Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Individual variability”

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.

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

At least 541 records · Page 30Linked to original sources
PubMed2000

Individual differences in the subjective response to smoked cocaine in humans.

The individual variables that determine the effects of cocaine in humans are not well understood. In this study, we examined the relationship between the subjective response to cocaine and selected individual variables in cocaine-dependent participants. A single 0.4-mg/kg dose of smoked cocaine was received by 75 smoked cocaine users. The variables associated with increased subjective response to cocaine were male sex, presence of alcohol use, higher baseline Beck Depression Inventory (BDI) scores, and duration of cocaine use. The change in heart rate and diastolic blood pressure in response to cocaine delivery were also positively associated with the subjective response to cocaine. In contrast, body weight, years of schooling, and the change in the heart rate with the expectation of cocaine delivery were associated with a diminished subjective response to cocaine. The importance of these variables in maintaining the cocaine use behavior needs to be studied further.

Adult↗
PubMed1995

Service quality in hospital care: the development of an in-patient questionnaire.

Describes the development of a multi-item scale for assessing in-patient perceptions of service quality in an NHS or NHS Trust hospital. Presents evidence of the high reliability of the scale and its factor structure. Five intangible factors emerge: empathy, relationship of mutual respect, dignity, understanding of illness and religious needs, along with two tangible factors: food and physical environment. Results in a trial hospital indicate that patients' perceptions meet or exceed expectations in respect of four of the seven factors and 22 of the 49 individual variables. Of concern, however, while possibly not generalizable, must be the unfulfilled expectations in respect of the factors "relationship of mutual respect" and "understanding of illness" and the individual variables relating to the various communications between doctors and patients. Not unexpectedly, dissatisfaction is also expressed with the physical environment. Argues that the situation can only be remedied, usually, by a large injection of cash--an unlikely scenario.

Food Service, Hospital↗
PubMed1991

Age-related loss of auditory sensitivity in two mouse genotypes.

Frequency-specific auditory brainstem responses (ABR) (frequency range 2-31.5 kHz) were used to describe age-dependent alterations in frequency sensitivity in CBA/ca (to 30 months) and C57BL/6J (to 16 months) mouse genotypes. The two strains displayed an age-related loss similar to that of humans, with a primary decline in high-frequency sensitivity. CBA mice showed a slow, yet gradual decrease in sensitivity to high- followed by low-frequency until 18 months of age and a rapid deterioration at all frequencies thereafter. C57 mice demonstrated precocious aging in auditory sensitivity in an unsteady rather than gradual manner. By testing the same individuals on repeated occasions it was shown that, for C57 mice, the degenerative process was more precipitous with three phases, and that the individual variability was larger than that of CBA mice. It is suggested that the two mouse genotypes can be used to express the different aspects of human presbycusis in individual variability and modes of gradual or staggered progression.

Aging↗
PubMedDate not supplied

[The variability of the itch mite Sarcoptes scabiei de Geer (Acariformes, Sarcoptidae) in relation to scabies epidemiology. 3. The geographical and seasonal variability].

The statistical modes of individual variability of Sarcoptes scabiei females, developed and described by the authors in two previous papers, has been used to analyze the geographic, seasonal variability and to compare the mite populations with due consideration for the clinical features of the disease. Statistically significant differences in the size and proportion of the samples were found in Moscow, the Moscow region, and the town of Bishkek in spring and summer. A relationship was revealed between the degree of the female back chetoid cover joining and the disease duration, number of burrows in the skin integument and their sites.

Animals↗
PubMed2000

Determination of copper, selenium and zinc in human blood by inductively coupled mass spectrometry: the sources of uncertainty and variability of results.

The concentration of Cu, Se and Zn in whole human blood and plasma was analysed by inductively coupled plasma mass spectrometry. Method involved dilution of sample by diluted nitric acid and Triton X-100 and measurement of 65Cu, 77Se and 66Zn intensities. Calibration solutions were spiked by main interferents. In order to evaluate suitability of the method for recognition of alternation of trace elements concentration, the uncertainty of results was estimated. The major part of uncertainty was due to repeatability, the other source (calibration and interferences) were found to be of lesser importance. The resulting uncertainty of concentration of mentioned trace elements is low as compared to between individual variability. Short-term (within day) and long-term (between day) variability of trace elements concentration was investigated and compared with between individual variability too. The time variability was negligible except for Zn concentration. The alternations of trace elements concentration in patients with several renal diseases were investigated. Only in case of patients in end-stage renal disease: hemodialyzed patients and patient treated by continuous ambulatory peritoneal dialysis the significant alternations were proved.

Copper↗
PubMedDate not supplied

[Review of respiratory mechanics in animals. 3. Methodical and physiologic aspects of the use of the impulse oscilloresistometry system (OIS)].

The impulse oscillometry system (IOS) which was originally developed for human medicine was found to be suitable for analysing respiratory mechanics in spontaneously breathing animals. This technique is non-invasive. METHODOLOGICAL ASPECTS: In order to use the IOS-technique in animals, a tightly fitting face mask is necessary. Furthermore, a flexible tube needs to be inserted into the measuring system. While the tube does not influence the measured results significantly, the face mask may affect the measurements. Therefore, its influence on the measured respiratory impedance must be taken into account. To prevent methodological errors, the head and body position of the animal should be standardised during the IOS-measurement. Since the methodological variability of the system is very small, the measuring results are highly reproducible. PHYSIOLOGICAL ASPECTS: In growing subjects, all parameters of respiratory mechanics depend on body weight. Since respiratory physiology is influenced by circadian rhythms, measurements of different days are only comparable when they have been done each day at the same hour. Comparing the respiratory impedance of different animals of similar age and body weight, a considerable inter-individual variability was observed. Due to the low level of physiological intra-individual variability, the method seems to be especially useful for studying influences on the respiratory system (i.e. pharmaceutics, therapeutics) in long-term studies using the same group of subjects.

Animals↗
PubMed1989

[Individual schedule of administration of aminoglycosides with reference to anatomo-physiological and pathological factors].

Potentiality of designing individual dosage of sisomicin and gentamicin in regard to "patient factors" was estimated. 62 adult patients with various pulmonary diseases at the background of volemic disorders of diverse degrees were treated with the aminoglycosides under monitoring of their blood levels. Concentrations of sisomicin and gentamicin in serum 1, 3 and 6 hours after their single administration in a dose of 1 mg/kg were determined by HELC. The antibiotic pharmacokinetics was characterized by pronounced individual variability. The ratio of the difference between the upper and lower confidence limits to the average values of the steady-state volume of distribution, the total clearance and the mean residence time amounted to 70, 60 and 57 per cent respectively. To elucidate the cause of the variability multiple correlation analysis of the pharmacokinetic parameters by the "patient factors" was performed. The highest coefficient of the multiple correlation (r = 0.690) defined relation between the aminoglycoside concentration 1 hour after the injection and the hematocrit, globular volume and phase of the volemic disorders which was expressed in coded variables. The coefficient of the multiple correlation between the total clearance and the body surface area, concentrations of creatinine and urea in serum, hematocrit, circulating blood volume and the phase of the volemic disorders was equal to 0.439. Therefore, the consideration of the above factors allowed to explain only 20 per cent of the observed individual variability of the pharmacokinetic parameters. In this connection mediated prediction of total clearance and subsequently individual dosage of the aminoglycosides by the "patient factors" was expedient only until the primary data on the pharmacokinetic monitoring were obtained.

Adolescent↗
PubMed1988

Efficiency under record performance demands: exertion control--an individual difference variable?

Semiprofessional players ran basketball circuits under either normal or record performance demands. Lactate concentration and heart rate were measured as indexes of exertion. Number of dribbling errors, attempted shots, hits, and hit rate served as measures of performance and efficiency. Several individual difference measures were taken in order to identify those athletes who were capable of moderating the extent of exertion and of preserving their performance from impairment. The indexes of exertion rose sharply from normal to record trials. Correspondingly, the numbers of dribbling errors and of shots increased while the hit rate declined. However, there were considerable individual differences in restraining exertion and preserving efficiency--both indexes of exertion control. Neither achievement motive scores nor questionnaire items that ask for self-knowledge about exertion control could account for these differences. However, individuals capable of exertion control could be discriminated by an action-control scale that asks about postdecisional implementation of action steps (Kuhl, 1985).

Achievement↗
PubMed2000

Normal and abnormal day-to-day variability of urinary albumin excretion in control and diabetic subjects.

Urinary albumin excretion (UAE) is very variable from day to day. This variability, more or less potent, might by itself have a patho-physiological significance. We analyzed day-to-day UAE in 207 elderly (60-75 years) inpatients (134 with and 73 without diabetes mellitus) attending the department of internal medicine of the Angers University hospital. Twenty-four-hour urine was collected 3 times during a 5-10 day hospitalization period. One-hundred-fifty-one patients (73%) displayed normoalbuminuria (UAE<30 mg/24 h in 2 or 3 measures) while 56 patients (27%) had microalbuminuria (UAE within 30-300 mg/24 h in 2 or 3 measures). As the raw data of UAE was not normally distributed, we transformed UAE into the variable z=log (log (k + UAE)) where k is an integer and looked for a k value for which z might be normally distributed. We found that z was actually normally distributed for k=2. Mean value and coefficient of variation of z in the 3 measurements were used to define the level and the temporal intra-individual variability of UAE. Expressed in term of z, the day-to-day intra-individual variability of UAE showed a potent change (from large variability to small variability) at the particular level z=1.25, corresponding to UAE=30.8 mg/24 h. This value is precisely the level currently used to define microalbuminuria in diabetic subjects. It is remarkable that the day-to-day variability of UAE collapses when UAE crosses the level which has been used to define microalbuminuria.

Aged↗
PubMed2006

Biomechanical behaviour of the periodontal ligament of the beagle dog during the first 5 hours of orthodontic force application.

The aim of this study was to describe the mechanical behaviour of the periodontal ligament (PDL) in response to loading with different forces for a period of 5 hours. Seven young adult male beagle dogs (age 1.0-1.5 years) were used. After extractions and placement of implants, custom-made appliances on both sides of the mandible were used to measure the displacement of the second premolars. Tooth displacement was measured during 5 hours of force application. Each dog underwent two measurement sessions. One premolar was moved with a force of 100 cN in the first session and with 50 cN in the second. The contralateral premolar was moved with forces of 100 and 300 cN, respectively. Time-displacement curves showed a rapid instantaneous response lasting only a few seconds followed by a slowly decreasing creep displacement. The instantaneous response demonstrated a large individual variability, caused by both a dog and a force effect. Differences in tooth and PDL anatomy and in the orientation of the periodontal fibres are probably important in this respect. The individual variability faded after the first seconds of tooth displacement, when the viscoelastic properties of the periodontal fibres became more pronounced. The force effect was non-linear for the first minute. Higher forces did not lead to proportionally larger displacements. The non-linearity decreased in the second response. The PDL is a complex material that might be considered as a non-linear fibre-reinforced poroviscoelastic material.

Analysis of Variance↗
PubMed1998

Slower and more variable reaction times in schizophrenia: what do they signify?

Extensive research has demonstrated that schizophrenic subjects are slower than normal comparison subjects on a range of reaction-time tasks. Some investigators have also observed that schizophrenic patients exhibit larger intraindividual variability in reaction times when performing these tasks than do normal comparison subjects. This study, using a lexical decision choice reaction time (CRT) task, explored the relation of mean CRT and it intra-individual variability (CRT-SD) to psychiatric symptoms and to performance on executive-motor tasks in 26 medication-free schizophrenic out-patients and 17 normal comparison subjects. Schizophrenic subjects had both significantly slower and more variable CRTs which were unrelated to general intellectual abilities (IQ). Among schizophrenic subjects, both CRT and CRT-SD were significantly related to severity of psychotic symptoms, failure to maintain cognitive set, and poorer motor coordination and global functioning. After controlling for mean CRT, CRT-SD showed unique covariation with clinical symptoms (positive, disorganized and tension/hostility). Conversely, mean CRT showed unique covariation with the failure to maintain cognitive set and with stereotypic mannerisms, independent of CRT-SD. These results suggest that slower CRT and increased intra-individual variability in CRT, while not fully independent of one another, may reflect separate aspects of symptomatic and cognitive dysfunction in schizophrenia.

Adult↗
PubMed1995

A method evaluating population risks from chemical exposure: a case study concerning prohibition of chlordane use in Japan.

The proposed method evaluating population risks from chemical exposure is based on estimation of the individual variabilities in the internal concentration of the chemical of concern and estimation of the magnitude of toxic effect caused at a given internal concentration. We assume a log-normal distribution for individual variability and propose loss of life expectancy (LLE) as a measure of the magnitude of toxic effects. We applied it to the evaluation of the governmental action of prohibiting the use of chlordane as a termiticide in Japan. Because the method is applicable to both carcinogenic and noncarcinogenic chemicals, the cancer risk due to chlordane and the noncancer risk due to chlorpyrifos, a major substitute, were evaluated and compared. The estimated values of risk represented in terms of LLE are 0.10 days for residents of untreated houses, 1.9 days for residents of treated houses, and 4.4 days for termite control workers when chlordane is used, and 0, 2.8, and 31 days when chlorpyrifos is used, respectively. From the result of the case study, we can see that the prohibition of chlordane is not necessarily effective in reducing risk.

Adult↗
PubMed2003

Biological constraints simplify the recognition of hand shapes.

This study sought to identify constraints that might lead to a concise system of recognizing fingerspelling hand shapes. Previous studies of grasping suggested that hand shape is controlled using combinations of a small number of neuromuscular synergies, but fingerspelling shapes appear to be more highly individuated and, therefore, might require a larger number of degrees of freedom. Static hand postures of the American Sign Language manual alphabet were recorded by measuring 17 joint angles. Principal components (PCs) analysis was compared to the use of subsets of individual variables (i.e., joint angles) for reduction in degrees of freedom. The first four PCs were similar across subjects. Classification using weightings from these four components was 86.6% accurate, while classification using four individual variables was 88.5% accurate (thumb abduction, as well as flexion at the index and middle finger proximal interphalangeal joints and the ring finger metacarpalphalangeal joint). When chosen for each subject, particular four-variable subsets yielded correct rates above 95%. This superior performance of variable subsets over PC weighting vectors suggests that the reduction in degrees of freedom is due to biomechanical and neuromuscular constraints rather than synergistic control. Thus, in future application to dynamic fingerspelling, reasonable recognition accuracy might be achieved with a significant reduction in both computational and measured degrees of freedom.

Cluster Analysis↗
PubMed1997

Kinematic analysis of the locomotion symmetry of sound horses at a slow trot.

This study of the locomotion symmetry was undertaken to provide standard symmetry indices of a group of sound horses at the trot. Using a 3D data collection system, the kinematics of the limb joints of 13 clinically nonlame horses were recorded while trotting in the standard conditions of the clinical lameness examination. A kinematic symmetry indice based on an inter-correlation method was defined and applied to the vertical displacement-time and joint angle-time diagrams of the left and right joints of the horses. For each horse, the mean symmetry indice of each joint was calculated using values from 5 trials. For each joint, these means were then averaged. To evaluate the repeatability of the locomotion symmetry, the intra- and inter-individual variabilities of the symmetry indices were studied. The levels of symmetry of the markers of the trunk were generally lower than those of the limbs. Moreover, during the 5 trials these levels of symmetry were strongly variable but their mean values were very similar from one horse to another. In our experimental conditions the trunk presented a higher degree of freedom than the limbs. This high intra-individual variability indicated also that several trials are necessary to quantify the locomotion symmetry of a trotting horse. In the same way, a lower level of symmetry of the hindlimbs, compared to the forelimbs, was proved by their lower values of symmetry indices. As opposed to the supporting role of the forelimbs, the propulsive role of the hindlimbs may explain this feature.

Animals↗
PubMed2000

Training and overtraining markers in selected sport events.

PURPOSE: Varieties of symptoms are supposed to detect overtraining (OT). Besides the problems of diagnosis and analysis in elite athletes, a daily monitoring of training status takes place with measurement of the parameters serum urea (SU) and serum creatine kinase (CK); therefore, their meaningfulness will be examined, with special respect inter- and intra-individually. METHODS: Data were obtained from determinations during training from athletes in rowing and athletes of international level. RESULTS: For 6981 SU determinations (male, N = 717; female, N = 285), a slightly asymmetric normal distribution was found (male, 80%, 5-7 mmol x L(-1); female, 75%, 4-6 mmol x L(-1)). Values for women were approximately 1.5 mmol x L(-1) lower. Individual variability was enormous; there seems little point in setting fixed value as 8.3 mmol x L(-1) for men and 7.0 mmol x L(-1) for women as a critical limit for OT. CK has also been measured and evaluated in sports as an essential parameter for determination of muscular stress. Frequency distributions of CK in 2790 samples (male, N = 497; female, N = 350) presented an asymmetric normal distribution with distinct trend toward higher values being evident for the range between 100 and 250 U x L(-1). Conspicuously elevated values occurred in the ranges 250-350 U x L(-1) and 1000-2000 U x L(-1). Men's maximal values were 3000 U x L(-1) and 1150 U x L(-1) for women. Individual variability was enormous. Athletes with chronically low CK exhibited mainly low variability; those with chronically higher values exhibited considerable variability. CONCLUSIONS: Establishment of both parameters should be useful to determine individual baselines from a large number of samples. Determinations should be made at least every 3 d in standardized conditions. If a large increase is observed in combination with reduced exercise tolerance after a phase of exertion (2-4 d), then the possibility of a catabolic/metabolic activity or insufficient exercise tolerance becomes much more likely.

Biomarkers↗
PubMed1994

Effects of micronutrients and antioxidants on lipid peroxidation in human plasma and in cell culture.

Plasma levels of triglycerides, retinol, cholesterol, lipid-phase antioxidants (alpha-, gamma-tocopherols, beta-carotene, alpha-carotene, lycopene, beta-cryptoxanthin and lutein/zeaxanthin), and thiobarbituric acid-reactive substances (TBA-RS), as an indicator of lipid peroxidation, were repeatedly determined in nine individuals over a 3-month period. Levels of TBA-RS were positively correlated with plasma triglycerides and gamma-tocopherol, and negatively correlated with plasma carotenoids. These results were consistent with in vitro cell culture studies which showed increased TBA-RS for cells supplemented with linolenic acid and decreased levels when treated with beta-carotene. We conclude that TBA-RS measurements in plasma accurately reflect the level of peroxidizable substrate as modified by the presence of a variety of dietary antioxidants, particularly carotenoids. Although the inter- and intra-individual variabilities for TBA-RS are comparable with the micronutrients and antioxidants measured in this study, high interassay variability and the strong association with the more commonly measured plasma triglycerides suggest the TBA-RS assay to be of limited use in epidemiologic studies. However, this assay does appear to be useful in cell culture studies where experimental conditions can be better controlled. Low ratios of inter- to intra-individual variability in some of the plasma micronutrient and lipid-phase antioxidants measured suggest that multiple samples may be required to characterize individuals in studies evaluating the relation between these plasma constituents and disease incidence.

Animals↗
PubMed1987

Cross sectional echocardiographic assessment of great artery diameters in infants and children.

The pulmonary trunk and aortic root were measured on cross sectional echocardiograms in 173 normal subjects aged from one day to 15 years. Fifteen neonates were reexamined 3-6 days later. The great vessels were visualised in the parasternal long axis and short axis views. All measurements were made in end diastole and end systole by the leading edge method. The internal diameter (inner surface to inner surface) of the pulmonary trunk was also measured. The diameters of the great vessels correlated best with the square root of body surface area. Individual variability in cardiac growth gave a wide scatter of normal values. This was controlled for by calculating the ratio of the pulmonary trunk to aortic root for each subject. This ratio showed little individual variability and, except for the neonatal period, was remarkably constant throughout infancy and childhood (1.06 (0.06)). In the first 24 hours of life the ratio of the pulmonary trunk to the aortic root was significantly larger (1.29 (0.12)) but within one week it decreased to the "normal" ratio found in the older age groups. These normal data should be useful in assessing patients with congenital heart disease, particularly those in whom pulmonary blood flow is abnormal.

Adolescent↗
PubMed1998

Population pharmacokinetics of recombinant factor VIIa in volunteers anticoagulated with acenocoumarol.

This study establishes a population PK model for FVII clotting activity (FVII:C) after injection of recombinant activated factor VII (rFVIIa) to healthy volunteers. Twenty eight volunteers, anticoagulated with acenocoumarol, received one or two rFVIIa injections, with dose ranging from 5 to 320 microg/kg. The FVII:C kinetic was fitted to a 2 compartment model, with continuous "endogenous perfusion" mimicking endogenous activity. Estimated clearance was 2.4 1/h (20% inter-individual variability and 9% inter-period variability). The volume of distribution at steady-state appeared to be significantly dose dependent: 78 ml/kg for doses < or = 20 microg/kg and 88 ml/kg for doses > 20 microg/kg respectively, with 16% inter-individual variability. The dose producing 50% of the maximum drop of INR was estimated to be 2.2 microg/kg. The model will be used to better define the dosage regimen for future clinical developments.

Acenocoumarol↗