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At least 991 records · Page 55Linked to original sources
PubMed1994

Coordination of oral cavity and laryngeal movements during swallowing.

In this study, dynamic imaging was used to track the movements of oral cavity and laryngeal structures during swallowing in 10 normal adults subjects. The movements of tiny lead pellet markers attached to the lips, tongue, mandible, and soft palate, as well as anatomic landmarks on the hyoid bone, were measured in relation to a reference pellet affixed to the upper central incisors. Sagittal views of the oral cavity were obtained using standard videofluorography. Each subject produced 10 swallows of 12 ml of tap water followed by 5 swallows with a bite block placed between the molars. The recorded video images were input to a microcomputer where the x- and y-coordinates of the pellets were measured. Results of the analyses revealed considerable temporal overlap in the timing of oral cavity and laryngeal movements, widespread individual variability in coordination patterns and movement trajectories, and selective effects of the bite block. These data suggest the existence of individual adaptive strategies in the programming and control of swallowing movements.

Adult↗
PubMed1975

Biotelemetric investigation of the regulation of the cardiac frequency in animals with use of telestimulation. Model examinations in the neat.

A method for the assessment of behaviour of the cardiac frequency regulation in freely moving animals by means of telestimulation and biotelemetry is described. The results of the examinations allow, in spite of individual variability, a classification of the animals into different types of regulation by consideration of the biorhythm. The assessment of the individual type of regulation in correlation to the biorhythmic structure of the organism is of basic significance for the evaluation of its capacity of performance and adapation.

Adaptation, Physiological↗
PubMed1999

Genetics of asthma.

This report concentrates on pharmacogenomic and pharmacogenetic issues discussed at the National Asthma Campaign International Congress, including the current state of asthma genetics and the potential to identify novel targets using either array-based technology or by targeting kinase or other signal transduction pathways. In addition, the potential contribution of variability in the genes coding for primary drug targets is examined; it is likely that at least some inter-individual variability in treatment response can be explained by the variation in relevant genes. The use of anti-IgE and anti-cytokine approaches to the treatment of asthma is also reviewed.

Journal Article↗
PubMedDate not supplied

Effect of torso flexion on the lumbar torso extensor muscle sagittal plane moment arms.

BACKGROUND CONTEXT: Accurate anatomical inputs for biomechanical models are necessary for valid estimates of internal loading. The magnitude of the moment arm of the lumbar erector muscle group is known to vary as a function of such variables as gender. Anatomical evidence indicates that the moment arms decrease during torso flexion. However, moment arm estimates in biomechanical models that account for individual variability have been derived from imaging studies from supine postures. PURPOSE: Quantify the sagittal plane moment arms of the lumbar erector muscle group as a function of torso flexion, and identify individual characteristics that are associated with the magnitude of the moment arms as a function of torso flexion. STUDY DESIGN/SETTING: Utilization of a 0.3 Tesla Open magnetic resonance image (MRI) to image and quantify the moment arm of the right erector muscle group as a function of gender and torso flexion. METHODS: Axial MRI images through and parallel to each of the lumbar intervertebral discs at four torso flexion angles were obtained from 12 male and 12 female subjects in a lateral recumbent posture. Multivariate analysis of variance was used to investigate the differences in the moment arms at different torso flexion angles, whereas hierarchical linear regression was used to investigate associations with individual anthropometric characteristics and spinal posture. RESULTS: The largest decrease in the lumbar erector muscle group moment arm from neutral to 45-degree flexion occurred at the L5-S1 level (9.7% and 8.9% for men and women, respectively). Measures of spinal curvature (L1-S1 lordosis), body mass and trunk characteristics (depth or circumference) were associated with the varying moment arm at most lumbar levels. CONCLUSIONS: The sagittal plane moment arms of the lumbar erector muscle mass decrease as the torso flexes forward. The change in moment arms as a function of torso flexion may have an impact on prediction of spinal loading in biomechanical models.

Adult↗
PubMed2004

Inter- and intraindividual variability in ketamine dosage in repetitive invasive procedures in children with malignancies.

Midazolam/ketamine sedation has been used successfully in children undergoing painful invasive procedures. The authors prospectively assessed inter- and intra-individual variability in ketamine dosage for sedation in repetitive invasive procedures in children with malignancies. A total of 92 invasive procedures (58 lumbar punctures, 34 bone marrow biopsies; range: 2-9 procedures/patient) were performed on 25 children (median age: 12 years). Intravenous sedation consisted of 0.1 mg midazolam/kg and 0.5-1.0 mg ketamine/kg. Incremental dosages of ketamine (0.33 mg/kg) were given if necessary to achieve or maintain deep sedation. Primary outcome measure was the inter- and intraindividual ketamine dosage required to achieve adequate sedation; secondary outcome measures were the number of procedures with adequate sedation (Ramsay score of > 4), the number of adverse side effects, and the need for therapeutic interventions. All 92 invasive procedures were completed with satisfactory sedation levels in 88 procedures (95.7%). There was a great inter- and intraindividual variability in ketamine dosage required to achieve or maintain adequate sedation. In 12% of procedures side effects were seen, which required no or only minor interventions. Due to great inter- and intraindividual differences, ketamine dosage should be titrated toward the desired level of sedation. Thus, ketamine can be adjusted to the individual's need while achieving adequate sedation.

Adolescent↗
PubMed1997

Hominid thumb strength predicted by high resolution magnetic resonance imaging and force measurements in living subjects.

This study investigates whether in-vivo measurements of the morphology of the pollical distal phalanx (PDP) can be used to predict the maximum force that can be exerted by the thumb in flexion at the interphalangeal joint. A predictive equation was obtained via which measurements of fossil PDP's can be used to predict flexion force in hominids. A home-built insertable coil assembly, which increased the available magnetic field gradient strength from 10 to 40 (mT) m-1, was used to acquire high resolution T1-weighted 3D SPGR Magnetic Resonance (MR) images of the left and right thumbs of nine volunteers. The subjects' age, sex, weight, height and self-assessed hand-dominance were recorded. The MR images were transferred to a computer for reformatting of sections in the transverse and volar plane (VP). Measurements were made of the maximum length (ML), breadth (MB), tuft breadth (MT) and joint depth (JD) of the PDP. For each subject the maximum flexion force that could be exerted by each thumb was measured. The mean maximum flexion force generated was 8.21 kg (range 5.68-13.13 kg). Considerable inter-individual variability was observed in the magnitude of the force difference between the left and right thumbs and this is greatest in individuals with the strongest thumbs. The best model produced by multiple linear regression analysis of all the available data has a value of r = 0.77 and needs only the two covariates of sex and weight, i.e. FORCE = 2.217 + 0.6651 x WEIGHT + 2.488 x SEX. However, in order to be useful for predicting the maximum flexion force of the thumb in hominids the model should only contain those parameters which can be measured for fossil PDP's. Accordingly, the best predictive model has a value of r = 0.73 and needs only the two covariates of ML and JD, i.e. FORCE = -10.28 + 0.2053 x ML + 1.571 x JD. The maximum force predicted for any of the hominid fossil PDP's was not significantly different from those recorded for the volunteers in the present study, although they were on average somewhat lower than those obtained for modern humans. This may be a reflection of the hominid's overall smaller body weights.

Animals↗
PubMed2003

The neural basis of predicate-argument structure.

Neural correlates exist for a basic component of logical formulae, PREDICATE(x). Vision and audition research in primates and humans shows two independent neural pathways; one locates objects in body-centered space, the other attributes properties, such as colour, to objects. In vision these are the dorsal and ventral pathways. In audition, similarly separable "where" and "what" pathways exist. PREDICATE(x) is a schematic representation of the brain's integration of the two processes of delivery by the senses of the location of an arbitrary referent object, mapped in parietal cortex, and analysis of the properties of the referent by perceptual subsystems. The brain computes actions using a few "deictic" variables pointing to objects. Parallels exist between such nonlinguistic variables and linguistic deictic devices. Indexicality and reference have linguistic and nonlinguistic (e.g., visual) versions, sharing the concept of attention. The individual variables of logical formulae are interpreted as corresponding to these mental variables. In computing action, the deictic variables are linked with "semantic" information about the objects, corresponding to logical predicates. Mental scene descriptions are necessary for practical tasks of primates, and preexist language phylogenetically. The type of scene descriptions used by nonhuman primates would be reused for more complex cognitive, ultimately linguistic, purposes. The provision by the brain's sensory/perceptual systems of about four variables for temporary assignment to objects, and the separate processes of perceptual categorization of the objects so identified, constitute a pre-adaptive platform on which an early system for the linguistic description of scenes developed.

Afferent Pathways↗
PubMed2006

Measures of localized spinal muscle fatigue.

The objective of this study was to determine the best variable, if any, to indicate the level of localized muscle fatigue. Six male and six female subjects were studied while they exerted their maximal voluntary contraction and 40% of maximal voluntary contraction of spinal extensors in an isometric lifting activity. The electromyography (EMG) of erectores spinae at thoracic and lumbar levels was measured bilaterally. Also, the muscle bed blood volume, level of blood oxygenation to erector spinae at L3 level and heart rate were measured. The initial and final values of subjective feelings of fatigue through visual analogue score, rate of perceived exertions and body part discomfort rating were recorded. The mean maximal voluntary contraction forces for males and females were 899 (238) N and 431 (135) N respectively. The mean durations of hold in maximal voluntary fatiguing contraction were 68.1 (39.9) s and 72.3 (37.0) s for men and women respectively. By the end of the hold the force declined to 52% for males and 62% for females. The EMG amplitudes and median frequencies also progressively declined (p < 0.01). ANOVA revealed that the task percentile values of all variables were significantly different (p < 0.01). Gender had a significant main effect (p < 0.01). The correlation coefficients between force and other individual variables were weak to modest, but significant (p < 0.001). None of the single variables predicted fatigue reliably for either gender and levels of contraction. The regression equations developed were highly significant (p < 0.01) and they explained 96 to 98% of variance in both genders and contractions.

Adult↗
PubMed1997

[Fetal blood analysis--pro and contra].

OBJECTIVE: Fetal blood gas analysis (FBA) or micro blood gas analysis (MBU) is seen worldwide as an integral part of modern obstetrics. However, there are a number of obstetricians who practise obstetrics quite safely and competently without MBU. The aim of this study was to find out what effect MBU frequency (%) had on vital obstetric performance parameters. METHODS: This study was based on the obstetric parameters of 1,003 clinics in Ostwestfalen-Lippe in the years 1990-1996. The percentages of 10 principal variables (including cesarean section, forceps, acidosis rates, postpartal mortality) were calculated per clinic/year. Correlations (according to Kendall) were established between the individual variables to estimate the influence of MBU frequency (%) on the different variables. Data from the 1,003 clinics in the years 1990-1996 could be pooled. RESULTS: Approximately 91% of all clinics perform FBA. The mean MBU frequency is 6.1 +/- 10.1%, the median is 2.3%. Upward variance is large: the 90th percentile of MBU distribution amounts to 15.5, the 95th centile to 22.6%. There is no correlation between MBU frequency (%) and clinic size, measured by the number of children born per year. There is no statistically relevant connection between the acidosis rate (%) in umbilical artery (UA) blood and MBU frequency. The same holds true for mortality (%) of neonates in the first week. However, there is a highly significant positive correlation between MBU frequency on the one hand and cesarean and forceps rates (%) on the other. Clinics without FBA (n = 88, approximately 9%) have obstetric performance figures that are as good as those of the total amount of clinics examined. There is no correlation between the acidosis rate (pH < 7.100, UA (%)) and neonatal mortality in the first week. However, a significant correlation between pH values < 7.000 (UA) and an increased postnatal mortality (p < 0.001) has been observed. CONCLUSIONS: In analogy to cardiotocography, cesarean and forceps rates are increased in FBA, although there is no statistically significant decrease in acidosis morbidity and postpartal mortality. These figures support the observation that obstetrics without FBA is possible and legitimate. The significance of FBA for fetal diagnosis lies in the small number of cases where cardiotocograms are hard to interpret. Therefore, every obstetrician should be able to handle it. A new evaluation of pH values is discussed.

Asphyxia Neonatorum↗
PubMed1992

Interindividual variations in enzymes controlling organophosphate toxicity in man.

1 Interindividual variations in an unexposed population have been defined for five enzymes involved in organophosphate (OP) toxicity. The enzymes measured were: red blood cell acetylcholinesterase (AChE), lymphocyte neuropathy target esterase (NTE), serum cholinesterase (ChE), serum paraoxonase and serum arylesterase. 2 AChE and arylesterase were normally distributed in the population whilst the distribution of NTE, ChE and paraoxonase deviated significantly from normal. 3 Assay precision and intra-individual variability were measured for each of the enzymes; the effect on interindividual variation was assessed. 4 Variations in enzyme activities between individuals could have profound effects on susceptibility to OP toxicity. Prior determination of these enzymes may be predictive of susceptibility. 5 Lymphocyte NTE has some limitations as an indicator of exposure to neurotoxic OPs.

Acetylcholinesterase↗
PubMed2003

[An ischemic syndrome of the oculumotor nucleus: associated clinical and anatomical variations on a theme].

Nuclear syndrome of the oculomotor nerve was first described in 1981, it is characterized by the association of an ipsilateral third nerve palsy with a paresis of elevation in the contralateral eye. This syndrome can be caused by vascular or tumoral lesions in the upper midbrain. It is rarely due to ischemic unilateral mesencephalic lesions, because ischemic lesions of the midbrain are usually integrated in a diffuse involvement of the brainstem and the thalamo-sub-thalamic region. In case of nuclear syndrome of the third nerve due to isolated upper midbrain infarct in the paramedian territory, dependent on branches of the basilar artery, oculomotor symptoms are frequently isolated. On the contrary, in fascicular syndromes of the third nerve, resulting from stroke in more lateral territories upon branches of the posterior cerebral artery, many neurological symptoms are associated with the oculomotor signs. We describe 3 patients presenting with a characteristic nuclear syndrome of the third nerve, resulting from a unilateral paramedian ischemic stroke in the upper midbrain, confirmed by cerebral CT scan or MRI examination. Clinical presentation differed in each case, and marked contralateral hemiparesia, cerebellar syndrome and focal asterixis were associated in various ways with the stereotyped oculomotor disorders. In the 3 cases, the nuclear syndrome of the third nerve was associated with fascicular involvement of the nerve, in an unusual clinical picture. The theoretical distinction between nuclear and fascicular syndromes is supported by the anatomical description of the arterial segmentation in the upper midbrain, which remains debated since the first description. According to the variability of clinical presentations, it seems that the arterial territories may be more variable than initially described. Therefore, ischemic lesions of the upper midbrain may involve some vascular borderzones with a high inter-individual variability. Upper midbrain strokes may thus lead to variable clinical pictures.

Aged↗
PubMed1988

The aging lens: in vivo assessment of light absorption in 84 human eyes.

We have developed an apparatus and psychophysical paradigm for the reliable and practical measurement of light absorption by the human crystalline lens. Using this procedure we can partition a loss of sensitivity with aging into that attributable to changes in the lens and that due to other factors. The procedure eliminates effects of inaccurate refractive correction and misalignment, and reduces the effects of pupil size. Results on 84 eyes showed a gradual decrease in sensitivity with age, especially for short wavelengths. We noted considerable individual variability, which points up the value of using a procedure that assesses sensitivity loss due to lens absorption for each tested individual.

Absorption↗
PubMedDate not supplied

[The effect of degenerative cervical spine lesions and blood flow velocity in vertebrobasilar system in Doppler measurement].

The purpose of the study was to establish the effect of degenerative lesions of cervical vertebrae on blood flow velocity in the vertebrobasilar system measured by means of Doppler phenomenon using Transpect--TCD device according to generally accepted principles. The study was carried out in 20 healthy controls and 40 individuals with these lesions (aged 16-60 years). It was found that blood flow velocity in this arterial system is highly variable individually. In patients with degenerative changes pathological reduction of this velocity was found in this system which is an unquestionable evidence of the influence of these lesions on blood flow in vertebral arteries.

Adolescent↗
PubMed1994

[Leg volumetry: a precise method for quantification in phlebology].

UNLABELLED: Chronic venous insufficiency is usually quantified by venous pressure measurement, which is an invasive method. Air plethysmography has also been used, but it is expensive, time consuming and only suitable for sophisticated research laboratories. Leg volumetry might be suitable for routine use, as it is simple, inexpensive, fast, non invasive and can be performed by non medical personnel. Here, we only evaluated its practicability, accuracy and reproducibility. PATIENTS: The study group included 28 legs of 14 healthy volunteers, and 22 legs of 11 patients suffering from varicose veins. METHOD: The device used was a plexiglass boot, 50 cm high, 20 cm wide. It was filled with water at 24 +/- 2 degrees C. The leg was immersed and the volume of water displaced recorded. RESULTS: Normal legs displaced a volume of 2,449 +/- 153 ml (mean +/- SD), range: 2,080-2,720, and variability 6.2%. Patients' legs displaced a volume of 2,576 +/- 290, range: 2,110-3,120, (p = 0.05 vs normals) and variability 11.2%. Accuracy was 0.7%, as from 2 consecutive measurements of the same patients' legs by 2 different observers. Intra-individual variability was 1.3%, as recorded in 12 repeated measurements of the same leg on different mornings. In normal legs, the difference between morning and evening volumes was statistically significant (18 +/- 15 ml, p = 0.0001), a finding consistent with the deterioration of the venous function in normal extremities during daily activities. CONCLUSION: This simple, cheap, objective, non-invasive reproducible and accurate method of leg volume measurement might be useful in routine practice for chronic venous insufficiency quantification.

Adult↗
PubMed2000

Eustachian tube function varies over time in children with secretory otitis media.

Impaired opening and closing functions of the Eustachian tube are considered to be pathogenic factors in secretory otitis media (SOM). As the clinical course of SOM is variable, the variability of tubal function is of interest. We aimed to explore the short- and long-term variability of tubal opening and closing functions in SOM. The study comprised 42 ears in 21 children (13 males and 8 females) with tympanostomy tubes due to SOM. The middle ear pressure was recorded during repeated passive forced openings, equalization of + 100 daPa and - 100 daPa by swallowing, Valsalva inflation and forceful sniffing. Test sessions were performed twice (separated by 30 min) on each of 2 days, with a mean interval of 3.7 months in between. In the forced opening test there was a considerable intra-individual variability over time. Expressed as SD of the mean, the variability of the forced opening and closing pressures in individual ears was on average 15% and 23%, respectively, between sessions and 20% and 30% respectively, between test days. In the equalization, Valsalva and sniff tests the rates of responses that changed from positive to negative between sessions and test days ranged from 12% to 33%. Female gender and retraction pockets were related to poorer opening function in the forced opening test. Ears with serous effusion (in contrast to mucoid) showed a similar trend and also a lower occurrence of positive equalization, Valsalva and sniff tests. It was concluded that Eustachian tube opening and closing functions are highly variable in ears with SOM. Consequently, single tubal function tests have low value when used as a prognostic tool in individual ears.

Analysis of Variance↗
PubMed2006

Common sequence variations in the P2Y12 and CYP3A5 genes do not explain the variability in the inhibitory effects of clopidogrel therapy.

The efficacy of the platelet P2Y12 receptor antagonist clopidogrel, which undergoes cytochrome-mediated metabolism to its active form, shows marked inter-individual variability. We investigated whether polymorphic variations in the P2Y12 gene, which have been linked to platelet aggregation phenotypes, or the cytochrome P450 3A5 gene 6986G > A polymorphism, which largely determines CYP3A5 expression, influence the response to clopidogrel therapy. Fifty-four patients listed for elective percutaneous coronary intervention were studied using ADP-induced optical aggregometry, whole-blood single platelet counting (WBSPC) aggregometry, and flow-cytometric analysis of platelet P-selectin expression and platelet-monocyte conjugate formation. Platelet reactivity was measured at baseline, 4 h post clopidogrel 300 mg, and 10 and 28 days following clopidogrel 75 mg daily. A further 55 patients were studied using ADP-induced WBSPC at baseline and 4 h post clopidogrel 600 mg. Patients were genotyped for P2Y12 haplotype and the CYP3A5 6986G > A single nucleotide polymorphism. Neither genotype was found to significantly influence the inhibition of platelet responses by either clopidogrel regimen. In conclusion, common sequence variations within the P2Y12 and CYP3A5 genes do not contribute any major effect to the inter-patient variability in clopidogrel efficacy.

Clopidogrel↗
PubMed1998

Important variables that influence base-line micronucleus frequency in cytokinesis-blocked lymphocytes-a biomarker for DNA damage in human populations.

The cytokinesis-block micronucleus (CBMN) assay has been adopted by numerous laboratories as a means for rapidly assessing base-line chromosome damage (breakage and loss) in human populations. However, the appropriate implementation of this assay requires a thorough understanding of both experimental variables and biological factors that can have impact on micronucleus (MN) frequency. The paper describes, with the help of experimental data the from the author's laboratory as well as other data, the impact of these variables. With regards to experimental variables, the scoring of micronuclei on slides by different technicians has been identified as an important factor; however, the use of different culture media, namely RPMI 1640 and McCoy's medium, did not have a significant effect on base-line frequencies. The paper also describes results showing that the MN index in cytokinesis-blocked cells, measured once every three months over a 12-month period for 53 healthy subjects, remains constant and the data measured on these occasions were significantly and positively correlated (R=0.477 to 0.684, P<0. 0001) with each other thus indicating the reliability and intra-individual variability of the assay over time. Inter-individual variation for males and female subjects has been estimated for each decade of age between 20 and 80 years; the difference between the 25th and 75th percentile of MN frequency varied between 1.4 fold and 2.3 fold and the minimum and maximum values for MN frequency varied by a factor of 4.7 and 12.5 depending on the age group. Age and gender are the most important demographic variables impacting on the MN index with MN frequencies in females being greater than those in males by a factor of 1.2 to 1.6 depending on the age group. For both sexes, MN frequency was significantly and positively correlated with age (R=0.62 in males and R=0.65 in females) and the slope of the regression line in males was 0.314 (P<0.0001) and in females it was 0.517 (P<0.0001). The main dietary factors influencing the MN index in subjects who are not folate deficient are plasma B12 (R=-0.315, P=0.0127) and plasma homocysteine (R=0.415, P=0.0086). In addition, it was proposed that the MN index is likely to be influenced by the propensity of an individual's cells to undergo apoptosis when damaged so that one might expect the MN frequency to be negatively correlated with apoptotic rate although this has yet to be tested. The above indicates the importance of maintaining an international network of scientists working with the CBMN assay to ensure appropriate quality control and for the development of standard experimental and documentation protocols. The human micronucleus (HUMN) project launched in 1997 is briefly described and proposed as the vehicle for these activities.

Adult↗
PubMed2025

The Consortium for Clarity in ADRD Research Through Imaging (CLARiTI): Overview of consortium sites and anticipated enrollment.

INTRODUCTION: The Consortium for Clarity in Alzheimer's disease related dementias (ADRD) Research Through Imaging (CLARiTI) is a study that aims to collect standardized imaging and plasma biomarkers on 2000 Clinical Core participants enrolled across all Alzheimer's Disease Research Centers (ADRC) sites. We sought to summarize the known heterogeneity across centers regarding scientific focus and initial enrollment plans for CLARiTI. METHODS: We developed and distributed a survey capturing information on the 36 CLARiTI site's theme/expertise, recruitment plans, and the intersection of CLARiTI with other ADRC imaging efforts. RESULTS: Anticipated CLARiTI enrollees spanned 11 different categories of suspected etiologies underlying impairment. A wide range of risk factors were endorsed across sites regarding the enrollment of unimpaired individuals. Variability also existed regarding site-level strategies in enrollment into CLARiTI versus other imaging efforts. DISCUSSION: We anticipate that the 2000 individuals that will enroll into CLARiTI will reflect the clinical heterogeneity already in place across the ADRC network. HIGHLIGHTS: The ADRC Consortium for Clarity in ADRD Research Through Imaging (CLARiTI) will leverage and contribute to the existing Alzheimer's Disease Research Centers (ADRC) program by supporting standardized imaging and plasma collection across all centers. We summarize the variation in scientific focus and enrollment plans across ADRC sites participating in CLARiTI. The anticipated CLARiTI cohort will reflect the clinical heterogeneity that already exists across the ADRC network. CLARiTI will contribute to scientific goals related to the detection of multi-etiological signatures relevant for Alzheimer's disease and related disorders (ADRDs).

Humans↗