOVA, there was no overall statistically significant difference in the incidence of gout per season (p = 0.07), although it approached statistical significance. Acute gouty attacks were more common in the spring compared with winter (p = 0.002) and summer (p = 0.015). There was a trend but no statistically significant difference compared with fall. Winter was the season in which the fewest acute gouty cases were seen, although it was not statistically significant. No seasonal difference was seen in the pseudogout group. There was no correlation between either mean monthly temperature or humidity and the incidence of acute gouty attacks. CONCLUSION: Acute gout attacks are significantly more common in the spring. No seasonal variation was seen in patients with acute pseudogout attacks.