SEARCH · Search PubMed

Results for “patterning”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources

PubMed1984

Sleep and purposive behavior: inverse deviations from randomness of neuronal firing patterns in the feline thalamus. A new form of homeostasis?

In behaving cats trained to press a bar for small aliquots of milk reward, single neuronal firing patterns were monitored from the nucleus reticularis (NR) thalami during bar bressing (BP), subsequent quiet wakefulness with EEG spindles (S- QW ), grooming behavior (GR) and slow-wave sleep (SWS). The temporal patterns in the neuronal spike trains were analyzed using a non-parametric method based on relative relations between sequential spike intervals. The deviations of pattern occurrences from the random model were quantified. During BP, specific patterns occurred much more often while others occurred much less often than predicted by the random model. Patterns that were dominant during BP, were selectively suppressed or virtually eliminated during S- QW , GR and SWS, despite the increased firing rate; and, vice versa, patterns that were suppressed below chance level during BP, became dominant during S- QW , GR and SWS. The magnitudes of these inversions of the statistical distribution of patterns were not random but graded and positively correlated, thus indicating that they were homeostatically controlled. Since the inversions were already evident shortly after the satiated ceased bar pressing, they may be related to the 'need' for sleep. On the basis of the known mechanisms of pattern generation and changes in receptors for putative transmitters, it was postulated that the inversions of pattern distribution are related to the recuperative function of SWS, i.e. resensitization of receptors that had been desensitized during the animal's stereotypic BP performance. The NR and other neuronal ensembles seem to constitute an oscillatory system with two modes of reciprocal connectivities : one is supporting wakefulness and emission of specific firing patterns, and the other is incompatible with wakefulness and instead is associated with inversion of statistical distribution of firing patterns and recuperative function of SWS.

Animals↗

PubMed1992

Differential effects of peripheral damage on vibrissa-related patterns in trigeminal nucleus principalis, subnucleus interpolaris, and subnucleus caudalis.

Histochemistry for cytochrome oxidase reveals a vibrissa-related pattern in trigeminal nucleus principalis, subnucleus interpolaris, and the magnocellular portion of subnucleus caudalis. This pattern is apparent in late fetal animals and is disrupted by transection of the infraorbital nerve on the day of birth. We recently reported results suggesting that the cytochrome oxidase pattern reflects primary afferent-induced clustering of second order neurons in all of these nuclei. If this conclusion is correct, it should follow that primary afferent lesions made after the cytochrome oxidase pattern became established in the brainstem might have little effect upon it. Accordingly, we transected the infraorbital nerve (the trigeminal branch that supplies the vibrissae) on postnatal days 0-10 and evaluated the vibrissa-related pattern in the brainstem with cytochrome oxidase histochemistry at varying intervals after these lesions. If the infraorbital nerve was sectioned on postnatal days 0-2, the vibrissa-related pattern was absent in trigeminal nucleus principalis, and both subnucleus interpolaris and caudalis. If such lesions were made after postnatal day 9, there was no appreciable effect upon the cytochrome oxidase pattern in any portion of the trigeminal brainstem complex. However, if lesions were made between postnatal days 3 and 8, the density and clarity of the cytochrome oxidase staining pattern were reduced in interpolaris and caudalis, but not in principalis. This difference was not due to differential transganglionic degeneration in these nuclei. Tracing with horseradish peroxidase demonstrated qualitatively equivalent primary afferent losses in principalis, interpolaris, and caudalis. Immunocytochemistry with a monoclonal antibody directed against parvalbumin also demonstrated a vibrissa-related pattern of cell bodies in principalis and interpolaris in rats killed on postnatal day 9 or later ages. The combination of retrograde tracing and immunocytochemistry revealed that the parvalbumin-immunoreactive neurons in principalis projected to thalamus while those in interpolaris were not labelled by tracer injections into the thalamus, midbrain, cerebellum or spinal cord. Infraorbital nerve transections made as late as postnatal day 8 resulted in a sharp decrease in the staining of parvalbumin-positive neurons in interpolaris, but not in principalis. Lesions made on postnatal day 10 had no qualitative effect upon parvalbumin-positive neurons in any portion of the trigeminal brainstem complex. The results of this study support the conclusion that the vibrissa-related cytochrome oxidase pattern in principalis becomes independent of primary afferent input at a very short interval after its initial appearance. In contrast, the patterns in more caudal portions of the trigeminal brainstem complex require maintenance of primary afferent input for a much longer postnatal period.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1996

Mechanisms of pattern generation in co-cultures of embryonic spinal cord and skeletal muscle.

Spontaneous output patterns of embryonic spinal cord slices in vitro were investigated in order to study the formation of pattern-generating networks. Patterns of spontaneous contractions of skeletal muscle fibers were recorded in co-cultures of embryonic rat spinal cord, dorsal root ganglia and skeletal muscle. A part of these contractions was shown to be driven by spinal circuits. These neuron-driven activity patterns changed from random to rhythmic when the inhibitory synapses in the spinal cord were blocked by strychnine, bicuculline or both. Rhythmic patterns consisted of bursts of activity (tetanic contractions) followed by periods of relaxation. The transition from random to rhythmic patterns occurred during a period of heavily increased rate of activity. Presynaptic inhibition was not involved critically in the generation of rhythmic patterns. Such patterns were, however, modulated through muscarinic and alpha-adrenergic receptors. Neither NMDA nor glutamate nor its uptake blocker dihydrokainate induced rhythmic patterns of contraction, although NMDA in the presence of low magnesium increased moderately the rate of random activity. In order to study the size of pattern-generating networks, parts of the spinal cord slices were sectioned during rhythmic activity. Tangential cuts at the lateral or dorsal side of the slices reduced either the rate or the duration of the bursts or both. Sagittal cuts suppressed the activity almost totally. These findings suggest that the pattern generators in the slices consist of excitatory networks covering the entire slice, and that these networks reverberate following spontaneous activity of some distributed elements.

Animals↗

PubMed2005

Unique dietary patterns and chronic disease risk profiles of adult men: the Framingham nutrition studies.

OBJECTIVE: To identify the dietary patterns of adult men and examine their relationships with nutrient intake and chronic disease risk over long-term follow-up. DESIGN/SUBJECTS: Baseline 145-item food frequency questionnaires from 1,666 Framingham Offspring-Spouse cohort men were used to identify comprehensive dietary patterns. Independent 3-day dietary records at baseline and 8 years later provided estimates of subjects' nutrient intake by dietary pattern. Chronic disease risk factor status was compared at baseline and 16-year follow-up across all male dietary patterns. STATISTICAL ANALYSES: Cluster analysis was applied to food frequency data to identify non-overlapping male dietary patterns. Analysis of covariance and logistic regression were used to compare nutrient intake, summary nutritional risk scores, and chronic disease risk status at baseline and follow-up by male dietary pattern. RESULTS: Five distinct and comprehensive dietary patterns of Framingham Offspring-Spouse men were identified and ordered according to overall nutritional risk: Transition to Heart Healthy, Higher Starch, Average Male, Lower Variety, and Empty Calories. Nutritional risk was high and varied by dietary pattern; key nutrient contrasts were stable over 8-year follow-up. Chronic disease risk also varied by dietary pattern and specific subgroup differences persisted over 16 years, notably rates of overweight/obesity and smoking. CONCLUSIONS: Quantitative cluster analysis applied to food frequency questionnaire data identified five distinct, comprehensive, and stable dietary patterns of adult Framingham Offspring-Spouse cohort men. The close associations between the dietary patterns, nutritional risk, and chronic disease profiles of men emphasize the importance of targeted preventive nutrition interventions to promote health in the male population.

Adolescent↗

PubMed1988

A pattern formation mechanism to control spatial organization in the embryo of Drosophila melanogaster.

It is known that cells are already committed to a particular segment at the cellular blastoderm stage during embryogenesis of Drosophila melanogaster. Recently, several segmentation genes have been observed to be expressed in a sequence of banded spatial patterns in the syncytial blastoderm, prior to the formation of the cellular blastoderm. It is demonstrated in this paper that a two component reaction-diffusion (RD) system with net production functions which are antisymmetric with respect to the uniform steady-state values, is capable of producing a sequence of seven spatial patterns in the syncytial blastoderm. The sequence of patterns obtained exhibit a strong preference for banded or striped patterns. The first pattern is a simple anteroposterior gradient while the second is a gradient in the dorsoventral direction. The next five patterns are a sequence of banded patterns which exhibit frequency doubling, i.e. the number of bands in each pattern tend to be double the number in the previous pattern. The predicted pattern sequence is comparable to that observed in the expression of some segmentation genes. It is suggested that a pattern formation mechanism based on such an RD system may exist in the embryo where it produces a sequence of prepatterns to regulate the expression of various segmentation genes leading ultimately to a segmented embryo. There is sufficient spatial information in the sequence of banded prepatterns for the segments to be unique.

Animals↗

PubMed2000

Slow discrimination of contrast-defined expansion patterns.

We compared observers' performance in the same complex motion discrimination task using stimuli defined by luminance or by contrast. They were asked to discriminate between a centred expansion pattern, constructed from four patches of outwards motion, and a distorted expansion pattern, constructed with one patch containing inwards motion and three patches containing outwards motion. We measured performance versus duration and found that for luminance-defined patterns, observers were able to discriminate correctly between these patterns in 75% of trials when the stimulus duration was 200 ms. For contrast-defined patterns, observers required over 2 s to reach this level of performance. Observers did not require such long durations to discriminate correctly between the contrast-defined expansion patterns when the patterns contained fewer patches or when the distorted patterns contained more patches of inwards motion. This suggests that observers performed the task by searching for a patch that contained a pattern moving inwards. There was no such effect on performance with the luminance-defined patterns. These results also suggest that contrast-defined patterns are processed too slowly to provide an input to specialised optic flow detectors that guide navigation in real time. Further, the differences in performance may be due to processing delays from sequential processing of the contrast-defined local motion signals.

Contrast Sensitivity↗

PubMed2000

Correlates of the "western" and "prudent" diet patterns in the us.

PURPOSE: Underlying the diversity and changeability of US eating habits are fundamental dietary patterns shaped by common sociohistorical experiences. Currently, little is known of what patterns exist or their associations with sociodemographic/lifestyle factors. We examined these issues in third National Health and Nutrition Examination Survey data.METHODS: Analyses were based on 5,794 US-born, white participants. Interviews included a 60-item food frequency questionnaire (FFQ) and questions on sociodemographics and health behaviors. Dietary patterns were identified by principal components analysis on FFQ responses. Component scores representing intake level of each pattern were dichotomized at the median. Logistic regression analysis was used to estimate odds ratios (OR) and 95% confidence intervals (CI).RESULTS: We identified two primary dietary patterns-a "western" pattern characterized by processed and red meats, eggs, potatoes, and refined grains, and a "prudent" pattern characterized by cruciferous vegetables, greens, carrots, salads, and fresh fruits. The two patterns occurred across geographic regions and in both women and men. After age- and sex-adjustment, the "western" diet was associated with rural residence (OR = 1.9, 95% CI 1.7-2.2), working class status (OR = 1.4, 95% CI 1.2-1.6), and lack of high school completion (OR = 1.6, 95% CI 1.4-1.8). The "prudent" diet was associated with high school completion (OR = 2.8, 95% CI 2.5-3.3) and behaviors reflecting greater health awareness, such as daily physical activity (OR = 2.0, 95% CI 1.8-2.2), non-smoking (OR = 2.1, 95% CI 1.8-2.4), and supplement use (OR = 1.8, 95% CI 1.6-2.0).CONCLUSIONS: The two dietary patterns resemble those found in previous US studies. Findings regarding correlates agree with social histories describing the emergence of those patterns. Principal components analysis is potentially useful for identifying fundamental dietary patterns for future investigations of diet-disease associations.

Journal Article↗

PubMed1998

Three squares or mostly snacks--what do teens really eat? A sociodemographic study of meal patterns.

PURPOSE: To categorize U.S. adolescents' meal patterns and related differences in dietary quality. METHODS: Using data from the Continuing Survey of Food Intake by Individuals, 1989-1991, meal patterns from 3 days of adolescents' (ages 11-18 years) intake (n = 1310) were examined. Consistency of meal pattern intake and associated nutrient quality was determined. Logistic regression was used to examine the effects of several sociodemographic characteristics on meal pattern consistency. RESULTS: A higher percentage of adolescents consumed a meal pattern that included 3 meals/day than any other meal pattern: 57.4-58.7% on any given day. Forty-one percent of adolescents fell into the consistent (at least two meals on all 3 days), and only 3.5% fell into the inconsistent meal (one meal, with or without snacks, or snacks only, on all 3 days) pattern category. Logistic regression results indicated that being black [adjusted odds ratio (AOR) = 4.19, 95% confidence interval (CI) (1.90, 9.27)], older (15-18) [AOR = 1.41, 95% CI (1.19, 1.67)], and from a single-parent household [AOR = 2.60, 95% CI (1.23, 5.52)] were predictive of an inconsistent meal pattern. School lunch has a positive impact on intake, increasing a consistent meal pattern from 36.0% to 44.9%. CONCLUSIONS: Adolescents who consume at least two meals (with or without snacks) on a consistent basis have an adequate intake of calories and a more nutrient-dense diet with respect to calcium, iron, vitamin E, and fiber than those with other meal patterns. From the perspective of following a diet to prevent chronic diseases in adulthood, adolescents regardless of meal pattern, consume a diet that is too high in fat, sodium, and protein, and too low in fiber.

Adolescent↗

PubMed2006

Association between dietary patterns and anaemia in adults from Jiangsu Province in Eastern China.

The objective of the present study was to investigate the association between food patterns and anaemia among Chinese adults. It was a cross-sectional household survey undertaken in 2002. The sample contained 2849 men and women aged 20 years and above, and had a response rate of 89.0 %. Factor analysis was used to identify food patterns based on a food-frequency questionnaire. Logistic regression was used to relate food patterns to anaemia. A four-factor solution explained 30.5 % of the total variance. After adjusting for socio-demographic factors and four distinct food patterns, the 'traditional' (rice, vegetable, wheat flour), 'sweet tooth' (drinks, cake) and 'healthy' (whole grains, fruits, vegetables) patterns were independently associated with anaemia. 'Traditional' and 'sweet tooth' patterns were positively associated with anaemia, whereas the association with 'healthy' food pattern was negative. No association was observed between the 'macho' pattern (meat and alcohol) and anaemia. Compared with the lowest quartile (Q1) of the 'traditional' pattern, the highest quartile (Q4) had a higher risk of anaemia (men: odds ratio (OR) 2.60, 95 % CI 1.38, 4.88; women: OR 3.40, 95 % CI 2.14, 5.39). For the 'sweet tooth' pattern, compared with the lowest quartile (Q1), the OR of the highest quartile was 2.34 (95 % CI 1.47, 3.73) for men and 2.02 (95 %CI 1.31, 3.13) for women. The fourth quartile of healthy food was associated with a lower risk of anaemia (men: OR 0.50, 95 % CI 0.31, 0.79; women: OR 0.51, 95 % CI 0.34, 0.75). Women in the north had a higher risk of anaemia (OR 2.49, 95 %CI 1.80, 3.43). Food patterns were associated with anaemia in this area with a high prevalence of anaemia.

Adult↗

PubMed2004

Interaction of dense breast patterns with other breast cancer risk factors in a case-control study.

The question of interactions between breast density and other breast cancer risk factors is of interest, since it bears upon the use of density as a marker for changes in breast cancer risk. We studied breast parenchymal patterns and 13 other potential risk factors for breast cancer in 172 breast cancer cases and 338 age-matched controls in Singapore. Dense breast patterns were defined as having Tabar parenchymal pattern IV or V. We found significant interactions between dense patterns and ethnic group (P=0.046), and between dense patterns and number of deliveries (P=0.04). Among women with nondense breast patterns, the non-Chinese had lower risk than the Chinese with an odds ratio (OR) of 0.47 (95% CI 0.24, 0.88), whereas in those with dense patterns, the non-Chinese had considerably higher risks (OR=5.34, 95% CI 0.54, 52.51). Alternatively expressed, the increased risk with dense patterns was only observed in the non-Chinese (OR=13.99, 95% CI 1.33, 146.99). Among parous women, the protective effect of three or more deliveries was only observed in those with dense breast patterns (OR=0.21, 95% CI 0.06, 0.70). Suggestive but nonsignificant interactions with dense patterns were observed for ever having delivered, age at first delivery, breast feeding and body mass index. The results are consistent with dense breast patterns as a marker for hormonal modification of breast cancer risk.

Adolescent↗

PubMed2006

Dietary patterns and associated lifestyles in preconception, pregnancy and postpartum.

OBJECTIVE: To identify dietary patterns in women who are planning immediate pregnancy in preconception, weeks 6, 10, 26 and 38 of pregnancy, and 6 months postpartum, and to describe how particular lifestyles, the body mass index (BMI) and sociodemographic factors are associated to these patterns. DESIGN: Longitudinal study throughout the reproductive cycle of food consumption carried out in a Spanish Mediterranean city. SETTING: Faculty of Medicine and Health Sciences, Rovira i Virgili University. SUBJECTS: In total, 80 healthy female volunteers who were planning immediate pregnancy. INTERVENTIONS: A seven-consecutive-day dietary record was used to evaluate the dietary intake. Exploratory factor analysis was used to identify the main dietary patterns in each of the periods. Fitted multiple linear regression models were used to study the associations between the lifestyle and sociodemographic variables, and each dietary pattern. RESULTS: The 'sweetened beverages and sugars' pattern was identified from preconception to 6 months postpartum and the 'vegetables and meat' pattern to the end of pregnancy. The 'sweetened beverages and sugars' pattern is positively associated with smoking and negatively associated with physical activity before conception and in the first trimester of pregnancy. The 'vegetables and meat' pattern is negatively associated with the BMI during the preconception period and positively associated with age in weeks 10 and 38 of pregnancy. It is shown that the patterns do not change significantly throughout the period studied. CONCLUSIONS: We have identified two stable dietary patterns from preconception to postpartum. The 'sweetened beverages and sugars' pattern is associated with habits of risk for the health of the pregnant woman and her offspring. SPONSORSHIP: 'Comisión Interministerial de Ciencia y Tecnología' (CICYT: ALI89-0388) and 'Instituto de Salud Carlos III', RCMN (C03/08), Madrid, Spain'.

Adolescent↗

PubMed2000

Correlation of polyelectromyographic patterns and clinical upper motor neuron syndrome in hemiplegic stroke patients.

OBJECTIVE: To investigate the correlation between movement patterns, measured by polyelectromyography (PEMG), and clinical upper motor neuron (UMN) syndrome in stroke patients. DESIGN: PEMG patterns, recorded from pairs of flexor-extensor muscles during voluntary maneuvers, and motor outcomes were assessed approximately 1 month after stroke (early stage). Motor outcomes were reassessed 6 months later (late stage). PARTICIPANTS: Thirty-nine hemiplegic stroke patients and 18 healthy control subjects. MAIN OUTCOME MEASURES: Passive stretch reflexes (PSRs), Brunnstrom's stages, and walking ability. RESULTS: Six PEMG patterns, varying from complete reciprocal to complete synchrony, were identified. Higher PEMG pattern scores were associated with better Brunnstrom's stages (r > .80), walking ability (r > .39), and some PSRs (r < -.37). PEMG patterns could separate patterns 1 and 2 from patterns 3 and 4 for patients with early Brunnstrom's stages 1 and 2. Patterns 1 and 2 (reduced agonist electromyographic activities) indicated weakness and resulted in the worst motor outcomes. Patterns 3 and 4 (cocontraction and coactivation) indicated spasticity and associated synergistic movements. Patients with patterns of 5 and 6 (reciprocal electromyographic activities) had more selective motor control. CONCLUSIONS: PEMG patterns correlate with clinical UMN syndromes and may allow treatment strategy planning on the basis of underlying motor control, as well as the prediction of final motor outcomes soon after stroke, even in patients who cannot move their legs initially.

Aged↗

PubMed2000

Ground reaction force pattern in limbs with intermittent claudication.

OBJECTIVES: to investigate the presence of a ground reaction force pattern specific to the patient with unilateral intermittent claudication (IC), and the relationship of this pattern with onset of claudication. DESIGN: identification of impulse pattern during gait of lower limbs with and without ischaemia, in patients with unilateral IC and controls. METHODS: thirty patients with unilateral IC and six peripheral arterial disease non-claudicant patients had their gait recorded using the F-Scan system during a treadmill test. Their plantar impulse pattern was calcuated. Examined lower limbs were subdivided into groups: ischaemic limbs (30), contralateral limbs (30) and lower limbs of patients without IC (12). Two impulse patterns were found: the descending one, where impulse values decrease during gait, and the non-descending one, where these values do not decrease during gait. The numerical distribution of patterns among limb groups was determined and their ratios compared. Correlation between claudication onset and impulse pattern was also investigated. RESULTS: most ischaemic limbs exhibited a descending pattern, in contrast with control and contralateral non-ischaemic limbs (p<0.02). There was no relationship between impulse pattern and claudication onset. CONCLUSIONS: ischaemic lower limbs present the descending pattern of plantar impulse. No relationship exists between this pattern and claudication pain.

Adult↗

PubMed1989

[Motor seizure patterns: a comparative analysis of tonic, psychomotor and psychogenic seizures].

The motor patterns are self-regulating standardized movement models under normal and pathological conditions. Once learned and then automatized, they form the elements of the voluntary motor activity. Accordingly even the motor phenomena of epileptic seizures are defined as models or patterns. This paper is concerned with the question whether the epileptic patterns are to be associated to the neurophysiological regulatory processes of voluntary motoricity or whether these are pathological processes without relation to the physiological movement patterns. At the outset a short introduction to the neurophysiological basis of the voluntary motoricity is presented, which is built up according to the medullary organization of the cortex and taking into consideration the movement control through "feed forward" and "feed back". To the motor patterns of generalized tonic seizures connections to ontogenetic and phylogenetic old movement patterns and their activation through the epileptic excitation are denied. The tonic seizures are considered as pathological epileptic patterns, which are caused as a result of epileptic excitation, following their own dynamics. They represent a clear marking of maximum discharges of the cerebral structures, which control all other neuronal processes as well. The motor phenomena concerning the psychomotor seizures are described as specific patterns in respect of patients and types of seizures. To be differentiated are the elementary patterns of the first stage of seizures and the patterns of psychomotor twilight states. They represent denatured fragments of physiological motoricity and biological behavioural patterns. They would be brought in motion by the epileptic excitation, which in turn could lead to extensive motor phenomena.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

The evolution of chemical patterns in reactive liquids, driven by hydrodynamic instabilities.

We summarize our activity in unveiling a very wide phenomenon: When a chemical reaction takes place at a liquid interface, spectacular patterns of product form (see Plate 1). The pattern formation phenomenon is general, and is observed in reactions between liquids separated by a membrane, in liquids subjected to gaseous reactants, and in photoreactive liquids. We have demonstrated the phenomenon on over 100 different reactions of all types, thus discovering what we believe to be one of the widest macroscopic pattern formation processes known to chemistry. As can be seen in the accompanying pictures, the richness, beauty, and variations in types of patterns can be breathtaking. Two important aspects of these patterns are noted: First, the patterns are true far-from-equilibrium structures, which are maintained only as long as reactants are available, or only as long as light energy is supplied to the system; and second, the chemical products that form the patterns are not precipitates, but are entirely soluble in the liquid in which they form. Thus, if the containers in which the patterns form are shaken or stirred, a homogeneous solution results. Our research of this phenomenon concentrated on three main aspects. The first one was phenomenological. Here we explored the scope and generality of the phenomenon, motivated both by the aesthetic appeal of the phenomenon, and by the puzzle of how is it that such a wide-scope, experimentally simple phenomenon, has by and large, escaped the attention of the scientific community.The second aspect was devoted to the understanding of the underlying general mechanism. Of the many mechanisms we analyzed and tested, some very complex, others quite trivial, the one that fits the majority of the physical and chemical observations is the following: By performing a reaction through a liquid interface, a concentration gradient of the product forms near the interface. We have shown that in many cases, these gradients lead to hydrodynamic instabilities, which then break nonlinearly into a pattern which onsets slow convections. In other words, we found that these patterns mark the route along which a chemical instability relaxes. The third aspect of our research was theoretical. Here we concentrated in depth on one of the reactions (the Fe(+2)/Fe(+3) photoredox reaction), determined all its important physical parameters, and modeled its behavior theoretically. Our model, which was based on the instability buildup described above, was solved numerically, and its results compared with computerized image analysis of the evolving patterns; very good agreement between theory and experiment, was obtained. (c) 1995 American Institute of Physics.

Journal Article↗

PubMed2000

Assessment of occupational exposure patterns by frequency-domain analysis of time series data.

Laboratory evidence increasingly points to exposure pattern characteristics, including the duration, frequency, and timing of the exposure during the day, as important factors influencing the biological response to extremely low-frequency magnetic fields. An exploratory analysis of exposure patterns was conducted in 113 electric utility workers employed as electricians, cable splicers, line workers, and power plant operators. The purpose of the study was to describe extremely low-frequency magnetic field exposure pattern characteristics of electric utility workers and evaluate grouping strategies for classifying occupational exposures based on their exposure pattern characteristics. Exposure patterns describe the cyclic fluctuation in exposures over time, and were evaluated by partitioning the variation of the time series into frequency components using frequency-domain analysis of the transformed and processed time series. The study samples were classified using traditional grouping strategies based on occupation and time-weighted average (TWA), and non-traditional grouping strategies based on cluster analysis of the standardized, low-frequency exposure pattern components. Rules for classifying samples into each group were developed using linear discriminant analysis, with the performance of each grouping strategy evaluated using a crossvalidation study design to estimate the rate of misclassification. Exposure patterns appeared unrelated to grouping strategies based on quartiles of the workday TWA, but were related to pattern clusters and occupation. The linear discriminant function produced very low misclassification error rates for the cluster grouping strategy (10%) compared to occupation (50%) and TWA quartile (69%) grouping strategies. Significant differences in the exposure patterns occurring between clusters and between occupational groups were observed, indicating that at least one of the spectral estimates in two of the groups were significantly different. However, patterns clusters produced the greatest contrast in exposure patterns of all grouping strategies, explaining 99 percent of the total variation compared to 58 percent of the total variation by occupation.

Electromagnetic Fields↗

PubMed2001

Association between dietary patterns and plasma biomarkers of obesity and cardiovascular disease risk.

BACKGROUND: Although the effects of individual foods or nutrients on the development of diseases and their risk factors have been investigated in many studies, little attention has been given to the effect of overall dietary patterns. OBJECTIVE: Our objective was to examine the associations of 2 major dietary patterns, Western and prudent, with biomarkers of obesity and cardiovascular disease (CVD) risk. DESIGN: We used factor analysis to define major dietary patterns for a subsample of men (n = 466) from the Health Professionals Follow-up Study by using dietary information collected from food-frequency questionnaires (FFQs) in 1994. We calculated partial correlation coefficients between pattern scores and biomarker values adjusted for age, smoking status, energy and alcohol intake, physical activity, hours of television watching, and body mass index. RESULTS: We derived 2 major dietary patterns that were generally reproducible over time. The first pattern (prudent) was characterized by higher intakes of fruit, vegetables, whole grains, and poultry. The second pattern (Western) was characterized by higher intakes of red meats, high-fat dairy products, and refined grains. Using pattern scores from 1994 and adjusting for potential confounders, we found significant positive correlations between the Western pattern and insulin, C-peptide, leptin, and homocysteine concentrations, and an inverse correlation with plasma folate concentrations. The prudent pattern was positively correlated with plasma folate and inversely correlated with insulin and homocysteine concentrations. CONCLUSION: Major dietary patterns are predictors of plasma biomarkers of CVD and obesity risk, suggesting that the effect of overall diet on CVD risk may be mediated through these biomarkers.

Adult↗

PubMed2003

Risk of hypertension among women in the EPIC-Potsdam Study: comparison of relative risk estimates for exploratory and hypothesis-oriented dietary patterns.

Analysis of dietary patterns is considered a useful approach to the examination of diet-disease associations. This study examined the risk of incident hypertension associated with dietary patterns in 8,552 women in the EPIC (European Prospective Investigation into Cancer and Nutrition)-Potsdam Study. The baseline examination was carried out between 1994 and 1998. During 2-4 years of follow-up (through May 15, 2002), 123 incident hypertension cases were verified by medical records. Two exploratory dietary patterns, a "traditional cooking" pattern (meat, cooked vegetables, sauce, potatoes, and poultry) and a "fruits and vegetables" pattern (fruits, raw vegetables, and vegetable oil), were identified by exploratory factor analysis and confirmed by confirmatory factor analysis. Additionally, a hypothesis-oriented pattern based on the Dietary Approaches to Stop Hypertension (DASH) Study was defined (fruits, vegetables, and milk products). Patterns' associations with disease risk were estimated by Cox regression. While no significant associations were observed for the traditional cooking pattern or the fruits and vegetables pattern after adjustment for potential confounders, women in the third quartile of the DASH pattern were at lower risk than women in the lowest quartile (hazard rate ratio = 0.51, 95% confidence interval: 0.29, 0.89). These results suggest that this hypothesis-oriented pattern might play an important role in the risk of hypertension.

Adult↗