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PubMed2006

Accounting for seasonal patterns in syndromic surveillance data for outbreak detection.

BACKGROUND: Syndromic surveillance (SS) can potentially contribute to outbreak detection capability by providing timely, novel data sources. One SS challenge is that some syndrome counts vary with season in a manner that is not identical from year to year. Our goal is to evaluate the impact of inconsistent seasonal effects on performance assessments (false and true positive rates) in the context of detecting anomalous counts in data that exhibit seasonal variation. METHODS: To evaluate the impact of inconsistent seasonal effects, we injected synthetic outbreaks into real data and into data simulated from each of two models fit to the same real data. Using real respiratory syndrome counts collected in an emergency department from 2/1/94-5/31/03, we varied the length of training data from one to eight years, applied a sequential test to the forecast errors arising from each of eight forecasting methods, and evaluated their detection probabilities (DP) on the basis of 1000 injected synthetic outbreaks. We did the same for each of two corresponding simulated data sets. The less realistic, nonhierarchical model's simulated data set assumed that "one season fits all," meaning that each year's seasonal peak has the same onset, duration, and magnitude. The more realistic simulated data set used a hierarchical model to capture violation of the "one season fits all" assumption. RESULTS: This experiment demonstrated optimistic bias in DP estimates for some of the methods when data simulated from the nonhierarchical model was used for DP estimation, thus suggesting that at least for some real data sets and methods, it is not adequate to assume that "one season fits all." CONCLUSION: For the data we analyze, the "one season fits all " assumption is violated, and DP performance claims based on simulated data that assume "one season fits all," for the forecast methods considered, except for moving average methods, tend to be optimistic. Moving average methods based on relatively short amounts of training data are competitive on all three data sets, but are particularly competitive on the real data and on data from the hierarchical model, which are the two data sets that violate the "one season fits all" assumption.

Computer Simulation↗

PubMed2026

Rumen DNA virome plasticity and viral metabolic potential are associated with seasonal adaptation in grazing yak and cattle on the Qinghai-Tibet Plateau.

BACKGROUND: As a diverse and abundant component of the rumen ecosystem, viruses interact with other microorganisms and are thought to influence microbial metabolism and host productivity. However, how the rumen virome responds to seasonal fluctuations in extreme environments remains poorly understood. Here, metagenomic analyses were used to investigate temporal dynamics of viral diversity, functional potential, and virus-host associations in the rumen virome of yak and cattle on the Qinghai-Tibet Plateau across warm and cold seasons. RESULTS: Rumen viral communities exhibited pronounced seasonal variation in both yaks and cattle, with higher alpha diversity observed during the cold season than in the warm season. Across seasons, the yak rumen virome showed greater alpha diversity and community stability than that of cattle. In total, 27,353 temperate and 31,976 virulent viral operational taxonomic units (vOTUs) were identified, predominantly belonging to the class Caudoviricetes. These viruses were linked to microbial hosts spanning 24 bacterial and 8 archaeal phyla, with Bacteroidota and Bacillota representing the dominant lineages. Virus-host associations were more numerous in the cold season and showed distinct host-specific patterns between yaks and cattle. Cold-season virome exhibited reduced diversity of anti-defense genes and enrichment of auxiliary metabolic genes (AMGs) associated with fatty acid metabolism and hemicellulose degradation. Notably, greater divergence between yaks and cattle was observed during the cold season: the yak rumen virome was enriched in pathways related to amino acid, lipid, and energy metabolism, as well as cellulose-degrading CAZyme families, whereas the cattle rumen virome showed enrichment in general carbohydrate metabolism and replication and repair processes. CONCLUSION: Seasonal plasticity of rumen DNA virome and pronounced interspecific divergence between yaks and cattle provide insight into their distinct microbial processes in the harsh environment of the Qinghai-Tibet Plateau. These findings suggest that the rumen DNA virome exhibits complex ecological and functional responses to seasonal variation and may be associated with host-microbiome interactions and nutrient utilization under environmental stress. This study highlights the ecological relevance of rumen viral genomes in understanding virus-microbiome interactions, microbial adaptation, and nutrient utilization in high-altitude ruminants.

Auxiliary metabolic genes↗

PubMed2002

Modifications of airway responsiveness to adenosine 5'-monophosphate and exhaled nitric oxide concentrations after the pollen season in subjects with pollen-induced rhinitis.

STUDY OBJECTIVE: s: To determine the effect of cessation of exposure to pollen on airway responsiveness to adenosine 5'-monophosphate (AMP) in subjects with pollen-induced rhinitis, and to explore the relationship between changes in airway responsiveness and changes in exhaled nitric oxide (ENO) levels. STUDY DESIGN: Subjects were studied during the pollen season and out of season. SETTING: Specialist allergy unit in a university hospital. PATIENTS: Fourteen subjects without asthma with pollen-induced rhinitis who showed bronchoconstriction in response to methacholine and AMP during the pollen season and 10 healthy nonatopic control subjects. MEASUREMENTS AND RESULTS: In subjects with pollen-induced rhinitis, ENO concentrations, provocative concentration of agonist causing a 20% fall in FEV(1) (PC(20)) methacholine, and PC(20) AMP were determined during the pollen season and out of season. Healthy control subjects were studied during the pollen season. In subjects with allergic rhinitis, PC(20) AMP increased from a geometric mean of 79.4 mg/mL (95% confidence interval [CI], 31.6 to 199.5 mg/mL) during the pollen season to 316.2 mg/mL (95% CI, 158.5 to 400.0 mg/mL) out of season (p = 0.004). The ENO concentrations decreased from 63.1 parts per billion (ppb) [95% CI, 50.1 to 79.4 ppb] during the pollen season to 30.2 ppb (95% CI, 23.4 to 38.0 ppb) out of season (p < 0.001). The ENO concentrations out of pollen season were still significantly increased in subjects with pollen-induced rhinitis when compared with healthy control subjects. There was no relationship between individual changes in ENO levels and changes in either PC(20) methacholine or PC(20) AMP. CONCLUSIONS: In pollen-sensitive subjects with allergic rhinitis, the cessation of exposure to pollen is associated with a significant reduction of airway responsiveness to inhaled AMP. However, no association was found between allergen-induced changes in ENO values and in airway responsiveness to either direct or indirect bronchoconstrictors. These findings suggest that modifications in ENO and in airway responsiveness are the consequence of different alterations induced by allergen exposure on the lower airways.

Adenosine Monophosphate↗

PubMed1994

Effect of nutrition on seasonal patterns of LH, FSH and testosterone concentration, testicular mass, sebaceous gland volume and odour in Australian Cashmere goats.

The effects of season and diet on LH, FSH and testosterone concentrations, testicular mass, sebaceous gland volume and male odour were examined in mature Australian cashmere goat bucks fed ad libitum with diets of low or high quality for 16 months under natural photoperiod at 29 degrees S, 153 degrees E (n = 6 per treatment). Each week plasma was sampled, the bucks were weighed, scored for male odour and assessed for testicular mass based on scrotal circumference. Each month a skin sample was taken from the occipital region for histological assessment of sebaceous gland volume. For each variable there was a clear circannual cycle that was significantly influenced by dietary treatment. In bucks fed the low-quality diet, the timing of seasonal changes in LH and testosterone concentration, sebaceous gland volume and odour score was similar, with a mid-autumn peak. In each case the high-quality diet advanced, extended the duration and increased the magnitude of the seasonal increase. FSH concentrations peaked in late spring (in bucks on the high-quality diet) or summer (in bucks on the low-quality diet), reaching a nadir in early winter. The high-quality diet significantly increased concentrations only in the last 2 months of the experiment (spring). There was no overall association between these variables and change in testicular mass; instead, it was strongly correlated with voluntary feed intake and change in body mass, themselves subject to seasonal variation with a winter or spring peak. The high-quality diet induced large increases in body mass and testicular mass during the first months of the experiment without influencing the seasonally low concentrations of FSH, LH and testosterone present at the time. These results demonstrate that the male, like the female, Australian cashmere goat, exhibits marked reproductive seasonality, and that nutrition is a powerful modulator of the seasonal cycle. They suggest that testosterone concentration, sebaceous gland volume and odour score are ultimately dependent upon LH secretion, which appears to be under strong seasonal (photoperiodic) control, with the effects of enhanced nutrition limited to periods when photoperiodic inhibition is waning. However, seasonal regulation of testicular mass, and therefore sperm production, appears to be primarily dependent on changes in voluntary feed intake and growth, with the seasonal cycle of testicular mass more a consequence of the seasonal appetite or growth cycle than of changing gonadotrophin concentrations.

Animal Nutritional Physiological Phenomena↗

PubMed1999

Seasonal changes in the negative feedback regulation of the secretion of the gonadotrophins by testosterone and inhibin in rams.

Three experiments were conducted with castrated Romney Marsh rams (wethers) to investigate the ability of testosterone and inhibin to suppress the secretion of LH and FSH during the breeding and the non-breeding seasons. In Experiment 1, wethers (n=5/group) were treated every 12 h for 7 days with oil or 16 mg testosterone propionate (i.m.) and were then given two i.v. injections either of vehicle or of 0.64 microg/kg human recombinant inhibin A (hr-inhibin) 6 h apart. Blood samples were collected for 4 h before inhibin or vehicle treatment and for 6 h afterwards for the assay of LH and FSH. In Experiments 2 and 3 wethers underwent hypothalamo-pituitary disconnection (HPD) and were given 125 ng GnRH i.v. every 2 h. In Experiment 2, HPD wethers (n=3/group) were injected (i.m.) every 12 h with oil or testosterone and blood samples were collected over 9 h before treatment and 7 days after treatment. In Experiment 3, HPD (n=5/group) wethers were treated with vehicle or hr-inhibin, as in Experiment 1, after treatment with oil, or 4, 8 or 16 mg testosterone twice daily for 7 days. Blood samples were collected over 4 h before treatment with vehicle or hr-inhibin and for 6 h afterwards. Treatment of wethers with testosterone (Experiment 1) resulted in a significant decrease in the plasma concentrations of LH and number of LH pulses per hour but the magnitude of these reductions did not differ between seasons. Testosterone treatment had no effect on LH secretion in GnRH-pulsed HPD wethers in either season and treatment with hr-inhibin did not affect LH secretion in wethers or HPD wethers in any instance. Plasma concentrations of FSH were significantly (P<0.05) reduced following treatment with testosterone alone during the breeding season but not during the non-breeding season. FSH levels were reduced to a greater extent by treatment with hr-inhibin but this effect was not influenced by season. During the non-breeding season, the effect of hr-inhibin to suppress FSH secretion was enhanced in the presence of testosterone. These experiments demonstrate that the negative feedback actions of testosterone on the secretion of LH in this breed of rams occurs at the hypothalamic level and is not influenced by season. In contrast, both testosterone and inhibin act on the pituitary gland to suppress the secretion of FSH and these responses are affected by season. Testosterone and inhibin synergize at the pituitary to regulate FSH secretion during the non-breeding season but not during the breeding season.

Analysis of Variance↗

PubMed2001

Androgen receptors are only present in mesenchyme-derived dermal papilla cells of red deer (Cervus elaphus) neck follicles when raised androgens induce a mane in the breeding season.

Red deer stags produce an androgen-dependent mane of long hairs only in the breeding season; in the non-breeding season, when circulating androgen levels are low, the neck hair resembles the rest of the coat. This study was designed to determine whether androgen receptors are present in deer follicles throughout the year or only in the mane (neck) follicles when circulating testosterone levels are high in the breeding season. Although androgens regulate much human hair growth the mechanisms are not well understood; they are believed to act on the hair follicle epithelium via the mesenchyme-derived dermal papilla. The location of androgen receptors in the follicle was investigated by immunohistochemistry and androgen binding was measured biochemically in cultured dermal papilla cells derived from mane and flank follicles during the breeding season and from neck follicles during the non-breeding season. Immunohistochemistry of frozen skin sections using a polyclonal antibody to the androgen receptor localised nuclear staining only in the dermal papilla cells of mane follicles. Saturation analysis assays of 14 primary dermal papilla cell lines using [(3)H]-mibolerone demonstrated high-affinity, low-capacity androgen receptors were present only in mane (breeding season neck) cells; competition studies with other steroids confirmed the specificity of the receptors. Androgen receptors were not detectable in cells from either the breeding season flank nor the non-breeding season neck follicles. The unusual biological model offered by red deer of androgen-dependent hair being produced on the neck in the breeding, but not the non-breeding season, has allowed confirmation that androgen receptors are required in follicle dermal papilla cells for an androgen response; this concurs with previous human studies. In addition, the absence of receptors in the non-breeding season follicles demonstrates that receptors are not expressed unless the follicle is responding to androgens. Androgen receptors may be induced in mane follicles by seasonal changes in circulating hormone(s).

Androgens↗

PubMed1995

Seasonal variation in fitness parameters in competitive athletes.

In many sports, training for successful competition has become virtually a year-round endeavour. To assist in better preparation, a competitor's year may be divided into phases such as off-season and in-season, indicating reduced or increased competition commitments, respectively. A number of studies have described the effects of seasons or periods of competition, training, detraining and reduced training on aspects of physical fitness. Depending on performance level, the type of sport and the fitness parameter in question, the swings in fitness variables reported may be as high as 18% from one season to another. In elite competitors, anaerobic parameters, heart frequencies, subcutaneous fat, flexibility and haemoglobin levels remain relatively unchanged throughout the year. Aerobic metabolism and muscular strength may demonstrate noticeable (mostly unfavourable) changes, and plasma hormonal levels normally follow changes in training intensities. Aspects related to long term fatigue and genetics, and to appropriate training are just a few explanations for these observations. It is still not known whether greater fitness gains attainable with longer off-season training programmes can be successfully maintained over the duration of the competition season. However, the consensus would seem to be that specialised training (based on technique and competition tactics only) is inadequate for fitness maintenance and/or improvements. This is perhaps supported by the general trends found in the literature regarding muscular strength: while supervised off-season conditioning programmes may result in significant improvements for both recreational and competitive athletes, no such changes are normally observed after competition seasons. These findings may reflect, amongst other factors, a lack of optimal training intensity to bring about strength increases during in-season periods. In novices and in athletes at low competitive levels, training seasons may lead to considerable functional improvements of the cardiorespiratory system, coupled with occasional increases in muscular strength and decreases in body fat. Relatively low fitness levels at the beginning of training have been put forward as an explanation for these improvements. Seasons of training and competition result in no significant changes in flexibility measurements. Similar changes to those found in novices and in athletes at low competitive levels may also be seen in children and adolescents engaged in sport, although their fitness improvements are consistent with normal patterns of growth and development. No differences have been identified between male and female athletes participating at different competition levels.

Adolescent↗

PubMed1990

Effects of percentage Brahman and Angus breeding, age-season of feeding and slaughter end point on feedlot performance and carcass characteristics.

Steers (n = 165) of known percentage Brahman (B) and Angus (A) breeding were used to study effects of breed group (A, 3/4A:1/4B, 1/2A:1/2B, 1/4A:3/4B), age-season of feeding (calves fed during the cool season vs yearlings fed during the warm season) and slaughter end point (less than .90, 1.0 to 1.15, 1.27 to 1.40, greater than or equal to 1.5 cm of adjusted fat over the ribeye) on feedlot performance and carcass characteristics. The 1/2B and 3/4B steers had heavier (P less than .05) initial and final feedlot weights than the A and 1/4B steers and higher (P less than .05) unshrunk ADG than the A steers did. Breed types did not differ for feed efficiency. Yearling steers fed in the warm season had higher (P less than .05) unshrunk ADG than calves fed in the cool season, but ADG calculated on an empty-rumen basis did not differ between the two age-seasons of feeding. Calves fed in the cool season were more efficient (P less than .05) than yearlings fed in the warm season when efficiency was expressed on an empty-rumen basis; however, on a live weight basis there was no difference in feed efficiency. No breed group by age-season of feeding interactions on performance were detected. Slaughter end point did not significantly affect feed efficiency on an empty-rumen basis. The 1/2B and 3/4B steers had smaller ribeye areas (REA) per 100 kg hot carcass and lower marbling scores than the 1/4B and A steers. Yearlings fed in the warm season produced heavier carcasses (P less than .05) than calves fed in the cool season. As s.c. fat thickness at slaughter increased, hot carcass weight and numerical yield grade increased, whereas REA per 100 kg of hot carcass decreased. Marbling also increased as fatness increased up to about 1.5 cm subcutaneous fat.

Adipose Tissue↗

PubMed1992

Postweaning growth and reproduction of beef heifers exposed to calve at 24 or 30 months of age in spring and fall seasons.

Angus and Angus x Hereford heifer calves born in spring or fall seasons were allotted by weight at weaning to be exposed to bulls for calving at either 24 or 30 mo of age. Comparisons were made 1) within birth season--heifers born in the same season were first exposed to bulls at either 14 to 16 or 19 to 22 mo of age and 2) within breeding season--heifers born in different but consecutive seasons (spring-fall or fall-spring) were exposed to bulls during the same season but at different ages. Spring-born heifers exposed for 30-mo calving were heavier (336 vs 302 kg) and taller (P less than .01) at breeding than those exposed for 24-mo calving. Also, more were observed in estrus and became pregnant (P less than .01) during a 21-d AI breeding period, but season-long (63 d) pregnancy rates were not different (86%). Fall-born heifers exposed for 24- or 30-mo calving were similar for weight, hip height, and body condition score (BCS) at breeding, but season-long pregnancy rates were 71 and 94%, respectively (P less than .01). Although fall-born heifers were heavier at weaning (P less than .01), spring-born heifers were heavier, taller, and had higher BCS at breeding (P less than .01), regardless of age. Within spring breeding seasons, breeding weight and initial reproduction were not affected by heifer age. Within fall breeding seasons, older heifers were larger (P less than .01) and had greater reproductive performance (P less than .05) than younger heifers. Age at breeding, irrespective of season, consistently affected (P less than .01) both hip height (116 vs 113 cm) and pelvic area (209 vs 178 cm2) for older vs younger heifers, respectively. These data indicate that heifers exposed for 30-mo first calving are heavier, taller, have larger pelvic area, and have greater reproductive performance than those exposed for 24-mo first calving.

Age Factors↗

PubMed2006

Effects of season and breed on the feeding behavior of multiparous lactating sows in a tropical humid climate.

The effects of breed and season on performance and feeding behavior were studied during 76 lactations in multiparous Large White (LW; n = 17) and Creole (CR; n = 23) sows reared in a humid tropical climate. The experiment was conducted in Guadeloupe (French West Indies, latitude 16 degrees N, longitude 61 degrees W) between May 2002 and July 2004. Average daily ambient temperature was greater during the hot season than during the warm season (26.0 vs. 23.8 degrees C), but relative humidity was similar in both seasons (85% on average). The daily fluctuations of ambient temperature and relative humidity were similar for both seasons. At farrowing, BW was lower (187 vs. 265 kg) and backfat thickness was greater (40 vs. 22 mm) in CR than in LW sows (P < 0.01). Sows were offered feed ad libitum between the fifth and the 26th day of lactation. There was a breed x season interaction (P < 0.05) for ADFI. During the hot season the reduction of ADFI was more pronounced in LW than in CR sows (-1,100 vs. -300 g/d). Irrespective of breed and season, the daily number of meals was 9.0. The meal size and the rate of feed intake were greater in LW than in CR sows, respectively (555 g and 153 g/min vs. 390 g and 83 g/min; P < 0.01). The diurnal proportion of ADFI was greater in CR than in LW sows (0.60 vs. 0.41; P < 0.01). The reduction in ADFI in LW sows during the hot season was mainly related to a reduction in feed intake during the day rather than during the night (-1.3 vs. -0.2 kg; P < 0.01). Duration of standing was not affected by breed or season, and it averaged 120 min/day. This study confirms the negative effect of the hot season on feeding behavior of lactating sows. It also suggests a better acclimation to daily high temperatures and a greater heat tolerance in CR compared with LW sows, at least for eating behavior.

Animals↗

PubMed2006

Seasonality of reproduction in gilts and sows.

In the wild, the pig adapts her reproductive functions according to the seasonal changes in the environment, such as the ambient temperature and availability of food. Like in other short day seasonal breeders, breeding season is favoured in the mid winter in order to provide the offspring with the best chances to survive four months later. Seasonal changes in environment are perceived mainly by the ability of the pig to recognise seasonal changes in photoperiod. This information is mediated through changes in the activity of the pineal gland to secret melatonin, essentially by the same mechanism as reported for other mammals. Stimulation of melatonin receptors located in the hypothalamus has a significant role for the release of GnRH and subsequent gonadotrophin release from the pituitary. Management and nutrition related factors determine the degree of seasonal effects on reproduction in the commercial piggery environment. Significant improvements in fertility in herds suffering from seasonal infertility are achievable by providing gilts and sows with abundant feed after mating. Attempts to alleviate the seasonal effects on fertility by applying light programs are underway and may lead to significant improvements in productivity of the domestic pig in the long run. Hormonal treatments may be somewhat effective, but not a sustainable solution to seasonal infertility. In conclusion, seasonal infertility is a photoperiod induced phenomenon that can be manipulated by changes in photoperiod and by accounting for season as a significant factor when feeding strategies are applied in commercial piggeries.

Animal Nutritional Physiological Phenomena↗

PubMed1991

Ability of Anopheles gambiae mosquitoes to transmit malaria during the dry and wet seasons in an area of irrigated rice cultivation in The Gambia.

The seasonality of malaria transmission was studied in a Gambian village situated in an area where rice was cultivated. Observations were made during two dry seasons, when pump-fed irrigation was used to grow rice, and in the intervening rainy season, when rice was cultivated using a combination of irrigated and rain-fed paddies. Clinical episodes of malaria were mainly confined to the months during and soon after the rainy season. In the wet season the prevalence of parasitaemia was higher in febrile subjects than in afebrile controls but the reverse applied during the dry seasons. However, the biting rates of Anopheles gambiae complex mosquitoes in the two dry seasons (2.5 and 0.8 bites/child/night respectively) were greater than or similar to that in the rainy season (0.6 bites/child/night). The proportion of human bloodmeals (0.53 vs 0.75) and the survival of mosquitoes (parity rates of 0.41 vs 0.58) were both lower in the dry seasons than in the rains. The low prevalence of morbidity due to malaria in the dry season and the observed fall in the sporozoite rate may therefore have been due to a reduction in the vectorial capacity of the An. gambiae population. However, reduced transmission in the dry season may also have been due to the direct effect of high temperatures on the parasite in the vector.

Age Factors↗

PubMedDate not supplied

Effects of seasonal variations, acute hypothermia and physostigmine on cardiac acetylcholine, tissue glycogen and blood sugar concentrations in frogs.

The effects of seasonal variations and the effects of acute hypothermia (8.0 degrees) and/or physostigmine (PHY) in different seasons have been studied on the tissue glycogen, cardiac acetylcholine (ACh) and blood sugar contents in frogs. Seasonal variations had no significant effect on cardiac cholinergic activity. However, cardiac ACh concentration was significantly reduced by hypothermia in all seasons. The extents of increase in cardiac ACh in PHY pretreated hypothermic frogs indicate that hypothermia depresses cardiac cholinergic acitity much more in summers than in rainy and winter seasons. The tissue glycogen contents and blood sugar concentrations were significantly lower in winter season than those in summer and rainy seasons. Hypothermia produced marked tissue glycogenolysis and hyperglycaemia during summer and rainy seasons and not during winters. In general PHY had no effect on tissue glycogen contents in any season, but it produced hyperglycaemia during rainy and winter seasons. PHY pretreatment increased cardiac, hepatic and muscle glycogen contents and produced hyperglycaemia in hypothermic winter frogs, and it increased ventricular and muscle glycogen contents during summer and hepatic glycogen during rainy seasons, there being no significant effects on blood sugar.

Acetylcholine↗

PubMed2005

Physiological and anthropometric characteristics of junior rugby league players over a competitive season.

This study investigated the physiological and anthropometric characteristics of junior rugby league players over a competitive season. Forty-five rugby league players were allocated into training (n = 36) and nonexercise control (n = 9) groups. The training group participated in 2 field-training sessions each week with training loads, match loads, and injury rates recorded. Subjects performed measurements of standard anthropometry (height, body mass, and sum of 7 skinfolds), muscular power (vertical jump), speed (10-, 20-, and 40-m sprint), agility ('L run'), and estimated maximal aerobic power (multi-stage fitness test) in December (off-season), March (preseason), May (midseason), and August (end-season). Training loads progressively increased in the general preparatory phase of the season (preseason period), and declined slightly during the competitive phase of the season. Match intensity and match loads decreased throughout the season. Increases in estimated maximal aerobic power and muscular power and reductions in skinfold thickness occurred during the general preparatory phase of the season, and were maintained throughout the competitive phase of the season. These findings suggest that high training loads in the general preparatory phase of the season and low match loads in the competitive phase of the season allow junior rugby league players to maintain a high level of fitness throughout an entire competitive season.

Adolescent↗

PubMed1996

Once daily intranasal fluticasone propionate (200 micrograms) reduces nasal symptoms and inflammation but also attenuates the increase in bronchial responsiveness during the pollen season in allergic rhinitis.

BACKGROUND: Fluticasone propionate aqueous nasal spray, a new topical corticosteroid, has been proved to be an effective treatment for seasonal allergic rhinitis. OBJECTIVES: We studied the effect of fluticasone propionate on nasal symptoms, circulating eosinophils, and nasal inflammation in patients with seasonal allergic rhinitis after high-load pollen exposure. Moreover, we examined its efficacy in preventing the increase in bronchial responsiveness to methacholine (PD20) during the pollen season. METHODS: We conducted a double-blind, placebo-controlled, parallel-group study in patients who had a history of allergic rhinitis in response to pollens of grass and Parietaria species and were living in northern Italy. After a run-in period of 2 weeks, 24 patients were treated with fluticasone propionate (200 micrograms, once daily), and 26 patients received matched placebo for 6 weeks, starting from the beginning of the pollen season. Assessment of efficacy was based on scores of daily nasal symptoms. Nasal lavage was performed at the end of the season, and differential cell count was expressed as percent of total cells. PD20 methacholine was measured at the beginning and end of the season and after the season had ended. RESULTS: Fluticasone propionate significantly reduced nasal obstruction, itching, and rhinorrhea. Eosinophils in blood (p < 0.01) and nasal lavage (p < 0.001) were also reduced. Moreover, fluticasone significantly attenuated the decrease in mean PD20 methacholine (from 1.95 to 0.89 mg) compared with placebo (from 1.38 to 0.37 mg: p < 0.01). After the season, no difference in PD20 methacholine was found between treatment groups. CONCLUSIONS: The results of this study indicate that fluticasone propionate is effective in decreasing nasal symptoms and eosinophil inflammation in patients with seasonal allergic rhinitis after high-load pollen exposure. Our results also demonstrate that treatment with fluticasone propionate partially prevents the increase in bronchial responsiveness provoked by the inhalation of seasonal pollens in allergic rhinitis.

Administration, Intranasal↗

PubMed1999

Basophil histamine release, IgE, eosinophil counts, ECP, and EPX are related to the severity of symptoms in seasonal allergic rhinitis.

BACKGROUND: Serum specific IgE, basophil histamine release, and blood eosinophil parameters are associated with allergic rhinitis, but investigations of the relationship to the severity of allergic symptoms are few and conflicting. Our study aimed to investigate the seasonal changes in the following laboratory tests: specific IgE, basophil histamine release, eosinophil counts, and serum and plasma eosinophil cationic protein (ECP) and eosinophil protein X (EPX), and to analyze, in detail, the relationship of each individual test to the severity of symptoms in rhinitis patients allergic to both birch and grass pollen. METHODS: The above tests were performed on blood samples obtained from 49 allergic rhinitis patients during the birch-pollen season, during the grass-pollen season, and after the seasons. Symptom-medication diaries were filled in during both pollen seasons. We used partial least square (PLS) analysis to establish an optimal statistical link between the symptom score and medication and the laboratory tests, in an investigator-independent way. RESULTS: Increases in specific IgE, basophil histamine release, eosinophil counts, serum ECP and EPX, and plasma EPX were observed from the birch-pollen season to the grass-pollen season, followed by a decrease from the grass-pollen season to after the pollen seasons, except for the specific IgE. No seasonal changes in plasma ECP and total IgE were seen. The PLS analysis found a relationship between symptom score and medication and the aggregate laboratory tests (F-test value 40.2, correlation 0.34 for the cumulative relation). However, the variation in laboratory tests could explain only half of the total variation in symptoms and less than a quarter of the total variation in medication. The symptom score and, to a minor degree, medication were especially correlated with the basophil histamine-release results, with a decreasing relevance of specific IgE, eosinophil counts, total IgE, serum and plasma EPX, and serum ECP. Plasma ECP was not related to the symptom score and medication. CONCLUSIONS: A significant relationship between the severity of allergic rhinitis and various allergic inflammatory markers was found but could account for only a minor part of the variation in the patients' evaluation of their disease.

Adolescent↗

PubMed1998

The clinical role of specific IgE and IgG4 antibodies in patients having immunotherapy for seasonal allergic rhinitis.

This study was designed to investigate the clinical role of specific IgG4 and IgE responses in patients during immunotherapy for seasonal allergy. The study included 109 patients with seasonal allergic rhinitis due to Japanese cedar pollens. They were divided into the control group and the immunotherapy group. Serum samples were obtained at the start of immunotherapy, before the pollen season and during the season, to determine serum specific IgE and IgG4. In the control group specific IgE was significantly increased, but specific IgG4 was not changed during the pollen season. In the immunotherapy group specific IgE was not significantly increased, but specific IgG4 was significantly increased during the season. In the patients having immunotherapy for 2 years or less, the seasonal increase in specific IgG4 related to the magnitude of the clinical effect. In the patients having immunotherapy for 3 years or more, the seasonal increase in specific IgE related to the magnitude of the clinical effect. In conclusion, the specific IgG4 response and specific IgE response during the pollen season make a significant contribution to the clinical effect of immunotherapy. However, modulation of specific IgE and IgG4 responses out of the pollen season was unlikely to be an important phenomenon related to the clinical effect of immunotherapy.

Adolescent↗

PubMed1995

Seasonal variation in human reproduction: environmental factors.

Almost all human populations exhibit seasonal variation in births, owing mostly to seasonal variation in the frequency of conception. This review focuses on the degree to which environmental factors like nutrition, temperature and photoperiod contribute to these seasonal patterns by acting directly on the reproductive axis. The reproductive strategy of humans is basically that of the apes: Humans have the capacity to reproduce continuously, albeit slowly, unless inhibited by environmental influences. Two, and perhaps three, environmental factors probably act routinely as seasonal inhibitors in some human populations. First, it seems likely that ovulation is regulated seasonally in populations experiencing seasonal variation in food availability. More specifically, it seems likely that inadequate food intake or the increased energy expenditure required to obtain food, or both, can delay menarche, suppress the frequency of ovulation in the nonlactating adult, and prolong lactational amenorrhea in these populations on a seasonal basis. This action is most easily seen in tropical subsistence societies where food availability often varies greatly owing to seasonal variation in rainfall; hence births in these populations often correlate with rainfall. Second, it seems likely that seasonally high temperatures suppress spermatogenesis enough to influence the incidence of fertilization in hotter latitudes, but possibly only in males wearing clothing that diminishes scrotal cooling. Since most of our knowledge about this phenomenon comes from temperate latitudes, the sensitivity of spermatogenesis in both human and nonhuman primates to heat in the tropics needs further study. It is quite possible that high temperatures suppress ovulation and early embryo survival seasonally in some of these same populations. Since we know less than desired about the effect of heat stress on ovulation and early pregnancy in nonhuman mammals, and nothing at all about it in humans or any of the other primates, this is an important area for future research. Third, correlational data suggest that there may be some degree of regulation of reproduction by photoperiod in humans at middle to higher latitudes. Populations at these latitudes often show a peak in presumed conceptions associated with the vernal equinox. On the other hand, evidence gathered by neuroendocrinologists tends to argue against reproductive photoresponsiveness in humans.

Animals↗