Seasonal Variation In Effects Research Articles

Seasonal variation in the effect of antihypertensive treatment with the irbesartan/hydrochlorothiazide combination.

There is increasing awareness of seasonal variation in blood pressure (BP). In the present analysis, we investigated seasonal variation in the antihypertensive treatment effect of the irbesartan/hydrochlorothiazide combination in patients with stage 2 and 3 hypertension. The study participants were hypertensive patients enrolled in a 12-week therapeutic study. Antihypertensive treatment was initiated with irbesartan/hydrochlorothiazide 150/12.5 mg/day, with possible uptitration to 300/12.5 mg/day and 300/25 mg/day at 4 and 8 weeks of follow-up, respectively. The month of treatment commencement was classified as spring/summer (May to August) and autumn/winter (September to December). Of the 501 enrolled patients, 313 and 188 commenced antihypertensive treatment in spring/summer and autumn/winter, respectively. The mean changes in systolic/diastolic BP at 8 and 12 weeks of follow-up were greater in patients who commenced treatment in autumn/winter (-32.3/-16.5 and -34.2/-16.7 mmHg, respectively) than those who commenced treatment in spring/summer (-28.4/-13.9 and -27.1/-12.8 mmHg, respectively), with a between-season difference of 3.9 (95% confidence interval [CI], 1.4-6.4, P = 0.002)/2.6 (95% CI, 0.9-4.2, P = 0.002) mmHg and 7.0 (95% CI, 4.7-9.3, P < 0.0001)/3.9 (95% CI, 2.4-5.4, P < 0.0001) mmHg, respectively. Further subgroup analyses according to several baseline characteristics showed a greater between-season difference in the changes in systolic BP in patients aged ≥55 years than in those <55 years (n = 255, 12.6 mmHg vs. n = 246, 6.9 mmHg, P = 0.02), especially in patients who did not use antihypertensive medication at baseline (n = 94, 15.4 mmHg vs. n = 132, 5.4 mmHg, P = 0.006). In conclusion, there is indeed seasonality in the antihypertensive treatment effect, with a greater BP reduction in patients who commenced treatment in cold than warm seasons.

Seasonal variation in effect of anti-PD-1 initiation on overall survival among patients with advanced melanoma.

Melanoma is a highly immunogenic cancer, and circannual rhythms influence the activity of the immune system. We retrospectively collected information on all cases with metastatic melanoma (ocular melanoma excluded) that initiated treatment with BRAF-inhibitor-based therapy (BRAFi) or anti-PD-1 monotherapy (PD-1). Cases were divided in two groups based on treatment initiation in the summer half-year (April to September) or winter half-year (October to March). We collected a total of 1054 (BRAF-i) and 1205 (PD-1) patient cases. Median follow-up was 39.7 (BRAFi) and 47.5 (PD-1) months. We did not observe differences in outcomes across patients who were treated in summer versus winter in the BRAFi cohort. Furthermore, we did not observe significant differences in ORR, CRR, and PFS in the PD-1 cohort. However, in patients with BRAF wild-type disease of the PD-1 cohort, treatment initiation in summer was associated with an improved OS (mOS 39.7 months [summer] versus 21.3 months [winter]; HR 0.70, 95% CI 0.57-0.86, p=.0007). This result remained robust to multivariable proportional hazards adjustment (HR 0.70, 95% CI 0.57-0.87, p=.001). Initiation of immunotherapy in summer is associated with prolonged survival in patients with BRAF wild-type melanoma living in Denmark.

Correlation between the seasonal variations in phlorotannin content and the antiallergic effects of the brown alga Ecklonia cava subsp. stolonifera

Here, we investigated the antiallergic effects of brown algae (Ecklonia cava subsp. stolonifera) harvested on the coast of Nishinoshima Town, Oki Islands, Shimane Prefecture, Japan. Specifically, we investigated whether the active components of E. cava ssp. stolonifera vary seasonally and whether such variation correlates with seasonal variation in the antiallergic effects of the algae. High-performance liquid chromatography, liquid chromatography–mass spectrometry, and nuclear magnetic resonance spectra were used to analyze 80% methanol (80M) extract from E. cava ssp. stolonifera and to isolate eckol, 6,6′-bieckol, 8,8′-bieckol, dieckol, and phlorofucofuroeckol-A as the major active compounds in the species' phlorotannins. Monthly measurements of phlorotannin content and the isolated phlorotannins in the 80M extract showed that the crude phlorotannin and isolated phlorotannin content was higher in the summer–autumn period than in the winter–spring period. The antiallergic effects of the monthly 80M extracts and the isolated phlorotannins were confirmed by measuring inhibition of inflammation-related enzymatic activity, suppression of degranulation in rat basophile leukemia-2H3 cells, and effects on allergic inflammation in Institute of Cancer Research strain mice. There was partial seasonal variation in the effect of 80M extract in combination with the amount of isolated phlorotannin and the antiallergic effects. When phlorotannin was removed from the extracts using polyvinylpolypyrrolidone, the antiallergic effects were no longer observed; thus, phlorotannins are the active components. Overall, these results show that correlations exist between the seasonal variations in the suppressive effect of 80M extract on enzymatic activities, allergic inflammation in mice, and the amount of isolated phlorotannins.

Seasonal variation in effects of urea and phosphorus on phytoplankton abundance and community composition in a hypereutrophic hardwater lake

Abstract Urea accounts for half of global agricultural fertiliser applications, yet little is known of its role in eutrophication of freshwater ecosystems, nor how it interacts with phosphorus (P) in regulating phytoplankton composition, especially during spring and autumn. To identify when and how urea and P inputs interact across the ice‐free period, we conducted seven monthly fertilisation experiments in 3,240‐L mesocosms from ice‐off to ice‐formation in a hypereutrophic lake. In addition, we ran bioassays with ammonium (NH4+) to compare the effects of urea with those of NH4+, the immediate product of chemical decomposition of urea. Analysis of water‐column chlorophyll a and biomarker pigments by high‐performance liquid chromatography revealed that addition of inorganic P alone (100 µg P L–1 week–1) had no significant impact on either algal abundance or community composition in hypereutrophic Wascana Lake. Instead, fertilisation with urea (4 mg N L−1 week–1) alone, or in concert with P, significantly (p &lt; 0.05) increased algal abundance in spring and much of summer, but not prior to ice formation in October. In particular, urea amendment enhanced abundance of cryptophytes, chlorophytes, and non‐diazotrophic cyanobacteria during April and May, while fertilisation in summer and early autumn (September) increased only chlorophytes and non‐diazotrophic cyanobacteria. Comparison of urea mesocosms with NH4+ bioassays demonstrated that urea lacked the inherent toxicity of NH4+ in cool waters, but that both compounds stimulated production during summer experiments. This study showed that urea pollution can degrade water quality in P‐rich lakes across a variety of seasonal conditions, including spring, and underscores the importance of quantifying the timing and form of N inputs when managing P‐rich freshwaters.

Seasonal variation in patch and landscape effects on forest bird communities in a lowland fragmented landscape

In fragmented temperate landscapes, species responses to patch and landscape structures are likely to vary across seasons. However, few studies have examined the dynamic effects on biodiversity across seasons. We examined the effects of patch attributes and connectivity and seasonal variation in the effects of these environmental variables on forest bird communities at woodland fragments surrounded by agricultural land across three seasons (breeding, dispersal, and wintering seasons). We surveyed birds in woodland remnants and examined the effects of patch area, woodland connectivity, woodland type, and three interaction terms between these environmental variables and season (patch area × season, connectivity × season, and woodland type × season) on forest bird communities. In the results, species richness, abundance and composition of forest bird communities were associated with patch attributes and connectivity, and some of these associations varied depending on the season. Specifically, there were significantly higher abundances of specialist birds in riparian woodlands compared to conifer woodlands during the breeding season, whereas this pattern was reversed during the winter. In addition, we found the negative effects of patch area during the dispersal and wintering seasons and the positive effect of connectivity during the dispersal season on generalist bird abundances. These results suggest that woodland patches with high conservation values differ among three seasons. The conservation planning for a fragmented landscape therefore needs to consider the role of patch attributes and connectivity during multiple seasons rather than just the breeding season.

Seasonal variation in effects of herbivory on foliar nitrogen of a threatened conifer.

Invasive herbivores can dramatically impact the nitrogen (N) economy of native hosts. In deciduous species, most N is stored in stem tissues, while in evergreen conifer species N is stored in needles, making them potentially more vulnerable to herbivory. In eastern forests of the USA, the long-lived, foundational conifer eastern hemlock (Tsuga canadensis) is under the threat of extirpation by the invasive hemlock woolly adelgid (HWA: Adelges tsugae). We assessed the impact of HWA infestation on the patterns of seasonal foliar N availability in hemlock planted in a deciduous forest understory. Over the course of a year, we sampled needles and twigs and measured N, carbon (C), C:N ratio, and total protein concentrations. Tissue sampling events were timed to coincide with key life-history transitions for HWA to determine the association between HWA development and feeding with these foliar nutrients. In uninfested trees, needle and twig N concentrations fluctuated across seasons, indicating the potential importance of N storage and remobilization for the N economy of eastern hemlock. Although N levels in HWA-infested trees also cycled annually, the degree to which N concentrations fluctuated seasonally in tissues was significantly affected by HWA feeding. These fluctuations exceeded N levels observed in control trees and coincided with HWA feeding. HWA feeding generally increased N concentrations but did not affect protein levels, suggesting that changes in N do not occur via adelgid-induced protein breakdown. Herbivore-induced mobilization of N to feeding sites and its rapid depletion may be a significant contributor to eastern hemlock mortality in US forests.

Seasonal variation in effects of multiple predators on an intertidal mussel bed: implications for interpretation of manipulative experiments

Seasonal variation in effects of multiple predators on an intertidal mussel bed: implications for interpretation of manipulative experiments

Seasonal variation in effect of spa therapy on chronic pain

This study sought to investigate whether the effects of spa therapy are subject to seasonal variation as suggested by conventional spa therapy research. A total of 268 female (age 31–90 yr) and 119 male (age 35–85 yr) patients with noninflammatory chronic pain were studied. Patients stayed at an Austrian spa for 3 wk and received 2–4 treatments per day, including mudpacks, massages, and exercise therapy. In different groups of patients for 2 yr, pain (self-assessed by questionnaire and Likert scales) and associated variables (mood, fatigue) were measured at the beginning, end, and 6 wk after spa therapy. Data were analyzed by multivariate analysis of covariance controlling for possible group differences between seasons and cosinor analysis. The effect of spa therapy on pain was seasonally dependent; short-term decrease of pain was best between April and June and medium-term decrease of pain was best between October and November, with a second minor peak in fall and spring, respectively. The magnitude of the seasonal variation was greater for back (∼30%) than for joint (∼20%) pain. Positive mood also improved most between April and June. The observed semi-annual variations of pain do not correspond to the well-known annual change in many physiological and psychological variables. The results suggest that the effects of spa therapy and possibly other related treatments, such as physical and alternative therapies, are subject to seasonal variation.