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PubMed1984

Seasonal variation of febrile convulsion in Japan.

The 6-year incidence rates of febrile convulsions in all 3-year-old children in Fuchu (covering 95% of children, number examined 17,044) was 8.2%. The incidence was higher in boys than in girls (9.0%: 7.5%, P less than 0.001). The incidence rates varied with the month and year of birth, but the variations observed were slight. Two peak appearances of seasonal variation of the first febrile convulsion were found in November-January and in June-August. The former could be interpreted as a tendency to winter virus infection of the upper respiratory tract in children. The other peak in summer could be explained as a tendency to gastrointestinal infection. Liability to febrile convulsion was influenced by the age of children and by the seasonal variations of febrile illness, but not by the season of birth.

Age Factors↗
PubMed1993

Seasonal variation in immediate skin test reactions.

Seasonal variation in the size of immediate prick skin tests was examined in relation to changes in seasonal pollen exposure. Immediate skin test reactions to serial 5-fold dilutions of: (1) a specific pollen during its season (short ragweed), (2) a specific pollen from an earlier season (tree), (3) a perennial allergen (D farinae, D pteronyssinus, or cat), and (4) histamine were examined at the projected trough of ragweed-specific IgE (2nd week in July), at the peak ragweed pollen count (3rd week August), at the estimated peak in ragweed-specific IgE (4th week in September) and at a time of no pollen exposure (2nd week in February). All 30 subjects had symptoms of rhinitis during the ragweed season and a 3 mm or greater wheal to: 100,000 AU/mL of short ragweed, 1:20 wt/vol of a tree exact, and a perennial allergen either 100,000 AU/mL of cat or 10,000 AU/mL of D farinae or D pteronyssinus. The median equivalent dose (dose of skin test material required to produce the median skin test index score) for the four time periods revealed significant seasonal differences. The reactions in October and February were significantly greater than those in July and August for all skin test agents. Histamine, ragweed, and trees showed maximal sensitivity in October, while perennial allergens demonstrated a peak in skin test sensitivity during mid-February.

Adult↗
PubMed1985

Seasonal variations in the muscarinic regulation of acetylcholine release from Torpedo electric organ nerve terminals.

The cholinergic nerve endings of the electric organs of Torpedo ocellata contains presynaptic muscarinic acetylcholine receptors (mAChR) which regulate acetylcholine (ACh) release by negative feedback. The efficiency of this muscarinic regulation varies circannually: maximal inhibition is observed in the winter, much smaller effects in the fall and spring, and no effect is observed during the summer. These variations are accompanied by seasonal changes in the ability of the mAChR to trigger the synthesis of its second messenger (a prostaglandin E-like substance) and in the ability of exogenous prostaglandin E2 to inhibit ACh release. No seasonal changes were found in the number of presynaptic mAChRs. These findings suggest that the observed seasonal variations are due to changes in both the metabolism of prostaglandins in the electric organ and the sensitivity of the ACh-releasing apparatus to the muscarinic second messenger.

Acetylcholine↗
PubMedDate not supplied

Seasonal variation in suicide in a predominantly Caucasian tropical/subtropical region of Australia.

Seasonal variations in suicide were examined in a Caucasian population living relatively close to the equator. A spring/early summer peak, but no secondary autumn peak, was found for males. An autumn trough was found for females. No significant seasonal variation was found for rurality, distance from the equator, employment status, or methods of suicide. Post-mortem blood alcohol levels were higher in spring and summer, possibly reflecting socialization patterns. The modest associations are consistent with suggestion that climatic influences may produce greater variation in suicide rates where the climatic variation itself is greater.

Australia↗
PubMed2001

Three forms of GnRH in the brain and pituitary of the turbot, Scophthalmus maximus: immunological characterization and seasonal variation.

Three forms of GnRH, chicken (c) GnRH-II, salmon (s) and seabream (sb) GnRH, were immunologically characterized in the brain and pituitary of turbot by ELISA. cGnRH-II and sGnRH were detected in the brain, while sbGnRH and sGnRH (but not cGnRH-II) were detected in the pituitary. In females, the levels of cGnRH-II in the turbot brain extracts increased from May to July, concomitant with an increase in oocyte diameter. In the pituitary, sbGnRH was found to be the dominant form, with levels 100-600-fold those of sGnRH. Both sGnRH and sbGnRH in the pituitary showed variation during the spawning season; sbGnRH increased from May to July and correlated with the increase in oocyte diameter, while sGnRH decreased. The overall patterns were the same for male turbot, although levels were generally lower. These findings suggest that sbGnRH could be controlling reproduction in the turbot. However, the seasonal variation in sGnRH indicates a potential physiological role in turbot reproduction. This study gives the first immunological indications that sbGnRH is present in the pituitary of a pleuronectiform fish, and will provide the basis for further studies on the endocrine regulation of reproduction in flatfish.

Animals↗
PubMed2003

Hair zinc concentrations not subject to seasonal variation in adults in New Zealand.

The analysis of recently grown hair for zinc provides a biomarker of recent zinc status. Seasonal variation of zinc in hair has been demonstrated in children. The aim of this study was to investigate whether on a month-by- month basis there is a seasonal variation in hair zinc concentration in an apparently well-nourished adult population in New Zealand. It was hypothesized that increased hours of daylight would be associated with an increase in zinc concentration in hair. Thirty-four subjects (20 F, 14 M) aged 18-54 yr had occipital hair sampled at monthly intervals between June and December. Food variety was assessed by questionnaire. After thorough washing of the hair followed by nitric acid digestion, zinc was determined by flame atomic absorption spectrometry (FAAS) with special attention to the inclusion of blanks, internal and international standards, and reduction of contamination in each sample run. Analyses between two laboratories confirmed that two FAAS instruments were giving the same reading. No seasonal variation in hair zinc concentration was found. Reported dietary variety, ethnicity, gender, and hair color were unrelated to hair zinc concentrations in this population. This study adds to evidence that will help define the role of hair zinc in determining recent zinc status.

Adult↗
PubMedDate not supplied

Seasonal variation of cortisol plasma levels in depressives.

There is some evidence for a seasonal variation of plasma cortisol levels after administration of dexamethasone in depressed subjects. This variation is suspected to be associated with similar season-related changes in pre-dexamethasone cortisol levels. Therefore, cortisol plasma levels in depressed subjects before and after dexamethasone administration were investigated. No seasonal variation was found in pre- or post-dexamethasone cortisol levels.

Adult↗
PubMed2002

The incidence and seasonal variations of acute primary angle-closure glaucoma.

The incidence and seasonal variations of acute primary angle-closure glaucoma (APACG) was studied. It was based on a retrospective chart review of 121 hospital patients in Split, Croatia for the fifteen-year period from 1985 through 1999. The average incidence was 4.1 cases per 100,000 per year in the total population and 7.1 per 100,000 in those aged 30 years and older. APACG affects women almost twice more often than men. The incidence rate increased with age. No seasonal variations in the occurrence of APACG and no correlation with the mean duration of light exposure per season were found.

Acute Disease↗
PubMed1982

Seasonal variations in scrotal circumference, sperm quality, and sexual ability in rams.

Seasonal variations in scrotal circumference, spermatozoal motility, morphologically normal spermatozoa, libido, and serving capacity were studied in Suffolk, Lincoln, Columbia, and Polypay rams (5 of each breed). There were marked seasonal variations in the scrotal circumference, morphologically normal spermatozoa, libido, and serving capacity for each of the breed types. Mean scrotal circumference was highest from August through October and lowest in February. Spermatozoa that were morphologically normal were highest in proportion in September (82.3%) and lowest in proportion in February (57.8%). Libido and serving capacity scores were highest from September through November and lowest in March.

Animals↗
PubMed1997

Geographic and seasonal variation in Mycobacterium avium bacteremia among North American patients with AIDS.

Analysis of geographic risk was performed for Mycobacterium avium complex (MAC) bacteremia among North American patients with AIDS. Monthly mycobacterial blood cultures were taken from patients who were placebo recipients in a prospective evaluation of MAC prophylaxis. Of 571 patients, 102 (17.9%) acquired MAC bacteremia during an average follow-up of 256 days. The area with the highest risk for MAC was the South Central region (27.9%; P < 0.02), whereas the area with the lowest risk was Canada (11.3%; P = 0.12). When the southern states were combined and compared with the northern states and Canada, the incidence of MAC bacteremia was higher in the southern states (21.6% versus 14.0%, P < 0.03). Proportional hazards analysis was performed for the difference between the North and South and controlled for baseline CD4 cell count. In this analysis, time to MAC was significantly longer in the North (hazard ratio = 0.587, 95% confidence interval 0.390 to 0.883, P = 0.01). Although overall variation in seasonality was not marked, there was a significant decrease in cases in the North during the summer months (P < 0.01). We conclude that geographic location is a risk factor for MAC bacteremia in patients with advanced AIDS, with decreased risk in northern North America.

AIDS-Related Opportunistic Infections↗
PubMed2005

Seasonal variation in undiagnosed HIV infection on the general medicine and trauma services of two urban hospitals.

OBJECTIVE: To examine the seroprevalence of undiagnosed HIV and variation by season among patients admitted to the general internal medicine (GIM) and trauma services of two urban hospitals. DESIGN: A cross-sectional blinded HIV-1 seroprevalence survey. SETTING: A 725-bed academic medical center's hospital and an affiliated 324-bed tertiary care hospital. PARTICIPANTS: Residual serological specimens were obtained for unique patients aged 17 to 65 to study services in summer (June 16 to September 4, 2001) and fall to winter (November 1, 2001 to January 8, 2002). METHODS: Hospital files provided data on demographics, service type, and discharge clinical categories (fall-winter group only). HIV ELISA (enzyme-linked immunosorbent assay) tests with confirmatory Western blot were linked to subjects' de-identified files. We excluded 34 subjects with known HIV. Of the remaining unique admissions in summer (n=604) and fall-winter (n=978), 60% and 55% were tested, respectively. Predictors of undiagnosed HIV infection were examined using multivariate analysis. RESULTS: The summer cohort (n=362) had significantly lower unadjusted seroprevalence of undiagnosed HIV infection (1.4%; 95% confidence interval [CI], 0.4% to 3.2%) than the fall-winter cohort (n=539; 3.7%; 95% CI, 2.3% to 5.7%; P=.04). Overall, undiagnosed HIV was somewhat less likely in women (adjusted odds ratio [AOR], 0.45; 95% CI, 0.19 to 1.07) but more likely in black patients (AOR, 3.46; 95% CI, 0.70 to 17.06). In the fall-winter cohort, undiagnosed HIV was more likely for discharges with the following clinical categories versus those with a cardiac condition: dermatologic/breast (AOR, 14.90; 95% CI, 1.20 to 184.77), renal/urological (AOR, 22.43; 95% CI, 2.12 to 236.75), or infectious (AOR, 31.08; 95% CI, 2.40 to 402.98). CONCLUSIONS: The higher seroprevalence of undiagnosed HIV in the fall-winter admissions to GIM and trauma services supports especially targeting HIV testing in these months.

Adolescent↗
PubMed2000

Time-dependent decrease and seasonal variation of the porosity of recently erupted sound dental enamel in vivo.

Recently erupted teeth are more sensitive to dental caries than teeth that have remained free from caries lesions for a few years after eruption. It has been hypothesized that this may be ascribed to differences in enamel porosity. The objective of the present work was to assess the time-dependence of electrical conductance, as an indication of porosity, of occlusal enamel in recently erupted permanent molar teeth. Fifty children aged 5-15 years of age, receiving regular dental care at six-month intervals, participated in the study when their first molar teeth (in 5- to 6-year-olds) or their second molar teeth (in 11- to 15-year-olds) had not been exposed to the oral environment for more than six months. On the first semi-annual check-up after eruption of a first or second molar, baseline diagnostic measurements, i.e., visual inspection and electrical conductance measurements (ECMs), were made at three or four pre-defined sites in the fissures. Subsequently, data collection was repeated every six months for three years. Sites were excluded from ECMs when a caries lesion was observed at a site by visual inspection. After 36 months, there were 257 sites in teeth considered sound upon visual examination. The ECM values of these sound sites showed a clear decrease with time after the first examination. The conductance decreased on average from 0.13 (Momega)(-1) to 0.059 (Momega)(-1). Since the conductance is assumed to be proportional to the porosity of the enamel, the latter decreased by a factor of 2.2 over the 36-month period. The results furthermore indicated a higher conductance for maxillary than for mandibular enamel. Almost all sites in that sample appeared to be in teeth that were observed for the first time during the months September to December. Electrical conductance, and therefore enamel porosity, of the sites showed a periodic variation with season of observation: In the fall, the conductance was higher than in the spring. This implies that a dentist should be more prudent in the fall than in the spring when indicating restorative treatment of an incipient caries lesion.

Adolescent↗
PubMed1994

Seasonal variations of plasma fibrinogen and factor VII activity in the elderly: winter infections and death from cardiovascular disease.

There are approximately 20,000 excess deaths from cardiovascular disease each winter in England and Wales. The reasons for the excess have not been fully elucidated. For one year, we studied 96 men and women aged 65-74 living in their own homes in order to examine seasonal variation in plasma fibrinogen and factor VII clotting activity (FVIIc), and to investigate relationships with infection and other cardiovascular-disease risk factors. Both fibrinogen and FVIIc plasma values were greater in winter with estimated winter-summer differences (confidence intervals) of 0.13 (0.05-0.20) g/L for fibrinogen and 4.2 (1.2-7.1)% of standard for FVIIc. These differences could account for 15% and 9% increases in ischaemic heart disease risk in winter respectively. After adjustment for confounding by season, fibrinogen was strongly related to neutrophil count (p < 0.0001), C-reactive protein (p < 0.0001), alpha 1-antichymotrypsin (p < 0.0001), and self-reported cough (p < 0.0001) and coryza (p = 0.0004), but not to ambient temperature. Therefore, we suggest that seasonal variation in fibrinogen might be induced by winter respiratory infections via activation of the acute phase response. Seasonal variations in the cardiovascular risk factors fibrinogen and FVIIc provide further possible explanations for the marked seasonal variation in death from ischaemic heart disease and stroke in the elderly.

Acute-Phase Proteins↗
PubMed2000

Seasonal variation of HbA1c in intensive treatment of children with type 1 diabetes.

OBJECTIVE: The aim of this study was to measure whether there is a seasonal variation in glycosylated haemoglobin concentrations and insulin dose used in the intensive treatment of children with type 1 diabetes, and whether such variation is related to severe hypoglycaemia. PATIENTS: A geographic population of 114 intensively treated type 1 diabetic patients < 19 years of age, mean 12.7 (SD 4.3) years, with diabetes onset before 1995, were studied in a cohort 1995-96. METHODS: HbA1c, insulin doses and severe hypoglycaemia were registered at regular visits scheduled quarterly, but not standardised in time. Seasonal mean values were calculated for HbA1c and insulin dose. RESULTS: Lower HbA1c was seen in spring and summer, and higher in autumn and winter (p=0.023). Patients reporting severe hypoglycaemia had a seasonal variation in HbA1c (p=0.019) and a tendency to seasonal variation in insulin dose, while patients not reporting severe hypoglycaemia did not vary in HbA1c or insulin dose. CONCLUSIONS: Self-control and adjustment of insulin doses to seasonal change need to be improved also in intensively treated children, with regard to the risk for worsened metabolic control after the summer and increased severe hypoglycaemia in spring and early summer. The findings have important implications for design of short-term studies of metabolic control.

Adolescent↗
PubMedDate not supplied

[Seasonal variations in dexamethasone suppression test in psychiatric patients].

The existence of seasonal variations in the dexamethasone suppression test (D.S.T.) has been remarked. In a sample of 345 patients with affective symptomatology and various psychiatric diagnostics, patient with major depression have higher non suppression levels in spring and winter; a similar but stronger seasonal variations is observed in patients with melancholic and patients with psychotic syndrome showed a similar tendency. In patients with diagnostics different from depression (dementia, schizophrenia, mania, anxiety disorders), the non suppression level is higher in winter. Some similarities with the contributions of other authors are observed but in general disagreements are more frequent, which suggests us the influence of latitude and geo-climatic changes, since the seasonal variability can not be explained by means of seasonal changes in demographic or clinical variables, as diagnostic or psychiatric syndrome.

Adolescent↗
PubMed2002

Seasonal variation and background levels of heavy metals in two green seaweeds.

Seasonal variation in the contents of different metals (Al, Cr, Cu, Fe, Mn, Ni and Zn) in two genera of macroalgae, Ulva and Enteromorpha was studied at 22 sites on the northwest coast of Spain. The seasonal variation in the different metals followed a similar pattern in both seaweeds and appeared to be caused by dilution during the period of maximum growth and concentration during periods of slow growth. Fluvial inputs of Al, Fe and Mn in autumn and winter appeared to accentuate the latter effect: the concentrations of these three metals in both macroalgae and of Cr in Enteromorpha were highest at those sites most influenced by inputs from rivers. The background levels of Cr, Cu, Ni and Zn in the algae in summer and winter were established.

Chlorophyta↗
PubMed2000

Seasonal variation of risk factors for cardiovascular disease and diet in older adults.

We have already published much of our data on the seasonal variation of cardiovascular disease risk factors in a cohort of 65-74 year old men and women living in Cambridge, UK. In this paper we give a concise overview of our findings and include previously unpublished data relating to diet. Seasonal variation in intake of fat, copper, beta-carotene and vitamins A, C and E were all found with increased fat, beta-carotene and vitamin A intakes in autumn and winter while vitamin C and E intakes peaked in summer. Seasonal variation of vitamin C intake and serum ascorbate concentrations were particularly pronounced. We postulate that low vitamin C levels in winter could be associated raised plasma fibrinogen and plasminogen activator-1 (PAI-1) concentrations and therefore with increased cardiovascular risk.

Aged↗
PubMed1999

Expression of three distinct somatostatin messenger ribonucleic acids (mRNAs) in goldfish brain: characterization of the complementary deoxyribonucleic acids, distribution and seasonal variation of the mRNAs, and action of a somatostatin-14 variant.

In this study, three somatostatin (SRIF) complementary DNAs (cDNAs) were characterized from goldfish brain. The cDNAs encode three distinct preprosomatostatins (PSS), designated as PSS-I, PSS-II, and PSS-III. The goldfish PSS-I, PSS-II, and PSS-III contain enzymatic cleavage recognition sites, potentially yielding SRIF-14 with sequence identical to mammalian SRIF-14, SRIF-28 with [Glu1, Tyr7, Gly10]SRIF-14 at its C-terminus, and [Pro2]SRIF-14, respectively. The brain distribution of the three SRIF messenger RNAs (mRNAs) were differential but overlapping in the telencephalon, hypothalamus and optic tectum-thalamus regions. Seasonal variations in the levels of the three mRNAs were observed, with differential patterns between the three mRNAs and differences between the sexes. However, only the seasonal alteration in the levels of the mRNA encoding PSS-I showed close association with the seasonal variation in brain contents of immunoreactive SRIF-14 and inversely correlated with the seasonal variation in serum GH levels described in the previous studies, suggesting that SRIF-14 is involved in the control of the seasonal variation in serum GH levels. The putative SRIF-14 variant, [Pro2]SRIF-14, inhibited basal GH secretion from in vitro perifused goldfish pituitary fragments, with similar potency to SRIF-14; [Pro2]SRIF-14 also inhibited stimulated GH release from the pituitary fragments, supporting that [Pro2] SRIF-14 is a biologically active form of SRIF in goldfish.

Amino Acid Sequence↗