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PubMedDate not supplied

Seasonal variations in the kinetics of bupivacaine in the mouse.

Very few studies have been devoted to the influence of the time of the year, i.e. seasonal variations, on drug kinetics. This study aims to evaluate whether or not the kinetics of bupivacaine varied according to the time of the year in mice. Eight groups of 30 animals each received bupivacaine (20 mg/kg i.p.) at a specific month of the year, i.e. February (second week), March (first week), May (fourth week), July (first week), September (fourth week), November (second and third weeks) and December (first week), at the same time of the day (10.00 h). Total bupivacaine serum concentrations were determined by using a specific gas liquid chromatographic method on blood samples collected by decapitation at 0.25, 0.5, 1, 2, 4 and 6 h after drug administration. Pharmacokinetic variables were determined, according to a non linear fitting method (two compartment open model). All data were compared by ANOVA and the influence of the month of the year was estimated by Cosinor analysis. According to the month of the year, the kinetic parameters were significantly different except for Vd: the maximal Cmax occurred in July, the highest Tmax occurred in May, the maximal T1/2 beta and the maximal AUC were observed in February. The mechanisms underlying these variations may depend on seasonal variations of resorption, distribution, metabolism and elimination.

Analysis of Variance↗
PubMed2005

Seasonal variation in the occurrence of cutaneous melanoma in Europe: influence of latitude. An analysis using the EUROCARE group of registries.

The aim of our study was to analyse seasonal variations in melanoma incidence in Europe. Data from 28117 cutaneous melanoma cases reported during 1978-1993 to the EUROCARE group of registries were analysed. There is a clear summer peak in incidence in Western countries (summer-winter ratio: 1.31 P < 0.0001; Nam's test), which was not observed in Central Europe (ratio: 1.06; P = 0.0699). The amplitude of seasonality is higher for females (ratio = 1.38, 95% Confidence Interval (CI) [1.31-1.44]) than for males (ratio = 1.21 95%CI [1.14-1.29]). It is also higher for upper and lower limbs (1.44 and 1.46, respectively), than for head and neck or trunk regions (1.09 and 1.20, respectively). The amplitude of seasonality also varies with latitude and increases with time: in a linear regression adjusting for age, gender and anatomical localisation, the date of diagnosis was significantly closer to summer solstice with decreasing latitude (P = 0.0005) and for more recent year of diagnosis (P = 0.0123). The effect of latitude on the amplitude of the seasonal variation in melanoma incidence in Europe may be an indicator of ultraviolet B (UVB) exposure. Furthermore, an increase in intentional sun exposure could lead to an increase in melanoma promotion and thus to an increase in the amplitude of seasonal variation.

Europe↗
PubMed1990

Monthly and seasonal variations in the frequency of congenital anomalies.

Three large and comparable series of births were used to test the working hypothesis that if there is a real seasonal variation in the frequency of a given congenital malformation; it would have to be shown by adequate analysis; to be more overt in non-tropical areas; and to be six months out of phase in northern and southern hemispheres. The data set were hospital births from tropical (287,165 births) and non-tropical (582,585 births) South America, and from Italy (508,536 births). Sixteen well-defined malformation types were tested: anencephaly, spina bifida, cephalocoele, hydrocephaly, microtia, cleft palate, cleft lip, oesophageal atresia, anal atresia, hypospadias, pes equino-varus, pes talovalgus, postaxial polydactylyl, pre-axial polydactylyl, diaphragmatic hernia, and Down's syndrome. No seasonal variation was proven (p less than 0.01) for any malformation type in any of the three series of data by means of Walter and Elwood's test, or Hewitt et al's non-parametric test2 applied to seven instances with sample sizes smaller than 50 cases. Variations of borderline significance (p less than 0.05) included oesophageal atresia in tropical South America, none in non-tropical South America, and anencephaly in Italy. It is concluded that seasonal variation in the occurrence of congenital malformations is a rare phenomenon when tests are strictly used within their recommended limitations.

Congenital Abnormalities↗
PubMed1986

The seasonal variation of total body calcium.

Total body calcium was measured using in vivo neutron activation analysis in 156 patients with rheumatic diseases at six-month intervals. Evidence of seasonal variation was sought by relating deviation from a linear change to the month in which the measurement was made. A cyclic regression fitted to the data had an amplitude of 0.25% but a significance of only P = 0.08. The calcium balance studies of Malm were re-analysed to quantify the seasonal variation he had demonstrated in one group of men. The deduced variations of body calcium were highly significant, with a phase and amplitude very similar to the regression of our data. Both analyses differed from two previous reports of seasonal variations of part-body bone mineral of much greater amplitude and different phase.

Calcium↗
PubMed2000

Electrical impedance measurements at different skin sites related to seasonal variations.

BACKGROUND/AIMS: In a previous study we mapped differences in electrical impedance between different anatomical locations related to age and sex. Now we employ the electrical impedance technique for studying the seasonal variations for the same skin sites. METHOD: The investigation was performed on 48 healthy volunteers divided into two groups on the basis of sex. Readings of electrical impedance were taken from ten different body locations at each of the four seasons during one year. Electrical impedance spectra were measured in the frequency range 1 kHz to 1 MHz, and four impedance indices based on the complex impedance values at 20 kHz and 500 kHz were calculated. RESULTS: The baseline values varied from one site to another and increased significantly for most sites from the winter to the summer, while the changes from October to March were negligible. Using ANOVA, the seasonal variation was found to be a more important factor than sex. CONCLUSIONS: Our results suggest that seasonal variations for different skin sites should be taken into consideration when using the electrical impedance technique.

Journal Article↗
PubMed1993

Time trends and seasonal variation in hospital admissions for childhood asthma in the Athens region of Greece: 1978-88.

BACKGROUND: The aim of the study was to determine the trend and seasonal variation in hospital admissions for childhood asthma in the Athens region of Greece. METHODS: Data were obtained from hospital registries of the three main children's hospitals in Athens between 1978 and 1988. Children admitted with the diagnosis of asthma, asthmatic bronchitis, or wheezy bronchitis were included. The data were expressed as admission rates per 100,000 of the same aged population. RESULTS: There were 9795 admissions for asthma over the 11 years and the admission rate rose by 294%. Admissions among those aged 0-4 and 5-14 rose by 272% and 379% respectively. Monthly admissions showed a pronounced seasonal variation, rising during the cold damp period in the 0-4 age group, but peaking around May in the 5-14 age group. CONCLUSIONS: These findings suggest that hospital admissions due to asthma in the Athens region have increased considerably since 1978, and that clear cut seasonal variations exist which are specific to age.

Adolescent↗
PubMed2001

Seasonal variation of acute necrotising ulcerative gingivitis in South Africans.

OBJECTIVES: To examine seasonal variations in the presentation of acute necrotising ulcerative gingivitis (ANUG) in a previously unstudied population in Cape Town, South Africa. DESIGN: A descriptive study of all presenting cases of ANUG at a health center over 6 years; patients were examined at one point in time. SETTING: A clinic-based cross-sectional study was carried out among patients presenting routinely to the oral medicine clinic at the University of the Western Cape. Patients at this clinic were mostly colored and black people, and were of low socioeconomic status. SUBJECTS AND METHODS: All patients presenting to the periodontal clinic were examined during the period from 15 March 1992 to 15 March 1998 and interviews were conducted. A comprehensive clinical intra-oral and peri-oral examination was carried out using a dental mirror and blunt probe by three trained calibrated dental examiners. The minimum criteria for inclusion as an ANUG patient were painful, bleeding gums with irreversible destruction of the interdental papillae (cratering) and marginal gingiva. Patients with multiple small ulcerations not restricted to the gingiva, but including other oral sites such as the tongue and buccal mucosa were diagnosed as herpetic stomatitis. Other distinguishing characteristics of ANUG included presence of a pseudomembrane, odor, a strange taste in the mouth, and hypersalivation. Swabs and biopsies taken to verify the diagnosis when necessary. If there was any doubt as to the diagnosis of the lesion it was not included among the ANUG cases. MAIN OUTCOME MEASURE: Presence of ANUG. RESULTS: Among the 19944 patients presenting for periodontal treatment, 684 were found to have ANUG. The ANUG patients consisted of 58% males; 73% of the ANUG patients were between the ages of 5 to 12 years. The majority of ANUG patients presented during the summer (55.4%), 27.7% in autumn and 8.4% during both winter and spring. Significant differences were evident between the numbers seen during the different seasons. CONCLUSIONS: This study demonstrated a significant seasonal variation in the occurence of ANUG in Cape Town, South Africa.

Adolescent↗
PubMedDate not supplied

Regional, temporal, and seasonal variations in births and deaths: the effects of famines.

A knowledge of the seasonal variation in births and deaths during normal years is important for analyses of the effects of wars, famines, epidemics or similar privations on these two variables. In studies of seasonality, multiple trigonometric regression models are more flexible than the simple sine curve. The seasonal variation in mortality in Iceland, 1856-1990, shows a strong secular decrease, and a connection between this and the epidemiological transition is considered. As a consequence of the severe famine in Finland in 1867-68, the mortality for the whole year 1868 was almost four times as high as during normal years, and the seasonality of the mortality was even more accentuated. The birth rate in Finland during 1868 was about 70 percent of that during normal years and showed an aberrant seasonality, with a strong trough from October 1868 to February 1869 (fewer conceptions between January and May 1868, when the food shortage was severe).

Birth Rate↗
PubMed1984

Seasonal variations in physiological indices of adult female white-tailed deer in Texas.

Seasonal variations in blood chemistry, urine chemistry, fat reserves, and crude protein levels of rumen contents were determined for free-ranging adult female white-tailed deer (Odocoileus virginianus Zimmermann) in central Texas. Seasonal variations (P less than 0.05) existed for serum total protein, albumin, globulin, albumin/globulin ratios, blood urea nitrogen (BUN), cholesterol, alkaline phosphatase, creatinine, phosphorus, and sodium; and urinary urea/creatinine (U/C) ratios, rumen crude protein, the kidney fat index (KFI), femur marrow fat (FMF), and dressed weights. Variations in BUN, urinary U/C ratios, dressed weights, KFI, and FMF were attributed partially to the nutritional demands of late gestation and lactation.

Adipose Tissue↗
PubMed2001

Is there a seasonal variation in gonorrhea and chlamydia in adolescents?

STUDY OBJECTIVE: To determine if a seasonal variation exists in gonorrhea and chlamydia in female adolescents. DESIGN, SETTING, PARTICIPASNTS: We conducted a retrospective chart review of 604 sexually active adolescent females 21 years of age and younger in a teen pregnancy prevention clinic in a small Midwestern city. Positive gonorrhea and chlamydia tests were evaluated for seasonal variation. Chi-square, odds ratios, and 95% confidence intervals were calculated. RESULTS: A greater percentage of tests were positive in the fall than in other seasons (P = 0.028), and there was a trend towards more cases in the summer than winter and spring. CONCLUSIONS: Increased emphasis should be placed on prevention and screening during summer and fall.

Adolescent↗
PubMed2004

Effect of nasal triamcinolone acetonide on seasonal variations of bronchial hyperresponsiveness and bronchial inflammation in nonasthmatic children with seasonal allergic rhinitis.

BACKGROUND: Recent evidence suggests that patients with allergic rhinitis have lower airway inflammation and a higher prevalence of bronchial hyperresponsiveness (BHR) regardless of asthma. OBJECTIVE: To investigate markers of lower airway inflammation in nonasthmatic children with seasonal allergic rhinitis (SAR) before and during pollen season and the effect of nasal triamcinolone acetonide on seasonal variations in these parameters. METHODS: Thirty-two nonasthmatic children with SAR in response to grass and/or weed pollens were recruited and separated into 2 groups. Group 1 was treated with triamcinolone acetonide (220 microg once daily) for 6 weeks, and group 2 received no intranasal corticosteroid treatment. Bronchial responsiveness to methacholine [concentration that caused a decrease in forced expiratory volume in 1 second of 20% (PC20)], eosinophil counts in sputum and peripheral blood, and eosinophil cationic protein (ECP) levels in sputum and serum were measured before and during grass pollen season. RESULTS: Twenty-eight patients completed the study. During the pollen season, methacholine PC20 significantly decreased in both groups when compared with the corresponding preseasonal values (P = .01 and P = .003, respectively). The mean percentage of sputum eosinophils increased significantly during the pollen season compared with preseasonal values in group 1 and group 2 (12.7% +/- 2.1% vs 16.5% +/- 2.1%, P = .007, and 11.0% +/- 2.0% vs 20.2% +/- 1.4%, P = .003, respectively). Median [interquartile ranges (IQR)] sputum ECP levels were significantly higher during the pollen season when compared with the preseasonal values in group 1 and group 2 [7.5 microg/L (3.5-36.0 microg/L) vs 35.5 microg/L (13.0-71.7 microg/L), P = .04, and 18.0 microg/L (6.0-36.0 microg/L) vs 69.0 microg/L (39.0-195.0 microg/L), P = .003, respectively], as were the serum ECP levels [6.0 microg/L (2.0-13.0 microg/L) vs 19.0 microg/L (14.0-43.5 microg/L), P = .004, and 6.0 microg/L (3.0-7.0 microg/L) vs 18.0 microg/L (6.0-36.0 microg/L), P = .001, respectively]. Although the mean number of eosinophils in blood increased during the pollen season in both groups, it was only significant in group 2 (70.0 +/- 20.0 vs 161.6 +/- 29.0, P = .02). CONCLUSIONS: Although prophylactic nasal corticosteroid treatment provides significant reduction of nasal symptoms and rescue antihistamine use, there is no significant prevention in the seasonal increase of bronchial inflammation and methacholine BHR.

Adolescent↗
PubMed2005

The relationship between obesity and seasonal variation in body weight among elementary school children in Tokyo.

Typical patterns of seasonal variation in body weight among Japanese children involve increases during the fall and/or winter and decreases during the summer. However, atypical variations, namely, increases in weight during the summer, have been reported for obese children. The present study examines whether weight gain during the summer (i.e., July through September) is a possible cause of obesity. We examined seasonal changes in weight for 446 elementary school children in Tokyo in six waves between 1972 and 2004. Weight was measured monthly for 6 years in each child and was evaluated by means of time-series analysis. Overall, significant seasonal variations in weight were found in 86% of the children, most of which were typical (i.e., decreases during the summer and increases during the fall, winter, and/or early spring). On the other hand, weight gain in the summer was observed exclusively among obese children. Children whose weight increased during the summer holiday spent most of their time comfortably indoors because of air conditioners, which became popular in 1970s. A possible explanation of the observed weight gain during the summer seems to be changes in life style associated with the use of air conditioning, concomitant with insufficient physical exercise and excessive consumption of food and drink, which could disturb the rhythms of seasonal weight changes and lead to obesity.

Child↗
PubMed1985

Seasonal variations in UVR-induced DNA synthesis and in UVR inhibition of phytohaemagglutinin-stimulated proliferation of human lymphocytes.

Two years of sequential studies of the UVR (254 nm) response in normal human lymphocytes showed pronounced seasonal variations. In the winters of 1981-82 and 1982-83 the UVR-induced DNA synthesis in the lymphocytes in vitro (the DNA-repair synthesis) was very stable with inter- and intra-individual variations below 14 and 10%, respectively (15 individuals). In the summers 1982 and 1983 the inter-individual variations was 2-3-fold higher. Closer analysis revealed that this was due to a pronounced intra-individual variation with sharp fluctuations in the single individual. Also the UVR tolerance of the lymphocytes estimated by alterations of the phytohaemagglutinin (PHA) stimulated lymphocyte proliferation showed seasonal variations, being 1.5-fold higher in the winter than in the summer (P less than 0.0001, 12 individuals). The observed seasonal variations emphasize the importance of considering chronobiological variations when working with long term projects. The UVR-induced DNA synthesis was determined as the increase in incorporation of [3H]-thymidine in irradiated cells compared to non-irradiated cells after incubation for 2 h at 37 degrees C in phosphate buffered saline. The UVR tolerance was measured by the UV dose necessary for 50% reduction in PHA stimulated lymphocyte proliferation assessed after 7 days of growth.

Adult↗
PubMed1977

Seasonal variations in urinary excretion of calcium and oxalate in normal subjects in patients with idiopathic hyperclaciuria.

A longitudinal 9-year retrospective study of 24-hour urinary calcium values has been made in a metabolic stone clinic amongst patients with idiopathic hypercalciuria. No seasonal variations could be observed in contrast ot a previous study from Leeds, A prospective longitudinal study was made of 24-hour urinary calcium values in a small group of normal subjects. No seasonal variation could be ovserved. In the prospective study no seasonal variations in urinary oxalate could be observed. In a 2-year longitudinal study of stone patients with idiopathic hypercalciuria, urinary oxalate was found to be higher in the summer than in the winter. This was attributed to the combination of a higher intake of oxalate-rich foods in the summer, and the low calcium diet with which they were treated.

Calcium↗
PubMed2007

Seasonal variation of serum lipid levels in stable renal transplant recipients.

BACKGROUND/AIMS: Seasonal variation in lipid levels is well described in the general population, but has not been examined in renal transplant recipients (RTR). We sought to determine whether seasonal differences exist in RTR, a group at high risk for hyperlipidemia. METHODS: We reviewed our population of 920 adults, identifying primary allograft recipients with survival > or =1 year, stable function, and > or =1 pair of post-6 months 'winter' (December 21 to March 20) plus 'summer' (June 21 to September 22) fasting lipid measurements within the same year. Correlations between factors affecting lipids and lipid level change were followed by multiple linear regression analysis. RESULTS: 243 patients contributed 344 pairs. When most recent seasonal pair (n = 243) and all pairs (n = 344) were separately analyzed, no seasonal total cholesterol difference (winter vs. summer) was seen (5.08 vs. 5.05 mmol/l, p = 0.80; 5.11 vs. 5.09 mmol/l, p = 0.81 respectively). Opposing variation was seen between hyperlipidemic and nonhyperlipidemic patients (0.08 vs. -0.18 mmol/l for winter minus summer, p = 0.02). In multivariate analysis, seasonal cholesterol variation was predicted by level (p < 0.0001) and hemoglobin change (p = 0.01), while triglyceride variation was predicted only by level (p = 0.01). CONCLUSION: RTR do not exhibit seasonal variation in lipids, unlike the general population. Factors unique to RTR such as immunosuppressive therapies may act to suppress any seasonal effects.

Adult↗
PubMed1995

Human embryo implantation following in-vitro fertilization: is there a seasonal variation?

The purpose of this study was to determine whether there is a seasonal variation in implantation and pregnancy rates following natural cycle replacement of cryopreserved embryos. A total of 321 consecutive cycles were analysed. There were 59 pregnancies (18.4%) and 48 live births or ongoing pregnancies (15.0%). Indicator variables for each month and variables representing temporal cycles of 12, 6, 4, 3 and 2 months were related to outcome. In addition, an analysis of periodicity was performed. No temporal, clinical or demographic variable was significantly related to pregnancy. This study indicated that there was no clear seasonal variation in the pregnancy rate following natural cycle replacement. However, the power of this study was low, and it was estimated that 963 subjects would be required to detect a 10% seasonal difference in pregnancy rates.

Adult↗
PubMed2005

Seasonal variations in the nycthemeral rhythm of plasma melatonin in the camel (Camelus dromedarius).

Seasonal changes in the pattern of plasma melatonin were investigated in two groups of camels (Camelus dromedarius): 11 adult and six young camels. Animals were subjected to the outdoor conditions of a desert environment. Blood samples were taken at regular intervals of about 3 hr (added to particular samples at 1 hr before then 30 min and 1 hr after sunset, and 1 hr before and 1 hr after sunrise) for 24 hr at both solstices and equinoxes of the year. The plasma melatonin levels steeply increased soon after sunset and remained elevated throughout all the night. Then, melatonin concentrations progressively declined shortly before sunrise and returned to daytime basal levels 1 hr later. There was no seasonal variation in the amplitude or in the offset of the melatonin peak or in the daytime basal levels. The onset of the nocturnal peak was delayed by 2 hr in June at the summer solstice (P < 0.05), which can be related to the changes in night length between the two solstices. A significant effect of age was observed in all seasons. Melatonin levels were higher in the young camel group (fall equinox: P < 0.001; spring equinox: P < 0.01; winter solstice: P < 0.01; summer solstice: P < 0.05). The pattern of melatonin secretion in the camel showed a significant seasonal variation parallel to the photoperiodic changes of the year. The observed decline of melatonin levels during an extra-light pulse in the middle of the night indicates the light control of melatonin synthesis. It is not yet known if, in this low latitude desert region, the seasonal breeding period of the camel is cued by the photoperiod. The data obtained, however, clearly demonstrate that the camel has the capacity to follow and to integrate photoperiodic changes through melatonin changes.

Analysis of Variance↗
PubMed1989

Seasonal variations of plasma lipids and lipoproteins in the hedgehog, an animal model for lipoprotein (a) metabolism: relation to plasma thyroxine and testosterone levels.

We describe a study of the seasonal variations of hedgehog plasma lipids and lipoproteins and their correlation with changes in the activities of the thyroid and testis. In ten male hedgehogs, plasma concentrations of lipids, thyroxine and testosterone were assayed each month for 1 year beginning in September, while plasma lipoproteins from five of these animals were analyzed at the same dates using density gradient ultracentrifugation. All classes of plasma lipids (cholesterol, total glycerol and phospholipids) exhibited statistically significant seasonal variations in their respective concentrations, with simultaneous maxima (cholesterol: 207 +/- 39 mg/100 ml; total glycerol: 50 +/- 9 mg/100 ml; phospholipids: 266 +/- 25 mg/100 ml) during late fall-early winter, i.e., during the period of the year when plasma levels of both thyroxine and testosterone were minimal. Plasma lipids subsequently decreased to minimal levels either in early summer (cholesterol: 129 +/- 18 mg/100 ml; phospholipids: 178 +/- 20 mg/100 ml) or in late winter (total glycerol: 22 +/- 9 mg/100 ml). Very low density lipoproteins (d less than 1.015 g/ml) were found at low levels (less than 15 mg/100 ml) during the cold months, and then became detectable as trace components only. The total concentration of the mixed lipoprotein population (i.e., low density lipoproteins, Lp(a), and high density lipoprotein (HDL)-like particles) in the d 1.015-1.065 g/ml interval decreased by almost 50% from January to February (from 164.3 to 89.2 mg/100 ml), i.e., following a 10-fold increase in the level of plasma testosterone, and immediately before the rapid doubling in plasma thyroxine concentration. The staining intensity of the electrophoretic band with migration characteristics corresponding to those of Lp(a) decreased considerably during winter. At the same period of the year, lower density (1.032-1.055 g/ml) HDL-like particles disappeared. The concentration of lipoproteins with d 1.065-1.162 g/ml, which included Lp(a) particles in addition to typical HDL, equally underwent seasonal variations. These variations consisted of two successive maxima in late fall (426.4 mg/100 ml) and late winter (458.3 mg/100 ml) with two subsequent decreases leading to minima in February (327.8 mg/100 ml) and August (257.1 mg/100 ml). Finally, very high density lipoproteins (d 1.162-1.259 g/ml) were heterogeneous, containing both cholesterol-rich (d 1.162-1.227 g/ml) and phospholipid-rich (d 1.194-1.259 g/ml) subpopulations.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗