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Results for “physiologic variables”

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PubMed1996

Can tremor be used to measure the effect of chronic mercury exposure in human subjects?

Clinical and quantitative studies in which tremor was used to evaluate the effect of chronic exposure to organic and inorganic mercury in human subjects during the last 20 years were identified in MEDLINE and BIOLOGICAL ABSTRACTS. In the selected studies, methods varied widely by types of transducers used, anatomical locations of tremor testing, tasks executed by the subjects, types of tremor recorded and durations of trials. Measurements of tremor in these studies also varied by frequency, amplitude, waveform and reproducibility. Typically measures of variability were not included. Results obtained depended heavily on the methods and analyses used. We suggest that, although many contradictions and discrepancies have been noted in these studies, tremor can probably be used to measure the effect of chronic mercury exposure. This would involve more rigorous and uniform recording procedures and analyses. Specific suggestions proposed include: realizing the limitations of accelerometric data; considering the effect of weight on the tested limb; controlling recording conditions; selecting samples more carefully; recording other physiological variables besides tremor; using tasks and manoeuvres that unmask subclinical abnormalities in tremor; reporting frequency, amplitude, waveform and variability of tremor; understanding the limitations of power spectra analysis; separating tremor characteristics according to types of mercury exposure; and considering supraspinal influences that both vision and voluntary movements have on tremor.

Environmental Exposure↗

PubMed1994

Longitudinal development of young talented speed skaters: physiological and anthropometric aspects.

A longitudinal analysis of a group of speed skaters was done to identify the performance-determining factors for a successful speed skating career. This paper presents both the physiological and anthropometric results of this longitudinal study. Twenty-four athletes from the Dutch National Junior Speed Skating Team were followed from age 16-17 yr to age 20-21 yr. During the development from junior to senior speed skater, a number of anthropometric and physiological variables changed. There were no differences between successful and unsuccessful speed skaters from an anthropometric perspective; consequently, it was not possible to distinguish successful from unsuccessful athletes on anthropometric grounds. The longitudinal data showed that at a younger age the successful speed skaters had similar oxygen consumption, mechanical efficiency, and power output values compared with the unsuccessful speed skaters. Later in the study, successful speed skaters distinguished themselves by the ability to produce higher power output values. There were no anthropometric or physiological relationships found in this study on which performance at the age of 20-21 yr could be predicted with measurements at a junior age.

Adolescent↗

PubMed1990

Computer-based sleep monitoring in SIDS-risk infants--preliminary results.

A computerized, PC-based system is introduced for sleep monitoring in infants. The system is capable of digitizing and storing 22 physiological variables over a whole-night sleep period. The preprocessed data can be displayed on a single page; further processing can be done on the digitally stored data.

Computer Systems↗

PubMed2004

Screening for retinopathy of prematurity: is it painful?

BACKGROUND: Screening programmes for retinopathy of prematurity have shown to reduce unfavourable visual outcome and to be cost-effective. Following present recommendations, almost 1% of all newborn babies should therefore be screened and undergo at least one ophthalmologic examination. This is a skilled procedure that requires drug instillation and manipulation of the ocular globe with scleral indentation. The objective of this study is to describe the side effects of this ophthalmic exam with special focus on the occurrence of pain. METHODS: This was an observational study with a before-after analysis where all neonates undergoing an ophthalmologic exam during a 4-month period in a third level hospital were included. CRIES pain score was determined before the exam, 5 min after and 24 h after the screening manoeuvre. Blood pressure and pulse rate were determined in addition to the mentioned measurements 30 min after the ophthalmologic examination. Minimum oxygen saturation, apnoeas, gastrointestinal side effects (like vomiting and gastric aspirates), the need for respiratory assistance or for intensive care unit admission were recorded within 24 h before and after the procedure. RESULTS: 27 preterm neonates underwent an ophthalmologic examination and were included in the study. CRIES pain score was significantly higher 5 min after and 24 h after the screening procedure than before. This difference was also observed after stratification for birth weight and gestational age. No other study variable modified this time effect. No significant changes in blood pressure and pulse rate were shown after the ophthalmic exam. Vomiting was present in 4% of the newborns, gastric aspirates in 22% and apnoeas in 41% after the examination. Ten percent of the explored preterm babies needed increased respiratory assistance and 4% had to be transferred from the intermediate care unit to the intensive care because of severe apnoeas. COMMENTS: An increase in pain score was shown after retinopathy of prematurity screening examination. Physiologic variable changes do not last long enough to evaluate the impact of certain procedures. Multivariate pain scores (like CRIES) should be used in everyday practice. It seems that the ophthalmologic examination in preterm babies might be painful and further studies should identify the best strategy to prevent pain during the retinopathy of prematurity screening manoeuvre.

Apnea↗

PubMedDate not supplied

Psychosocial coping strategies and cardiac capacity before and after coronary artery bypass surgery.

One hundred patients, eighty-nine men and eleven women, with chronic stable angina who were previously selected for aortocoronary bypass grafting gave informed consent for non-invasive and invasive testing of hemodynamic responses to symptom-limited maximal exercise before surgery. Psychosocial coping strategies were evaluated preoperatively by structured interviews and assessment of patients perceptions of symptoms (Cornell Medical Index) and life changes (Holmes and Rahe Schedule of Recent Experiences). Preoperatively forty-one patients were "compartmentalized," forty-two "generalized" and seventeen "vacillated" according to Josten's classification of coping strategies. The Berle Index of social assets was lower and the prevalence of psychiatric symptoms (Cornell categories M to R) was greater in the vacillators preoperatively. Despite less ischemic ST depression in vacillators, no other significant physiological differences were noted between these categories preoperatively. Postoperatively more of the vacillators refused follow-up evaluation, and of vacillators who returned, only one-half were adequately revascularized at operation. Of sixty-five reevaluated after surgery, eight improved, twelve worsened and forty-five did not change classification of coping strategies, yet physiological variables of cardiac function when invasively measured in sixty patients were significantly improved in all three groups. Amounts of improvement, both absolutely and relative to sex- and age-adjusted normal values, were least in vacillators with virtually normal cardiac capacity, and/or inadequate revascularization. Compartmentalized patients were more frequently working, yet only sixty-four in all psychosocial classifications worked before surgery. After this event only forty-five resumed working; none of the non-workers or retired returned to work. Both physiologic improvement and working status were independent of postoperative psychosocial status.

Adaptation, Psychological↗

PubMed2002

Pulmonary dead-space fraction as a risk factor for death in the acute respiratory distress syndrome.

BACKGROUND: No single pulmonary-specific variable, including the severity of hypoxemia, has been found to predict the risk of death independently when measured early in the course of the acute respiratory distress syndrome. Because an increase in the pulmonary dead-space fraction has been described in observational studies of the syndrome, we systematically measured the dead-space fraction early in the course of the illness and evaluated its potential association with the risk of death. METHODS: The dead-space fraction was prospectively measured in 179 intubated patients, a mean (+/-SD) of 10.9+/-7.4 hours after the acute respiratory distress syndrome had developed. Additional clinical and physiological variables were analyzed with the use of multiple logistic regression. The study outcome was mortality before hospital discharge. RESULTS: The mean dead-space fraction was markedly elevated (0.58+/-0.09) early in the course of the acute respiratory distress syndrome and was higher among patients who died than among those who survived (0.63+/-0.10 vs. 0.54+/-0.09, P<0.001). The dead-space fraction was an independent risk factor for death: for every 0.05 increase, the odds of death increased by 45 percent (odds ratio, 1.45; 95 percent confidence interval, 1.15 to 1.83; P=0.002). The only other independent predictors of an increased risk of death were the Simplified Acute Physiology Score II, an indicator of the severity of illness (odds ratio, 1.06; 95 percent confidence interval, 1.03 to 1.08; P<0.001) and quasistatic respiratory compliance (odds ratio, 1.06; 95 percent confidence interval, 1.01 to 1.10; P=0.01). CONCLUSIONS: Increased dead-space fraction is a feature of the early phase of the acute respiratory distress syndrome. Elevated values are associated with an increased risk of death.

Acquired Immunodeficiency Syndrome↗

PubMed2004

Variability of thyroid blood flow Doppler parameters in healthy women.

The purpose of this study was to estimate variability of flow Doppler parameters in the superior thyroid artery (STHA) during the menstrual cycle in young women and to explore the influence of endogenous 17-b-estradiol (E2) and progesterone (PRG) on the velocity waveform. The plasma concentration of these hormones was correlated with flow velocities, pulsatility index (PUI), resistance index (RI) and acceleration index (accI) and time (accT), which were measured with color-coded duplex sonography 8 times during the cycle in 14 healthy women (age range: 23 to 25 years). Coefficient of variation (CV), interclass correlation (ICC), repeatability (repC) and pooled Pearson correlation (r) coefficients were used to estimate the variability of the parameters. The highest variability was found for accI and accT: CV = 48% and 31%; ICC = 0.51 and 0.45; repC = 2.8 and 95; r = 0.37 and 0.4, respectively. The CV for flow velocities varied from 25% to 26%, ICC from 0.53 to 0.56, repC from 8 to 17 and r has a value of 0.46. The respective values for RI and PUI were: 11%, 18%; 0.48, 0.55; 0.15, 0.48; and 0.46, 0.48. The diastolic blood pressure decreased significantly by 7 mmHg (p < 0.01) in the luteal phase, whereas other physiological variables were stable during the cycle. Although the fluctuations of the flow parameters during the cycle were not statistically significant, a weak linear correlation between flow velocities and concentration of E2 was found; for mean velocity r = 0.16, p < 0.05. Impedance indices showed an increasing trend in the luteal phase, along with increase of the pulse pressure index (PPI). The results showed that variability of the flow parameters in the STHA is substantial and that higher flow velocities are associated with increase of plasma concentration of 17-b-estradiol during the menstrual cycle in young women.

Adult↗

PubMedDate not supplied

Myocardial infarction in the C57BL/6J mouse: a quantifiable and highly reproducible experimental model.

INTRODUCTION: The laboratory mouse is a powerful tool in cardiovascular research. In this report, we describe a method for a reproducible mouse myocardial infarction model that would allow subsequent comparative and quantitative studies on molecular and pathophysiological variables. METHODS: (A) The distribution of the major coronary arteries including the septal artery in the left ventricle of the C57BL/6J mice (n=20) was mapped by perfusion of latex dye or fluorescent beads through the aorta. (B) The territory of myocardial infarction after the ligation of the most proximal aspect of the left anterior descending (LAD) coronary artery was quantified. (C) The consistency in the histological changes parallel to the infarction at different time points was analyzed. RESULTS: (A) The coronary artery tree of the mouse is different from human and, particularly, in regard to the blood supply of the septum. (B) Contrary to previous belief, the septal coronary artery in the mouse is variable in origin. (C) A constant ligation of the LAD immediately below the left auricular level ensures a statistically significant reproducible infarct size. (D) The ischemic changes can be monitored at a histological level in a way similar to what is described in the human. CONCLUSION: We illustrate a method for maximal reproducibility of experimental acute myocardial infarction in the mouse model, due to a consistent loss of perfusion in the lower half of the left ventricle. This will allow the study of molecular and physiological variables in a controlled and quantifiable experimental model environment.

Animals↗

PubMedDate not supplied

Pitfalls in oncologic diagnosis with FDG PET imaging: physiologic and benign variants.

A rapidly emerging clinical application of positron emission tomography (PET) is the detection and staging of cancer with the glucose analogue tracer 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG). Proper interpretation of FDG PET images requires knowledge of the normal physiologic distribution of the tracer, frequently encountered physiologic variants, and benign pathologic causes of FDG uptake that can be confused with a malignant neoplasm. One hour after intravenous administration, high FDG activity is present in the brain, the myocardium, and--due to the excretory route--the urinary tract. Elsewhere, tracer activity is typically low, a fact that allows sensitive demonstration of tracer accumulation in many malignant neoplasms. Interpretive pitfalls commonly encountered on FDG PET images of the body obtained 1 hour after tracer administration can be mistaken for cancer. Such pitfalls include variable physiologic FDG uptake in the digestive tract, thyroid gland, skeletal muscle, myocardium, bone marrow, and genitourinary tract and benign pathologic FDG uptake in healing bone, lymph nodes, joints, sites of infection, and cases of regional response to infection and aseptic inflammatory response. In many instances, these physiologic variants and benign pathologic causes of FDG uptake can be specifically recognized and properly categorized; in other instances, such as the lymph node response to inflammation or infection, focal FDG uptake is nonspecific.

Diagnosis, Differential↗

PubMed1987

Emotional and physiological effects of nitrous oxide and hyperbaric air narcosis.

Measurements of seven self-reported emotional states (happiness, activity, fear, anger, depression, fatigue, and anxiety) and three physiological variables (heart rate, systolic blood pressure, and diastolic blood pressure) were made among 16 subjects under four conditions: all subjects breathing normobaric air; several days later, immediately after half the subjects had breathed 30% nitrous oxide and the other half had breathed nomobaric air; the following day, subsequent to exposure of all subjects to a simulated depth of 57 m on air in a hyperbaric chamber; and several weeks after the hyperbaric chamber exposure, with all subjects breathing nomobaric air. The results showed that the physiological responses of the group that breathed nitrous oxide did not differ significantly from the control group following the hyperbaric chamber exposure, while self-reported happiness was lower among the nitrous oxide group than among the control group following hyperbaric chamber exposure. Nitrous oxide does not appear to benefit emotional or physiological adaptation to nitrogen narcosis associated with breathing hyperbaric air, and may even impair emotional adaptation, at least under these experimental conditions.

Adult↗

PubMed1991

The measurement of psychophysiological reactions of pilots to a stressor in a flight simulator.

Seventeen Boeing 737 pilots were exposed to an acute stressor in a flight simulator: a birdstrike between V1 (velocity of aircraft on take-off run at which crew is committed to take-off regardless of any incidents occurring) and VR (velocity of aircraft at take-off). Certain physiological variables together with state anxiety scores were measured at different stages of the simulated flight. Levels of plasma cortisol, norepinephrine, total protein, total lipid, lactate, and the haematocrit changed significantly across the test conditions. Plasma epinephrine, osmolality and glucose levels did not change significantly across the test conditions. Captains and copilots differed significantly in the profiles obtained for the state anxiety scores. The variables measured in this study demonstrated different profiles in response to the stressor. Conceptual and methodological problems need to be solved before an integrated psychophysiological approach to the reactions of pilots to stressors can be developed.

Adult↗

PubMed1997

Objective predictors of response for staple versus laser emphysematous lung reduction.

Recently described surgical approaches to the treatment of emphysema, including buttressed stapled volume reduction and laser coagulation, are associated with variable clinical outcomes. We examined objective preoperative factors as predictors of response to treatment in patients enrolled in a randomized trial of staple versus laser volume-reduction surgery in order to help define patient selection criteria for these procedures. Seventy-two patients with severe symptomatic emphysema without bullae were entered into the protocol (39 staple, 33 laser). Preoperative objective variables (pulmonary function tests, smoking history, demographics, and graded chest computed tomographic [CT] scans) were evaluated as predictors of response to treatment (defined as a change in FEV1) at 3- to 6-mo follow-up, using linear and multivariate regression analysis. Follow-up pulmonary function was obtained on 90% of the 68 patients surviving at 6 mo. Overall improvement was significant only for staple-treated patients, and improved outcome correlated with greater smoking history and younger age for staple-treated patients. When physiologic variables were analyzed, greater smoking history, lower DL(CO), and younger age predicted improved outcome for laser-treated patients. Preoperative FEV1 and gas-exchange variables did not predict outcome in staple-treated patients. When CT scan grading was included in multivariate regression analysis, hyperinflation (increased thoracic gas volume) was the primary predictor of response for laser-treated patients. These findings suggest that younger patients with evidence of advanced emphysematous lung disease and hyperinflation are optimal candidates for lung-volume-reduction surgery, particularly by staple-reduction techniques. Additional studies with long-term follow-up, bilateral procedures, and assessment of other outcome measures must be performed to further define operative criteria for lung-volume-reduction surgery for emphysema.

Age Factors↗

PubMed1987

Interindividual variability of lithium-induced EEG changes in healthy volunteers.

A placebo-controlled, double-blind study on the effects of lithium on the electroencephalogram (EEG) was performed in 20 healthy volunteers. A reanalysis of the data which previously had been evaluated by factor analysis and other techniques is presented. The aim of this reanalysis is a quantitative reconstruction of visually defined vigilance stages. In 8 of the 10 healthy subjects who received lithium, a "stabilization" of vigilance on a slightly lowered level (i.e., increased continuity of alpha activity and a tendency in the direction of increased alpha anteriorization) could be demonstrated after a 2-week medication period (mean lithium plasma level: 0.65 mmol/l), indicating that in these subjects lithium counteracts the physiological decline of vigilance to be expected under resting conditions. The interpretation of this finding as a reduction of physiological variability, or as a "dynamic restriction," corresponds to findings in other areas of lithium research which can be interpreted in an analogous manner. In two subjects, however, a small decline of vigilance was observed. These two subjects showed an especially pronounced alpha rhythm in their predrug EEG compared with the other volunteers. The authors discuss whether the delineation of different EEG reaction types contributes to the responder problem in lithium research.

Adult↗

PubMed2002

A database of [(11)C]WAY-100635 binding to 5-HT(1A) receptors in normal male volunteers: normative data and relationship to methodological, demographic, physiological, and behavioral variables.

PET studies of [(11)C]WAY-100635 binding are proving to be a useful tool to evaluate 5-HT(1A) receptor function in vivo in humans. We describe the pattern of [(11)C]WAY-100635 binding in 61 healthy male brains and examine its variability. For all PET scans, binding potential (BP) values for [(11)C]WAY-100635 in different regions were calculated using a simplified reference tissue model, with the cerebellum as reference region. Specifically we describe (1) region of interest and SPM databases of PET [(11)C]WAY-100635 binding, including test-retest variability; (2) the sensitivity of [(11)C]WAY-100635 binding to manipulations of endogenous 5-HT; and (3) correlations between [(11)C]WAY-100635 binding and radiochemical, demographic, physiological, and behavioral variables. The regional distribution of [(11)C]WAY-100635 binding in healthy human brain was similar to that reported in vitro. The test-retest variability was approximately 12% (range 9-16%) and was similar for all methods of regional sampling. The binding of [(11)C]WAY-100635 was insensitive to changes in brain 5-HT induced by tryptophan infusion and depletion. Although BP values varied greatly across subjects (range 2.9-6.8), there were no significant correlations of regional and global BP with common radiochemical, demographic, physiological, and personality variables. Specifically, in contrast with two recent small studies, we found no decline of [(11)C]WAY-100635 binding with age in our large cohort over the age range of 24 to 53 years. Assessment of 5-HT(1A) receptors in vivo using PET and [(11)C]WAY-100635 gives reliable measures of 5-HT(1A) binding. The large between-subject variability observed could not be explained by common methodological, physiological, or behavioral factors and hence the biological basis of this variability remains to be clarified.

Adult↗

PubMed2001

Environmental and physiological factors affecting lead and cadmium levels in deciduous teeth.

Shed deciduous teeth lead and cadmium content of children from Cartagena (Spain) was assessed. Parents were provided with an interview containing different questions concerning family socioeconomic status, child's health history, zone of residence, or home antiquity. Besides, physiological variables were considered, i.e., sex of donor, presence of caries, type of tooth donated, tooth weight, age of shedding, and position within the mouth. Tooth lead and cadmium data showed a positively skewed distribution and were log-normalized for further analyses. No statistically significant differences could be observed for lead and cadmium values according to the sex of donor. Both heavy metals decreased in content from incisors to molars and with age of shedding. The one-way analysis of variance (ANOVA) displayed both environmental and physiological risk factors contributing to high tooth lead and cadmium values. When a multifactor ANOVA was carried out, the associations between home antiquity, nail biting habit, and jaw with tooth lead levels, as well as those between zone of residence and tooth cadmium levels were found to persist. However, the only common factor for both heavy metals in the multiple analyses was the type of tooth.

Cadmium↗

PubMed1984

Effects of naloxone on exercise performance.

This study was designed to investigate the effects of naloxone on athletic performance in humans. Two groups of elite middle-distance runners performed a maximal or a submaximal exercise protocol following the double-blind intravenous injection of either naloxone (0.15 mg X kg body wt-1) or saline. The maximal test (group M) was comprised of a short-duration treadmill run to maximal intensity; the submaximal test (group S), a prolonged submaximal treadmill run to exhaustion. O2 uptake, heart rate, ventilation, and perceived exertion were determined during each test. Perception of pain was assessed after exercise by use of a modified McGill pain questionnaire. No significant differences between placebo and naloxone treatments were found in any of the measured variables at the usually accepted 5% (P = 0.05) confidence level; however, evidence suggesting differences (i.e., P = 0.1 to 0.05) in these important respects was observed. In group M, maximal exercise performance measured by maximal O2 consumption was not different between placebo and naloxone; results suggest that VE was increased (P = 0.08) following naloxone, but only at the final work stage. In group S, exercise performance time was reduced following naloxone (P = 0.09), whereas the affective component of pain was increased (P = 0.06); no differences in the measured physiological variables were observed. These results suggest the following: 1) the opiate receptor-endorphin system may alter the perception of pain associated with prolonged high-intensity submaximal exercise with a resultant significant effect on performance; and 2) it may play a role in the control of ventilation during maximal exercise.

Adolescent↗

PubMedDate not supplied

EEMCO guidance to the in vivo assessment of tensile functional properties of the skin. Part 1: relevance to the structures and ageing of the skin and subcutaneous tissues.

From an engineering point of view, the skin and subcutaneous tissue represent an integrated load-transmitting structure. It is subjected to intrinsic and environmental influences. An attempt to use a four-layered model is offered to explain how the integument withstands and transmits loads through deforming appropriately. The stratum corneum, the association between the living epidermis and papillary dermis, the reticular dermis and the hypodermis have each their own intimate structures whose tensile functions are ideally balanced to respond adequately to the casual mechanical demands. A series of physiological variables, ageing and skin diseases alter the tensile functions of the organ. In the overall analysis, truly comprehensive multidisciplinary approaches in this field have brought advances in the understanding of functional skin biology. The assessment of tensile functions of skin also provides incentives for progress in skin care.

Aging↗

PubMed2006

[Psychophysiologic disturbances in early postmenopause in women after physiological and surgical menopause].

BACKGROUND/AIM: The most common secondary manifestations of menopause are clinical manifestations of estrogen deficiency. They could be early and late. The aim of this study was to compare manifestations of somatic disturbances in early postmenopause in women after physiological and surgical menopause. METHODS: This prospective study included 60 women, age 41-55 years, divided into two groups: physiological (30 of them) and surgically induced menopause. For every subject a special evidence list, consisting of the disease history questions, physical and gynecology examination as well as dates about physiological variables (arterial tension, height, weight, and body-mass index) and laboratory examination was formed. The values of arteriol blood pressure, body height, body mass, body mass index (BMI), and lipid status were determined and gynecological examinations were performed in each patient. RESULTS: The most frequent symptoms in both groups were vasomotor ones. Headache was the more intensive sign in the group after induced menopause. Extrasistolyc heart excursion was a common symptom in both study groups. Arterial tension, regardless of the type of menopause, was in the physiological range. The frequent organic signs of menopause, more intensive in the group after induced menopause, were genitourinary and skin atrophy. An analysis of the BMI showed that the women in both groups were obese (BMI > 25). The lipids analysis confirmed the predomination of hyperlipoproteinemia type IIa in the group with physiologic menopause and type IIb after induced menopause. CONCLUSION: The dominant signs of menopausal syndrome were vasomotor and bone-joint symptoms, more frequent in the group after induced menopause. There were no statistically significant differences between the study groups according to the genitourinary atrophy and other signs of aging. Menopausal hormonal changes, regardless of the way of menopause developing, increase the risk for hyperlipoproteinemia. The frequency of somatic signs in early post menopause is typically higher after induced menopause. More intensive follow-up in patients after surgical removing of the ovaria is necessary in order to improve the quality of life in these patients.

Adult↗