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PubMed2001

The magnitude of variation in temperature within a year has an effect on the seasonal variations of chickenpox incidence in Japan.

We investigated the epidemic pattern of chickenpox incidence among 47 prefectures in Japan. There were two peaks in chickenpox incidence in all prefectures. The first peaks appear at almost the same time in a year, while the second peaks occur at different times with relatively different types of size and shape. The feature of the second peak might characterize the epidemic pattern of chickenpox. We first introduced the second peak index, that is, the ratio of the difference between the incidence at the point of the second peak and the minimum incidence between the first and second peaks to the difference between the incidence at the point of the second peak and the minimum incidence in the year. There was a close correlation between the second peak index and the magnitude of variation in temperature within a year corresponding to the difference between the maximum and the minimum of the monthly mean of the highest daily temperature. This is the first article focusing on the close relationship between the second peak of epidemic pattern of chickenpox incidence and the variation of temperature within a year.

Chickenpox↗

PubMedDate not supplied

Distribution analysis of the variation of B-factors of X-ray crystal structures; temperature and structural variations in lysozyme.

The B-factor (isotropic temperature factor) data for X-ray structures of hen egg-white lysozyme from the study of Young et al. (Young, Dewan, Nave, and Tilton J. Appl. Cryst. 1993, 26, 309-319) potentially contain information about the relative contributions of static and dynamic variation to these factors. The six structures of the protein were obtained at two widely different temperatures (100 and 298 K), with two crystal forms (monoclinic and tetragonal) and other experimental differences. In addition, the monoclinic lysozyme crystals with two molecules per asymmetric unit allow direct examination of variation between structures determined under identical conditions at both temperatures. The B-factors from these structures all have complex distribution functions as might be expected considering all of the influences that these values must reflect. The empirical cumulative distribution functions (eCDF's) of these data show that they are representative of complex, multicomponent distributions. Distribution analysis using the DANFIP procedure (Wampler, Anal. Biochemistry 1990, 186, 209-218) of the data sets reveals that they can be modeled as four to six Gaussian subpopulations, that these subpopulations do not correlate with specific atom types, specific amino acid residues or fixed locations in the structure. While they do seem to correlate with localized groupings of atoms, these grouping vary from structure to structure even within the same crystal under the same conditions. Temperature seems to have a global effect in this case, but it is clear that other factors including experimental error influence the distribution of B-factors within a given structure. This analysis also helps explain the oft observed lack of atomic level correlation between experimental B-factors and calculated mean square displacements from molecular dynamics simulations.

Algorithms↗

PubMed1999

Genetic variation of the riparian pioneer tree species populus nigra. II. Variation In susceptibility to the foliar rust melampsora larici-populina

Partial resistance of Populus nigra L. to three races of the foliar rust Melampsora larici-populina Kleb. was studied in a field trial and in laboratory tests, using a collection of P. nigra originating from different places throughout France. No total resistance was found. The partial resistance was split into epidemiological components, which proved to be under genetic control. Various patterns of association of epidemiological components values were found. Principal components analysis revealed their relationships. Only 24% of the variance of the field susceptibility could be explained by the variation of the epidemiological components of susceptibility. This variable was significantly correlated with susceptibility to the most ancient and widespread race of the pathogen, and with the variables related to the size of the lesions of the different races. Analysis of variance showed significant differences in susceptibility between regions and between stands within one region. Up to 20% of variation was between regions, and up to 22% between stands, so that these genetic factors appeared to be more differentiated than the neutral diversity (up to 3.5% Legionnet & Lefevre, 1996). However, no clear pattern of geographical distribution of diversity was detected.

Journal Article↗

PubMed2001

Unanticipated variations between expected and delivered pneumatic compression therapy after elective hip surgery: a possible source of variation in reported patient outcomes.

The differences between the pneumatic compression thromboprophylaxis delivered after elective total hip arthroplasties and that was expected were quantified before (49 patients) and after a concerted nursing education program (30 patients) that was designed to ensure maximum compliance and to verify the correct application of the devices. The expected therapy was not delivered to any of the patients monitored. Therapy was delivered only an average of 77.8% of the time during the expected treatment periods. During 99.9% of the expected therapy times, values of key outcomes-related parameters of the therapy delivered to the patients varied by >10% from expected values. These variations were not reduced significantly by medical and nursing education. This variation may be a significant confounding factor in comparatively evaluating thromboembolic disease outcome reports.

Adult↗

PubMed2001

Anatomical variations in the internal jugular veins of cancer patients affecting central venous access. Anatomical variation of the internal jugular vein.

PURPOSE: Establishing a reliable central venous access is an important procedure in clinical haematology and oncology. The purpose of this study was to determine how anatomical variations in the internal jugular vein (IJV) and its position in relation to the common carotid artery (CCA) in cancer patients affects external landmark puncture. PATIENTS AND METHODS: In 113 patients with haematological or oncological diseases we examined sonographically potential target regions for placement of a central catheter via the IJV. RESULTS: 36% of our patients showed anatomical variations in the IJV and surrounding tissue. CONCLUSIONS: External landmark puncture may be difficult in a considerable number of patients since the IJV might not be situated in the presumed location anteriorly or laterally to the CCA, or a normal lumen may not be present in approximately 1/3 of cancer patients. This study supports the use of ultrasound-guided techniques for central venous catheters particularly in haematological and oncological patients.

Adult↗

PubMed1953

Morphologic variation in pneumococcus. I. An analysis of the bases for morphologic variation in pneumococcus and description of a hitherto undefined morphologic variant.

The problem of morphologic variation in pneumococcus has been reviewed and the desirability of studying such variation through an examination of bacterial cells rather than of bacterial colonies has been pointed out. To further this objective, a new terminology to describe the morphologic variants of pneumococcus, potentially applicable to other bacterial species, has been proposed. A hitherto undefined morphologic variant of pneumococcus, the filamentous capsulated (fil+ S+) variant, has been defined and its relationship to the three previously recognized non-filamentous capsulated (fil- S+), nonfilamentous non-capsulated (fil- S-), and filamentous non-capsulated (fil+ S-) variants has been presented.

Streptococcus pneumoniae↗

PubMed2001

Seasonal variation in household, occupational, and leisure time physical activity: longitudinal analyses from the seasonal variation of blood cholesterol study.

The authors examined seasonal variation in physical activity in longitudinal analyses of 580 healthy adults from Worcester, Massachusetts (the Seasonal Variation of Blood Cholesterol Study, 1994-1998). Three 24-hour physical activity recalls administered five times during 12 months of follow-up were used to estimate household, occupational, leisure time, and total physical activity levels in metabolic equivalent (MET)-hours/day. Trigonometric models were used to estimate the peak-to-trough amplitude and phase of the peaks in activity during the year. Total activity increased by 1.4 MET-hours/day (121 kcal/day) in men and 1.0 MET-hours/day (70 kcal/day) in women during the summer in comparison with winter. Moderate intensity nonoccupational activity increased by 2.0-2.4 MET-hours/day in the summer. During the summer, objectively measured mean physical activity increased by 51 minutes/day (95% confidence interval: 20, 82) in men and by 16 minutes/day (95% confidence interval: -12, 45) in women. The authors observed complex patterns of seasonal change that varied in amplitude and phase by type and intensity of activity and by subject characteristics (i.e., age, obesity, and exercise). These findings have important implications for clinical research studies examining the health effects of physical activity and for health promotion efforts designed to increase population levels of physical activity.

Adult↗

PubMed1980

Concatenation of variations in plaque formation with variations in crevicular temperature.

The hypothesis was tested that variations in the temperature of gingival crevices are linked to variations in plaque formation. Fifty-nine abutment teeth to removable partial dentures were studied during four experiments, under various conditions of plaque formation, i.e. not brushing the teeth whilst wearing and not wearing dentures, and performing ordinary and then specialized tooth brushing whilst wearing dentures. The collation of temperature curves with plaque curves revealed a proportional relationship between the rate and magnitude of plaque formation and the rate and magnitude of the recorded temperature changes. Furthermore, the removal of plaque resulted in a reversal of induced temperature rises. The lowest crevicular temperatures were obtained with the practice of the specialized tooth brushing.

Adult↗

PubMed1979

Circulating levels of pregnancy specific beta 1 glycoprotein in late pregnancy: nyctohemeral and day-to-day variation, and variation during labour.

Circulating levels of pregnancy-specific beta 1 glycoprotein have been determined in a number of physiological situations in late pregnancy. The apparent variation in five subjects studied over a 24-hour period was not in excess of that due to the assay. Excess variation was apparent in 2 of 11 subjects studied daily for up to 8 days, and in 6 of 16 patients studied serially during labour.

Circadian Rhythm↗

PubMed1976

Is there a diurnal variation in the susceptibility of mouse skin to the tumorigenic action of methylcholanthrene? A study of tumour yield with special reference to the variation between cages.

Skin tumour development was studied in groups of mice painted once with 125 mug of 3-methylcholanthrene (MCA) either at 12:00 or at 24:00 MET. Eight animals were kept in each box. The animals were observed weekly for 20 months and all tumours were registered. There was no difference between the two groups of mice as regards tumour induction time or number of papilloma-bearing mice. In the groups of mice treated at 24:00 the number of skin tumours to develop was 9 per cent higher than in groups of mice treated at 12:00. This difference in papilloma yields is not statistically significant. Among female mice painted at 24:00 carcinoma-bearing animals were significantly more numerous (50 per cent) than among those painted at 12:00, whereas there was no difference between the groups of male mice. Considering the groups collectively (males + females), the intergroup difference (17 per cent) in advantage of painting at 24:00 was barely significant (0.5 less than p less than 0.10). There was no difference between the groups as regards the total number of carcinomas to occur. When the tumour yields in individual boxes were found to vary greatly. The slight increase in tumour yield after night painting correlates with the circadian variation in proliferative activity of the epidermidis. Previous reports in the literature have shown similar differences. Further investigations and better methods seem necessary before a definite conclusion can be drawn concerning a possible diurnal variation in the susceptibility of mouse skin to chemical carcinogenesis. It is also emphasized that it is necessary to exercise great caution when the results of classical epidermal chemical carcinogenesis experiments are to be interpreted. It seems necessary to observe animals for at least 15 months before any conclusion can be drawn.

Animals↗

PubMed1978

Seasonal variation in admissions of psychiatric patients and its relation to seasonal variation in their births.

Inpatient admissions to all psychiatric hospital beds in England and Wales in 1970-73 were studied by month of admission for eight diagnostic groups. The admission rates for schizophrenia showed a pronounced seasonal variation, with a maximum in summer. The seasonal pattern for schizophrenia was very similar to the one shown for mania, although somewhat less marked. The admission rates for neurosis and for the large group of 'all other non-psychotic mental illness' showed little evidence of seasonal variation as there was could largely be explained by social factors. In schizophrenic and manic patients, the pattern of seasonal admissions (peak months July and August) is similar to the pattern reported for their births (peak months February and March). This is consistent with the hypothesis of an abnormal seasonal pattern of parental conception as the cause of the abnormal birth pattern.

Bipolar Disorder↗

PubMed1990

Preparation of allergen extracts from the green alga Chlorella. Studies of growth variation, batch variation, and partial purification.

Allergen extracts were prepared from different raw materials of three strains of the unicellular green alga Chlorella (C. vulgaris, C. homosphaera and C. saccharophila). Growth variation, batch variation and composition of partially purified extracts were studied by analyzing total protein and carbohydrate content, protein and IgE-binding patterns and allergenic potency. Chlorella allergens were produced in the same proportions in early and late exponential growth phases but appeared partly degraded in the stationary phase. Uniform growth and extraction from Chlorella cells in the late exponential phase were demonstrated. Partially purified extracts from cells in late exponential phase contained 50% protein of the dry weight compared to 20% in crude extracts. The carbohydrate content was 20-30% of the dry weight of both crude and purified extracts. The allergenic potency of the purified extracts was 150-340% of the crude extracts, as assayed by RAST inhibition. The purified C. vulgaris extract showed a reduced IgE binding compared to crude extracts, while C. homosphaera and C. saccharophila extracts exhibited consistent IgE binding and are therefore suitable for in vivo and in vitro studies of allergenic properties of Chlorella.

Allergens↗

PubMed1988

Day-to-day variation of the frequency of ventricular premature contractions depends on variation of heart rates.

To examine the manner in which spontaneous variation in the frequency of ventricular premature contractions (VPCs) relates to the variation of heart rate (HR), 68 patients with frequent VPCs were studied, by using 24-hour ECG recordings. All patients had more than 40 VPCs/hour on an initial 24-hour ECG recording and a second recording was made within 2 months (mean: 15 days). For each patient, the HR-dependency of VPCs was evaluated. Plots of VPC frequency per minute (VPCs/min) vs. HR were made at 1-beat/min steps for all HRs recorded for at least 5 min during 24 hours. Based on the patterns of correlation between VPCs/min and HR observed at the first recording, patients were divided into 2 groups: 1) 26 with a positive correlation or the P group (a linear increase in VPCs/min with increasing HRs) and 2) 42 with a non-positive correlation or the NP group. The NP group included: 1) an increased VPCs/min at low HRs and a decrease at high HRs (38 patients), 2) a linear decrease in VPCs/min with increased HRs (2 patients) and 3) constant VPCs/min at all HRs (2 patients). The patterns of correlation were reproducible at the second recording period in 65 of 68 patients (96%). Variability in the VPC frequency per 24 hours between two 24-hour recording periods was significantly greater in the P than in the NP group, while the variability in the mean daily HR was similar between the 2 groups. Thus, the 95% confidence limit for spontaneous reduction in the VPC frequency was greater for the P (67%) than for the NP group (50%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1996

Domestic cats show episodic variation in plasma concentrations of adrenocorticotropin, alpha-melanocyte-stimulating hormone (alpha-MSH), cortisol and thyroxine with circadian variation in plasma alpha-MSH concentrations.

Blood samples were collected from 31 healthy domestic cats to characterize possible episodic and/or circadian variation in plasma concentrations of adrenocorticotropin (ACTH), cortisol, thyroxine and alpha-melanocyte-stimulating hormone (alpha-MSH). Samples were collected with minimal disturbance through indwelling jugular cannulae at two frequencies: at 20-min intervals for 3 h for evaluation of episodic variation, and at 2-h intervals for 48 or 72 h to identify possible circadian changes. Episodic peaks in profiles of all hormones were found in the majority of cats. When data were compared across four bleed periods (each of 3 h duration), no differences were detected in average hormone concentrations or characteristics of episodic pulses. Correlation analyses showed a significant (p < 0.001) relationship between concentrations of ACTH and cortisol (r = 0.44) when these hormones were measured in the same plasma sample. A weaker but significant correlation (r = 0.13, p < 0.05) was also detected between concentrations of ACTH and alpha-MSH, suggesting that proopiomelanocortin peptide secretion from the pars distalis and pars intermedia occurs at least on occasion in synchrony. No differences in hormonal profiles were noted when comparing data across sexes. Data from the studies designed to evaluate circadian change (48 and 72-h bleed periods) indicated that, of the four hormones, only concentrations of alpha-MSH changed with a significant circadian periodicity. A significant circadian component of period length 24-25 h was detected in 37% (seven of 19) of cats examined. Concentrations of alpha-MSH were greatest coincident with or shortly after the onset of darkness. These findings indicate that pituitary-adrenocortical hormones are secreted episodically in domestic cats and that, in contrast to the patterns shown by ACTH and cortisol, secretion of the pars intermedia product alpha-MSH occurs with a circadian rhythm in about one-third of cats.

Adrenocorticotropic Hormone↗

PubMed1991

Fermentation to short-chain fatty acids and lactate in human faecal batch cultures. Intra- and inter-individual variations versus variations caused by changes in fermented saccharides.

The fermentation to short-chain fatty acids, lactate, and ammonia from several non-starch polysaccharides, glucose, and albumin was investigated in 16.6% faecal homogenates. Increasing concentrations (0-30 mg/ml) of glucose, wheat bran, pectin, ispaghula, cellulose, or albumin incubated for 24 h in homogenates pooled from three individuals increased short-chain fatty acid production linearly. Amounts and ratios of short-chain fatty acids formed were highly dependent on the type of substrate fermented. Fermentable saccharides increased ammonia assimilation, in contrast to the metabolic inert cellulose. Nine faecal homogenates sampled from three individuals at three occasions were incubated for 6 and 24 h. The production of total short-chain fatty acids, acetate, propionate, and butyrate and the accumulation of D- and L-lactate changed considerably in relation to the type of substrate added (cellulose, ispaghula, wheat bran, pectin, gum arabic, and glucose; p less than 10(-4)-10(-7). In contrast, there were no significant (p greater than 0.05) differences in organic acid formation between the nine homogenates, and the intra- and inter-individual variations were of the same magnitude. Variations in fermentation, when measured as organic acid formation, were therefore related to the type of substrate fermented rather than the individual tested.

Adult↗

PubMed1990

Seasonal variations of pigmented naevi. Intercorrelations of clinical and histological variables with special reference to seasonal variation.

During 1984, junctional and compound naevi were registered significantly more often during the summer half-year (May-October) than the total number of naevi, which showed no seasonal variation. A series of 342 of these junctional and compound naevi have been the subject of a blind histological classification. Clinical information was obtained by a questionnaire mailed to the patients. The intercorrelations of 19 histological and 10 clinical variables were studied by chi 2-test. The seasonal variation of these variables was further studied by chi 2-test and by Hewitt's test. Patient's hair colour, eye colour and sex as well as mitoses and localization showed a significant correlation to season of the year. The trends of these findings, compared with the information about tumour duration, indicate a short-term latency effect of UV light on naevi which are excised during the summer half-year.

Adolescent↗

PubMed2004

Zonal and directional variations in tensile properties of bovine articular cartilage with special reference to strain rate variation.

UNLABELLED: THE AIMS of this study were: (i) to investigate the variation in the tensile properties of articular cartilage with depth through cartilage thickness and fibre orientation; (ii) to determine the effect of strain rate on tensile properties of articular cartilage. MATERIALS AND METHOD: All experimental work was performed on cartilage specimens taken from two bovine knee joints. Osteochondral plugs 12 mm in diameter were harvested with a special reamer from the femur and the tibial plateaux of each knee. Slices (0.2 mm thick), of articular cartilage were cut from the plug with a microtome. The predominant orientation of the collagen fibres on the cartilage surface was determined using the pinpricking technique. Each specimen used for the tensile test was cut, so as to produce a dumbbell shape, with a gauge length of 6 mm. Uniaxial tensile tests were performed on each specimen in order to determine the tensile Young's modulus, and ultimate tensile strength (UTS). In this investigation, these tensile tests were carried out at different strain rate: 1, 20, 50 and 70%/sec. RESULTS: As regards the zonal properties, it was found that tensile stiffness was greater in the superficial layer than in deep layer. However, a few specimens from the deep layer displayed similar or greater stiffness compared to the superficial layer. With respect to the directional properties, the specimens oriented parallel to the predominant alignment of collagen, were stiffer than those, which were perpendicular to it in each layer. However, only the results regarding the deep layer can be considered statistically significant. In regard to the variation of modulus with the strain-rate, the results showed that there is no significant increase of the modulus with increasing strain rate from 20 to 50% per second. However, at 70% per second, articular cartilage stiffness considerably increased by up to one order of magnitude greater than that determined at lower strain rates in both the superficial and deep layer. Moreover, the UTS of cartilage specimens tested at 70% per second showed a significant rise, reaching values of four to five times that of those measured at 1, 20 or 50% per second. CONCLUSION: The steep increases in both the stiffness and ultimate tensile strength of cartilage at high strain rates point to the existence in cartilage of a mechanism for its protection from damage by stresses arising in trauma, which are usually applied at high rates. This mechanism needs to be elucidated. The reduced anisotropy found in the present study pointed out that collagen is likely to be less organized in bovine cartilage than in the human and therefore, a study of its ultra-structure would be appropriate.

Adaptation, Physiological↗

PubMed2005

Do variations in disease prevalence limit the usefulness of population-based hospitalization rates for studying variations in hospital admissions?

BACKGROUND: Studies of geographic variation in hospitalizations commonly examine age- and gender-adjusted population-based hospitalization rates (ie, the numbers of persons hospitalized relative to what is expected given the age/gender distributions in the area population). OBJECTIVE: To determine whether areas identified as extreme using population-based hospitalization rates remain extreme when ranked by disease-based hospitalization rates (the numbers of persons hospitalized relative to what is expected given the amount of disease in the area). DESIGN: The authors examined 1997 Medicare data on both inpatient admissions and outpatient visits of patients 65 years and older in each of 71 small areas in Massachusetts for 15 medical conditions. For each area, the number of people having each condition was calculated as the sum of those hospitalized plus those treated as outpatients only. The authors used hierarchical Bayesian modeling to estimate area-specific population-based hospitalization rates, disease-based hospitalization rates (DHRs), and disease prevalence. MAIN OUTCOME MEASURE: The extent to which the same areas were identified as extreme based on population-based hospitalization rates versus DHRs. RESULTS: Area-specific population-based hospitalization rates, DHRs, and disease prevalence varied substantially. Areas identified as extreme using population-based hospitalization rates often were not extreme when ranked by DHRs. For 11 of the 15 conditions, 5 or more of the 14 areas ranked in top and bottom deciles by population-based hospitalization rates were more likely than not (ie, with probability > or = 0.50) to be at least 2 deciles less extreme when ranked by DHRs. CONCLUSION: Differences in disease prevalence can limit the usefulness of population-based hospitalization rates for studying variations in hospital admissions.

Aged↗