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At least 595 records · Page 33Linked to original sources
PubMed1998

Nasal eosinophilia and IL-5 mRNA expression in seasonal allergic rhinitis induced by natural allergen exposure: effect of topical corticosteroids.

BACKGROUND: Nasal allergen provocation in patients with allergic rhinitis leads to expression of the proeosinophilic cytokines IL-5 and GM-CSF and tissue eosinophilia. OBJECTIVE: We sought to examine the effect of natural seasonal allergen exposure on IL-5 and GM-CSF mRNA expression and nasal eosinophilia and to evaluate the effects of topical corticosteroid therapy on these responses. METHODS: Nasal biopsy specimens were collected from 46 grass pollen-sensitive patients with seasonal rhinitis before the grass pollen season. A second biopsy specimen was collected during the pollen season, by which time patients had received 6 weeks treatment with either fluticasone propionate (200 micro(g) twice daily) or placebo nasal spray. RESULTS: Fluticasone treatment was clinically effective (P <.005). Patients receiving placebo, but not fluticasone, showed increased numbers of epithelial and submucosal EG2+ eosinophils (P <.005) and IL-5 and GM-CSF mRNA-expressing cells (P <.0001) during the pollen season. Colocalization experiments showed that greater than 80% of IL-5 mRNA-expressing cells were submucosal CD3+ T cells in both groups. The numbers of submucosal CD3+ T cells did not increase during the pollen season or decrease with fluticasone treatment. Fluticasone also inhibited IL-5 secretion by grass pollen-stimulated peripheral blood T cells from patients with seasonal rhinitis (n = 5, inhibitory concentration of 50% = 10(-9) to 10(-10) mol/L). CONCLUSIONS: These results suggest that topical corticosteroids may reduce eosinophilia in seasonal rhinitis by inhibiting T cell IL-5 production.

Administration, Intranasal↗
PubMed2001

The effects of age, season and fertility status on plasma and intratesticular insulin-like growth factor I concentration in stallions.

The purposes of this study were to establish the basal plasma and testicular insulin-like growth factor-I (IGF-I) values for stallions ranging in age from 6 months to 23 years and to determine if IGF-I could be used as a marker for declining fertility. Blood and testes were obtained from 28 light horse stallions and colts. Of the 28 stallions, 22 were considered fertile and were categorized by age (<2 y, 5 to 10 y, 11 to 15 y, and 16 to 23 y); 12 age-matched stallions were grouped as to fertility status (fertile, subfertile, infertile); and all 28 stallions were grouped as to season of castration (breeding season vs. non-breeding season). In colts less than 2 years of age, IGF-I concentrations in plasma and testicular extracts were higher (P < 0.01) than in the other age groups and were higher in the breeding season than in the non-breeding season (P < 0.01). No significant differences in plasma or testicular extract concentrations of IGF-I were found among fertility groups. The results of this study demonstrate that plasma and testicular IGF-I levels are high in stallions younger than 2 years of age and then decline and plateau in stallions older than 5 years of age, suggesting that IGF-I may be involved in testicular development. The results allude to a possible seasonal effect on IGF-I production. However, it is difficult to separate true seasonality and the effect of age as only those stallions less than 2 years old exhibited variation between seasons. The IGF-I does not appear to have a direct relationship with declined fertility in the stallions tested, suggesting that IGF-I may not be a reliable biomarker for the diagnosis of subfertility and infertility.

Aging↗
PubMed1999

Effects of season and phase of the estrous cycle on steroidogenesis and LH-FSH sensitivity of large ovine follicles perfused in vitro.

The aims of this study were to compare steroïdogenesis (progesterone, androstenedione and estradiol production) and response to LH and FSH challenge by whole perifused follicles 4 to 5.5 mm in diameter, obtained at different periods of the breeding season (onset, middle, end), during anestrus and the luteal phase. We have observed that all follicles do not have the same steroïdogenetic potential and do not respond with the same intensity to LH and FSH. At the middle of the breeding season, LH and FSH supplementation was ineffective in increasing progesterone secretion by follicles (0.19+/-0.05 vs. 0.20+/-0.03 ng/mL). In contrast, gonadotrophin challenge elicited significant (P<0.05) increases in androstenedione (0.94+/-0.34 vs. 0.35+/-0.09 ng/mL) and estradiol (120+/-11 vs. 49+/-10 pg/mL) production immediately after its administration. At the onset of the breeding season, steroidogenesis was identical under both basal and gonadotrophin-stimulated conditions unlike that in middle of the breeding season. However follicles were more sensitive to the gonadotrophin challenge in terms of estradiol production than those collected at the middle of the breeding season (220+/-45 vs. 120+/-11 pg/mL). Follicles obtained at the end of the breeding season featured higher progesterone (2.61+/-0.81 vs. 0.19+/-0.05 ng/mL; P<0.05) and lower estradiol production (10+/-3 vs. 49+/-10 pg/mL; P<0.05) that was not influenced by LH and FSH. Basal androstenedione secretion was comparable to that observed at the middle of the breeding season (0.42+/-0.10 vs. 0.35+/-0.09 ng/mL), but the response to stimulation was significantly higher (1.82+/-0.61 vs. 0.94+/-0.34 ng/mL; P<0.05). In anoestrus and the luteal phase, follicles presented higher progesterone and androstenedione and lower estradiol concentrations (P<0.05) compared with those obtained during the follicular phase at the middle of the breeding season. In the luteal phase, follicles remained capable of responding to LH-FSH challenge by increasing estradiol secretion (9+/-1 before and 21+/-6 pg/mL after LH-FSH; P<0.05). In contrast, in the luteal phase, estradiol production was not increased by LH-FSH challenge (7+/-2 vs. 12+/-4 pg/mL).

Androstenedione↗
PubMed1986

Developmental and seasonal changes in canary song and their relation to changes in the anatomy of song-control nuclei.

Young male canaries become sexually mature in late winter, 8-12 months after hatching. During the months between hatching and sexual maturity they develop adult song. The successive stages in the development of adult song are subsong, plastic song, and stable or full song. Once stable song is achieved it lasts for the duration of the breeding season. After the end of the breeding season there is a recurrence of song instability during summer and early fall. This plastic song is followed, once more, by stable song. New song syllables are added to the song of adult male canaries and some of the earlier syllables disappear. The song repertoire sung at 2 years of age is substantially larger, and different, from that sung during the first breeding season, when the birds were 1 year old. A comparable change occurs between the second and third breeding seasons. Most of the syllables acquired by adult males are formed during the summer-fall period of song instability. Developmental and seasonal changes in song are accompanied by anatomical changes in two forebrain nuclei known to be involved in song control, the hyperstriatum ventralis, pars caudalis (HVc), and the robust nucleus of the archistriatum (RA). HVc and RA grow during the subsong and plastic song periods of song development. These nuclei reach adult size by the time stable adult song is first produced, and retain this size during the breeding season. However, the size of HVc and RA diminishes by late summer, when it becomes comparable to that of a 3- to 4-month-old bird. This reduction in size is temporary and has been corrected by the following breeding season. It is suggested that these seasonal changes in volume reflect circuit changes which are under hormonal control, and that these changes are related to processes of learning and, possibly, forgetting. Despite earlier reports of left hemispheric dominance in canary song production, we failed to find any evidence of right-left systematic differences in the size of HVc and RA during development or in adulthood. Various hypotheses relating song learning to changes in the underlying anatomy are offered.

Animals↗
PubMed2003

The stability of the Seasonal Pattern Assessment Questionnaire score index over time and the validity compared to classification according to DSM-III-R.

BACKGROUND: In 1984, Rosenthal et al. described a group of patients characterised by repeated winter depression with atypical symptoms eventually followed by summer mania or hypomania (seasonal affective disorder, SAD). The relationship between SAD and the classical manic-depressive disorder is uncertain. The aim of this study was to validate the Seasonal Pattern Assessment Questionnaire (SPAQ) classification in relation to the DSM-III-R criteria of seasonal patterns in a group of patients with bipolar affective disorder and to evaluate the stability of the SPAQ score index over time. METHODS: A group of bipolar patients were followed for 3 years with examinations every third month and at hospitalisation. At inclusion and at each following examination the patients were rated with the Hamilton Depression Rating Scale, the Newcastle Depression Rating Scale, and the Bech-Rafaelsen Mania Rating Scale. At inclusion and once a year the patients completed the SPAQ. RESULTS: Fifty-six patients agreed to participate and 46 patients completed 1 year or more. Eight patients, all women, had at least one SPAQ score index (SSI) of 11 or more. Women scored significantly higher than men on SPAQ. The test/re-test reliability of SSI between two consecutive years was good, but decreased as the time difference between tests increased. Moreover, we found no relation between seasonal variations of affective episodes according to SSI and DSM-III-R. LIMITATIONS: The group of patients with seasonality according to DSM-III-R or SSI was small. CONCLUSION: The validity of SSI between two consecutive years is good, but decreases as the time difference between tests increases. There is no relationship between seasonality defined by DSM-III-R and SSI. Female bipolar patients show, as the general population, seasonal variations in mood, energy, sociality, appetite, and sleep independently of their affective episodes. SSI cannot be used for the prediction of seasonal variation in a group of bipolar patients.

Bipolar Disorder↗
PubMed2002

Participatory analysis of seasonal incidences of diseases of cattle, disease vectors and rainfall in southern Sudan.

During an investigation into a chronic wasting disease in southern Sudanese cattle, a participatory appraisal method called a 'seasonal calendar' was used to understand local perceptions of seasonal variations in cattle diseases, disease vectors, intermediate hosts and rainfall. Repetition of a standardized seasonal calendar with Dinka informants demonstrated good reproducibility of the method. Comparison of rainfall data produced by seasonal calendars and objective measures of rainfall demonstrated good validity of the seasonal calendar method. Subjective assessment of seasonal calendar scoring patterns by veterinarians indicated that herders' perceptions of seasonal populations of biting flies, ticks and snails were similar to modern veterinary knowledge. The uses of seasonal calendars in veterinary epidemiology are discussed.

Animal Husbandry↗
PubMed2002

Seasonal variability of mercury and heavy metals in roe deer (Capreolus capreolus) kidney.

The seasonal variability of Hg, Pb, Cd and Zn was determined in the kidney of 164 roe deer, shot in three areas of Slovenia in 1998. We found a strong seasonal influence on Hg and Pb levels, which were significantly higher in late summer and early autumn. Cd and Zn levels showed a similar seasonal pattern, although not so pronounced; for these elements differences among periods were probably not a consequence of season per se. Seasonal variability in metal levels in roe deer kidney originated in both quantitative and qualitative differences in nutrition of the species. Since the seasonal peaks for the majority of metals appeared in a very narrow summer autumnal period (August-September), it seems that some plant taxons, such as fungi, might represent an important pathway for heavy metal intake into the mammalian organism. The season of sample collection has to be considered whenever using wildlife as an accumulative bioindicator of environmental pollution. Moreover, the influence of the season should be born in mind whenever a hazard due to accumulation of heavy metals along the food chain is assessed.

Animals↗
PubMed1997

The GnRH system of seasonal breeders: anatomy and plasticity.

Seasonal breeders, such as sheep and hamsters, by virtue of their annual cycles of reproduction, represent valuable models for the study of plasticity in the adult mammalian neuroendocrine brain. A major factor responsible for the occurrence of seasonal reproductive transitions is a striking change in the responsiveness of gonadotropin-releasing hormone (GnRH) neurons to the inhibitory effects of gonadal steroids. However, the neural circuitry mediating these seasonal changes is still relatively unexplored. In this article, we review recent findings that have begun to define that circuitry and its plasticity in a well-studied seasonal breeder, the ewe. Tract tracing studies and immunocytochemical analyses using Fos and FRAs as markers of activation point to a subset of neuroendocrine GnRH neurons in the MBH as potential mediators of pulsatile GnRH secretion. Because the vast majority of GnRH neurons lack estrogen receptors, seasonal changes in responsiveness to estradiol are most probably conveyed by afferents. Two possible mediators of this influence are dopaminergic cells in the A14/A15 cell groups of the hypothalamus, and estrogen receptor-containing cells in the arcuate nucleus that project to the median eminence. The importance of GnRH afferents in the regulation of season breeding is underscored by observations of seasonal changes in the density of synaptic inputs onto GnRH neurons. Thyroid hormones may participate in this remodeling, because they are important in seasonal reproduction, influence the morphology of other brain systems, and thyroid hormone receptors are expressed within GnRH neurons. Finally, in the hamster, neonatal hypothyroidism affects the number of caudally placed GnRH neurons in the adult brain, suggesting that thyroid hormones may influence development of the GnRH system as well as its reproductive functions in the adult brain.

Animals↗
PubMed2001

Seasonal differences in ram seminal plasma revealed by partition in an aqueous two-phase system.

Seminal plasma plays an important role in maturation of spermatozoa through hormonal, enzymatic and surface-modifying events. We have previously shown that adsorption of seminal plasma proteins (SPPs) to the sperm cell surface partially restores the functional characteristics of damaged spermatozoa, reproducing those of live cells. In the present report, we investigate the hypothesis that seasonal differences in seminal plasma could affect its ability to recover membrane integrity of cold-shocked sperm. The effect of seminal plasma proteins, obtained in breeding (bsSPPs) and non-breeding (nbsSPPs) season, on cold-shocked ram spermatozoa previously freed from seminal plasma, was analysed by centrifugal counter-current distribution (CCCD) in an aqueous two-phase system as well as membrane integrity determination by fluorescence markers. Cold-shock treatment greatly lowered cell viability in both breeding and non-breeding season spermatozoa. The cold-shocked sperm viability obtained was approximately 20%. The loss of heterogeneity and the decrease in viability revealed by CCCD analysis was reversed by the addition of increasing amounts of bsSPP, which induced restoration of the surface characteristics of viable-like spermatozoa, as well as an increase in the number of recovered viable sperm. However, this restoring effect was much lower when nbsSPPs were added, even in a sixfold higher concentration than used with bsSPPs. Incubation of cold-shocked cells with both kinds of proteins performed in both seasonal periods, showed that the recovering effect was related to the season when the plasma sample was obtained rather than to the semen season. The addition of bsSPPs to cold-shocked sperm accounted for a nearly 50% reversion for both studied breeding seasons. However, the reversion percentages obtained with nbsSPPs were significantly lower (P<0.05) than those found with bsSPPs in both studied seasonal periods. This different reversion capacity of bsSPPs and nbsSPPs was related to a different protein composition, as revealed by comparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. The bands of 20, 21, 24, 36 and 67 kDa of the bsSP sample profile decreased in winter-spring SP, and were even less intensely stained in summer SP. Densitometric analysis of the stained gel patterns allows automatic comparison among the separated bands, and revealed an important decrease in the content of several bands. The 21.5 kDa band showed the highest decrease, lowering to 14% in June-August plasma with respect to the value obtained in September-December plasma.

Animals↗
PubMed1997

Long-term patterns in seasonality of insulin-dependent diabetes mellitus diagnosis in Austrian children.

The analysis of the seasonal pattern of incidence of childhood insulin-dependent diabetes mellitus in Austria was carried out among cases where the child was under the age of 15 when diagnosed between 1979 and 1993. The cases are registered in the nationwide population-based Austrian insulin-dependent diabetes mellitus registry. Seasonal variation was compared between boys and girls and between three 5-year age groups. We also tested whether the seasonal pattern changed over the 15-year observation period. We found a significant seasonal variation among boys aged 10-14 and girls aged 5-14, while in the 0-4 years age group no seasonal pattern could be demonstrated. Two peaks in incidence were identified during a calendar year (February-March and September-October) for girls aged 5-14. For boys aged 10-14, a yearly cycle was found with a peak in January and October. An extension of the Poisson regression model for testing seasonality by Jones et al. was developed to allow for estimation of a time-dependent amplitude of the seasonal component. The annual incidence rate increased by 36% during the observation period, but no significant change in seasonal pattern could be demonstrated.

Adolescent↗
PubMed2006

Additional confirmation for the effect of environmental light intensity on the seasonality of human conceptions.

Causality for the seasonality of human births, which affects populations wordwide, has been a profound mystery for nearly two centuries. Most explanations for seasonality fail because of inconsistent global application. In two previous studies, Cummings (2002, 2003) hypothesized that human reproduction has been responsive to changes in both seasonal environmental light intensity (surface luminosity) and photoperiod. Except at higher latitudes, photoperiod is of secondary importance to that of environmental light intensity. Because of a lack of data, the presence or lack of cloud cover is used as a general proxy for environmental light intensity. These studies show a positive correlation between conceptual seasonality and cloud cover on a worldwide basis, and propose that there is a delay between exposure to increased light and the onset of conceptions. This delay is three months at higher latitudes and one to two months for lower latitudes. Both studies suggest that an excellent means of hypothesis confirmation would be to provide one or more examples of how a seasonal change in cloud cover might alter the number of conceptions in subsequent months. The present study tests this hypothesis. The percentage of possible sunshine and averaged sunshine hours are used to investigate their influence on seasonality of births in Germany and the Netherlands. The evidence shows that a seasonal change in environmental light intensity preceded a change in the peak months for conceptions in Germany and the Netherlands. Although secondary influences are possible, the primary reason for this transition in peak conceptual months seems to be related to the seasonal changes in environmental light intensity for both countries. Although this transitional relationship was predicted in Cummings (2002, 2003), further research is required, especially with regard to more precise measurements of environmental light intensity and its physiological effect on the human endocrine system.

Birth Rate↗
PubMed2001

Basophil activation during pollen season in patients monosensitized to grass pollens.

BACKGROUND: Basotest is a new basophil-activation test based upon the expression of CD63 (gp53) in the presence of allergens. It is an effective diagnostic test for pollen-allergic patients. However, it is not known whether Basotest results differ during the pollen season. METHODS: We examined the activation of basophils by Basotest in 13 patients sensitized only to grass pollen, before and during the pollen season, in order to assess whether Basotest could be used as a diagnostic test during the pollen season. Dose-response curves with 10-fold increasing concentrations of timothy grass pollen (10-4 to 100 AU) were carried out. RESULTS: Basophils were not activated spontaneously during the pollen season since the CD63 expression was below detectable levels before in vitro cell activation. A decreased percentage of activated basophils at the peak of activation was found in comparing the pre- and in-season tests, but all patients had a positive test. When basophil activation was at its peak, the allergen concentration was similar during the two periods. Moreover, the median area under the curve was significantly (P < 0.02) reduced during the season as compared to before the season. CONCLUSION: Basotest can therefore be used as a diagnostic test during the pollen season, but the allergen exposure needs to be characterized if quantitative studies are performed.

Adult↗
PubMed2001

Seasonal differences of peak expiratory flow rate variability and mediators of allergic inflammation in non-atopic adolescents.

Variations in peak expiratory flow (PEF) and serum eosinophil mediators were studied in healthy adolescents. Twenty-five boys and 31 girls, 11-16 years of age (mean age 14.3 years), were selected and investigated during the birch pollen season of 1995; 45 were also investigated during the autumn of the same year. The PEF was measured twice daily and eosinophil mediators in serum and in urine were measured by radioimmunoassay (RIA) once during the birch pollen season and once in autumn. The type values of the daily PEF variation, expressed in amplitude percentage mean, were 6.4 and 3.9%, mean values were 7.35 and 6.74%, and the 95th percentiles were 18 and 14%, during the birch pollen season and autumn, respectively. The 95th percentiles were 41 and 38 microg/l for serum eosinophil cationic protein (s-ECP), 74 and 62 microg/l for serum eosinophil protein X (s-EPX), 987 and 569 microg/l for serum myeloperoxidase (s-MPO), and 165 and 104 microg/mmol for urinary eosinophil protein X/urinary creatinine (u-EPX/u-creatinine), during the birch pollen season and autumn, respectively. The levels of the eosinophil mediators decreased significantly from May (n = 56) to November (n = 45), for s-ECP from a median value of 14 microg/l to 7 microg/l (p= 0.001), for s-EPX from a median value of 28 microg/l to 20 microg/l (p= 0.001), and for the neutrophil mediator, s-MPO, from a median value of 440 g/l to 292 g/l (p< 0.001). The PEF variability decreased significantly (p= 0.037), from spring (n = 55; median 8%, 95% confidence interval [CI] 7.8-10.19) to autumn (n = 44; median 6%, 95% CI 6.1-8.9). A significant correlation was found between the levels of s-ECP and s-EPX (rs = 0.7, p< 0.001), between s-ECP and s-MPO (rs = 0.6, p< 0.001), between s-EPX and s-MPO (rs = 0.4, p< 0.005), and between s-EPX and u-EPX/u-creatinine (rs = 0.6, p< 0.0001), in the birch pollen season (n = 56) and in the autumn (n = 45). There was a positive correlation found in PEF variability between the two seasons (n = 43; rs = 0.5, p= 0.0006). No other correlation was found between PEF variability and any other parameters. The difference in the levels of eosinophil mediators between seasons in non-atopic, healthy children is unexplained. Normal limits for mediators were higher and PEF variability was almost the same as has been reported in adults. When using normal values, seasonal influences should be considered.

Adolescent↗
PubMed1998

Seasonal variation of endogenous uveitis in south-western Finland.

PURPOSE: To evaluate if there is a seasonal pattern to the incidence of endogenous uveitis in south-western Finland with special reference to acute anterior uveitis. METHODS: The incidence rates per month of the 414 new uveitis cases from years 1980-82 and 1988 in the district of Turku University Hospital were calculated. The months of the year were grouped into warm (June to September), transitional (April, May, October, November), and cold (December to March) seasons based on the mean air temperature of the months in Turku. RESULTS: We observed a statistically significant increase in the incidence of all uveitis cases in the warm and transitional seasons compared with the cold season (p=0.030 and p=0.008 respectively). A similar seasonal trend was found among anterior uveitis cases, but not among the intermediate, posterior or panuveitis cases. The incidence of acute anterior uveitis cases was higher in the transitional than in the cold season (p=0.025). No seasonal variation of the incidence was found in the subgroup of acute anterior uveitis where ankylosing spondylitis had been confirmed (p=0.70). CONCLUSION: The present data suggests that there is seasonal variation of the incidence of uveitis in south-western Finland.

Acute Disease↗
PubMed2003

Climatic variables are associated with seasonal acute asthma admissions to accident and emergency room facilities in Trinidad, West Indies.

OBJECTIVES: To determine if there is seasonal variation in acute asthmatic visits to accident and emergency (A&E) facilities in Trinidad and to identify the climatic variables associated with such visits. DESIGN AND METHODS: A retrospective census of patients with asthma, defined as those who required emergency bronchodilator nebulization, was taken at two A&E facilities in Trinidad from 1 January 1997 to 31 December 1999. The study included patients aged 64 years and under. Patient demographic data were obtained from the A&E records. Climate variables were taken from the island's sole Meteorological Office. Multiple regression was used to identify climate variables that were independent predictors of A&E asthma visits. RESULTS: There were a total of 45 842 asthma admissions to the two facilities during the study period. Visits exhibited a cyclic pattern over the 3 years that varied according to the island's dry (January-May) and wet (June-December) seasons. There were more visits during the wet season than the dry (40 [SD=2] vs. 32 [SD=2] visits/day; P<0.001). The results of multiple regression indicated that season (P<0.001), barometric pressure (P<0.001), temperature difference (P<0.001), minimum temperature2 (P<0.001) and wind speed2 (P=0.032) were predictors of paediatric visits. Independent predictors of adult visits were season (P<0.001), relative humidity (P<0.001), minimum temperature (P=0.01), temperature difference2 (P<0.001) and minimum temperature2 (P=0.004). Season and climatic variables explained 18% of the variance of the total A&E asthma admissions. CONCLUSION: There is seasonal variation in acute asthma visits to A&E facilities in Trinidad, which remains significant after controlling for climate variables. However, while climate has a role, there are other factors that may also be responsible for increased visits during the wet season. More research is needed to identify these factors.

Acute Disease↗
PubMed2003

Leptin and seasonal mammals.

Seasonal mammals commonly exhibit robust annual cycles of adiposity, food intake and energy metabolism. These cycles are driven by changes in the external daylength signal, which generates a diurnal melatonin profile and acts on neuroendocrine pathways. The white adipose tissue hormone leptin reflects overall adiposity in seasonal mammals, and consequently undergoes significant seasonal fluctuations in secretion. The seasonally breeding Siberian (Djungarian) hamster is a convenient laboratory model to study the effect of a seasonal time-keeping clock on energy metabolism, appetite regulation and the control of adiposity. We have shown that administration of exogenous leptin at physiological doses induces significant loss of adipose tissue for short-day housed winter-like hamsters in which endogenous adipose tissue and leptin concentrations are already low. By contrast, long-day housed hamsters with high adipose tissue reserves are refractory to the effects of leptin. This phenomenon of seasonal leptin resistance appears to be a general feature of other seasonally breeding mammals, and may reflect the operation of an annual timer controlling leptin uptake and/or action on central nervous system signal transduction pathways. The mobilization of fat by leptin in short-day housed hamsters is not associated with changes in expression in either anorexic or anabolic peptides expressed in leptin-receptor rich structures in the arcuate region of the hypothalamus, and suggests that leptin may target other structures. These data contrast with studies, which show that homeostatic mechanisms in response to feed-restriction induce changes in hypothalamic peptides in a similar manner to nonphotoperiodic species. Thus, the long-term seasonal regulation of body weight set point and leptin feedback may operate through separate pathways to those responsible for acute responses to food restriction.

Adipose Tissue↗
PubMed2001

Seasonality of birth for cancer in Northern England, UK.

Environmental factors operating around the time of birth may influence the subsequent development of childhood cancer, particularly leukaemia. Certain factors may vary with season (e.g. infections), and we therefore investigated whether there was any evidence of seasonality of month of birth, based on data from 4199 children diagnosed with cancer under the age of 15 years. We extracted details of (i) children born 1960-95 and diagnosed 1968-95 from two population-based registries, covering the Northern (n = 2053) and Yorkshire (n = 1977) Regional Health Authority and (ii) children born in Cumbria 1950-93 and diagnosed anywhere in the UK before 1994 from a birth cohort database (n = 397). The following diagnostic categories were analysed: 0-14 years--all cancers, leukaemias, acute lymphoblastic leukaemias, central nervous system tumours, all other solid tumours; 1-6 years--leukaemias, acute lymphoblastic leukaemias. Seasonal variation was tested using Walter and Elwood's test, and logistic regression analysis allowing for cyclical variation in month of birth. No evidence of seasonality was present for any group except acute lymphoblastic leukaemia diagnosed among 1- to 6-year-olds. Seasonal trends varied by region: in the Northern and Cumbrian datasets, seasonality patterns were significant and similar (P < 0.05) with a predicted peak in early spring, whereas in Yorkshire there was less strong evidence of seasonality (P = 0.08) with a peak predicted in late summer. These findings suggest that local seasonal environmental factors operating around the time of birth are not associated with the totality of childhood cancer, but possible links with acute lymphoblastic leukaemia are supportive of a hypothesis of an infectious aetiology.

Adolescent↗
PubMed2004

Montelukast plus cetirizine in the prophylactic treatment of seasonal allergic rhinitis: influence on clinical symptoms and nasal allergic inflammation.

BACKGROUND: The aim of our study was to investigate effects of 6-week pretreatment of seasonal allergic rhinitis (AR) with cetirizine, and montelukast, alone and in combination. Antihistamine/antileukotriene treatment is effective in AR. Antihistamines may prevent AR symptoms while prophylactic activity of antileukotrienes remains unclear. METHODS: Sixty AR patients, aged 18-35 years, were randomized to receive placebo, montelukast only, cetirizine only, or montelukast plus cetirizine, 6 weeks prior and 6 weeks after the beginning of grass pollen season. Mean self-recorded in-season symptom scores and mean weekly all-symptom scores were analyzed. In 31 patients, nasal lavages were performed before treatment, and at the end of the study, i.e. 12 weeks after the treatment initiation. Eosinophil and basophil counts, eosinophil cationic protein (ECP), and mast cell tryptase (MCT) levels were evaluated in lavage samples. RESULTS: Combined montelukast/cetirizine pretreatment significantly reduced in-season symptom score for sneezing, eye itching, nasal itching, rhinorrhea, and congestion. Montelukast plus cetirizine were more effective than cetirizine alone in preventing eye itching, rhinorrhea, and nasal itching. Moreover, combined pretreatment with montelukast and cetirizine delayed appearance of AR symptoms. Eosinophil nasal lavage fluid counts were significantly increased during pollen season in placebo and montelukast-only groups. No differences were observed in basophil counts. The in-season ECP level was significantly increased in all groups except montelukast-plus-cetirizine group. In-season MCT levels were not increased. CONCLUSION: Combined antihistamine and antileukotriene treatment started 6 weeks before the pollen season is effective in preventing AR symptoms and reduces allergic inflammation in nasal mucosa during natural allergen exposure.

Acetates↗