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At least 613 records · Page 34Linked to original sources

PubMed1998

Physiologic assessment of botulinum toxin effects in the rat larynx.

OBJECTIVE: Botulinum toxin (BT) is a currently used treatment for spasmodic dysphonia (SD) and other related focal dystonias. The goal of this study is to provide a basis for using the rat larynx to objectively assess physiological and histological effects of BT. STUDY DESIGN: Dosages and volumes of BT injection were varied and three physiological parameters were measured. These measures included: optical density of PAS-stained laryngeal muscle after electrical stimulation, which is an indirect measure of denervation, spontaneous laryngeal muscle activity, and laryngeal movement. METHODS: A new microlaryngoscopic technique was developed, which made it possible to observe and manipulate the rat larynx endoscopically. Laryngeal movement and electromyographic (EMG) measures were made prior to injection and 3 days following BT injections of various dosages and volumes. Optical density measures were made 3 days after injection. RESULTS: Significant reductions in vocal fold motion and spontaneous laryngeal muscle activity as a function of increased BT dosage were observed. In addition, the optical density of PAS-stained laryngeal muscle after electrical stimulation was increased following BT injection. Significant volume effects in optical density were observed in the lateral thyroarytenoid and lateral cricoarytenoid muscles on the contralateral side. CONCLUSIONS: The rat laryngeal model is suitable for assessing BT effects. In addition, the three physiological variables provided useful and reliable measures of laryngeal function. It is the authors' intention to use the rat laryngeal model to further examine the physiological and histological effects of BT with the goal of developing new methods for the treatment of patients with SD and other focal dystonias.

Animals↗

PubMed1998

Effort tolerance in elderly women with different physical activity backgrounds.

To study effort tolerance in elderly women with different physical activity backgrounds, 52 physically active (PA) and 42 sedentary control women (CO) aged 66-85 yr were assigned to perform cycle ergometer exercise to their volitional maximum. Oxygen uptake, respiratory exchange ratio (RER), heart rate, work power, and rate pressure product were measured to evaluate the severity of exercise. Plasma C-ANP (C-terminus of the atrial natriuretic peptide prohormone) and plasma N-ANP (N-terminus of the atrial natriuretic peptide prohormone) were analyzed as indicators of cardiac load. Eighty-one percent (N = 42) of the PA and 52% (N = 22) of CO performed the ergometer exercise. The mean peak oxygen uptake was 22.6 and 15.1 mL x kg(-1) x min(-1) among PA and CO, respectively. Twenty-two of the 42 PA and 19 of the 22 CO terminated the ergometer exercise before attaining the objective maximum. The most common reasons for termination were the subject's own wish, abnormal cardiovascular response, or lower limb tiredness. Both C-ANP and N-ANP increased after exercise. The increase in plasma C-ANP correlated significantly with a few physiological variables, whereas comparable associations with N-ANP were not found. It is concluded that inexperience of physical exertion and medical as well as physiological factors limit effort tolerance among elderly women. Differences in the response of C-ANP and N-ANP were found that are suggested to be due to differences in the postsecretory mechanisms between these hormones.

Aged↗

PubMed1997

Haemodynamic responses and population pharmacokinetics of midazolam following administration to ventilated, preterm neonates.

OBJECTIVE: To evaluate the effects of intravenous midazolam on haemodynamic variables and cerebral blood flow velocity (CBFV) and to determine the pharmacokinetics using a population approach in very low birthweight (VLBW) ventilated infants. METHODOLOGY: Physiological variables were measured at predetermined times in 10 infants with birthweight < or = 1500 g following a bolus dose of intravenous midazolam (0.1 mg/kg). Heart rate, mean arterial blood pressure (MAP) and transcutaneous CO2 (TcPCO2) were recorded and CBFV was assessed by Doppler ultrasound. Midazolam concentrations were also measured and pharmacokinetic parameters determined using a population modelling package. RESULTS: No change in heart rate occurred during the study period, while the MAP decreased by 3 mmHg 5 min after midazolam administration compared to baseline values. A non-significant fall in TcPCO2 was seen at 20 min. Mean CBFV decreased from the baseline by 12% at 5 min, then returning to predose values. Midazolam concentrations were in the range shown to be effective in sedation of paediatric intensive care infants with the elimination being delayed in comparison to older children. CONCLUSIONS: As only minor cerebral and haemodynamic effects were found with the use of midazolam in stable ventilated preterm infants, it appears to be a safe, short-term sedative agent.

Analysis of Variance↗

PubMed1988

Epinephrine infusions in patients with social phobia.

To assess the role of peripheral epinephrine in social anxiety, the authors infused 11 patients meeting DSM-III criteria for social phobia with intravenous epinephrine over 60 minutes. Although the mean plasma epinephrine level increased from 113 to 928 pg/ml, only one of the 11 patients experienced observable anxiety; this finding suggests that an increase in plasma epinephrine level alone is inadequate to cause social anxiety. Of the variables measured, only the average minute volume correlated with self-rated anxiety. Ventilatory indexes might be better correlates of subjective anxiety than other physiological variables.

Adult↗

PubMed1999

Physiological and psychological effects of ageing in man.

A cross-sectional study involving men in various age groups was carried out to evaluate some of the physiological and psychological correlates responsible for functional alteration with advancement of age. Each group consisted of 20 soldiers. Their resting physiological variables, lung function parameters, psychophysiological tests, and different mental functions were studied in thermoneutral laboratory. The results revealed the age related decline in various physiological and psychological functions.

Adult↗

PubMed2001

Online pattern recognition in intensive care medicine.

In intensive care physiological variables of the critical-ly ill are measured and recorded in short time intervals. The existing alarm systems based on fixed thresholds produce a large number of false alarms. Usually the change of a variable over time is more informative than one pathological value at a particular time point. Intelligent alarm systems which detect important changes within a physiological time series are needed for suitable bedside decision support. There are various approaches to modeling time-dependent data and also several methodologies for pattern detection in time series. We compare several methodologies de-signed for online detection of measurement artifacts, level changes, and trends for a proper classification of the patient s state by means of a comparative case-study.

Aged↗

PubMed1998

Instrumentation for the remote monitoring of physiological and behavioral variables.

Few commercial products are available for investigators who wish to monitor multiple physiological and behavioral variables in unrestrained subjects. When telemetry is not practical, e.g., in studies of at-sea diving physiology, one of the only options is to design and build a custom data-logging instrument. This paper describes how a data logger was developed for the successful long-term monitoring of dive depth, swim speed, heart rate, water temperature, and multiple body temperatures from free-ranging northern elephant seals. The task was facilitated by using a commercially available single-board computer designed specifically for portable multichannel data acquisition and, where possible, off-the-shelf sensors/transducers available with integrated signal-conditioning circuits. A smaller data logger for monitoring the electrocardiogram, body temperature, and dive behavior of double-crested cormorants is also described to illustrate the flexibility and simplicity of this approach. Although it is customized for diving animals, with incorporation of the appropriate sensors the basic design should be applicable to studies of comparative, environmental, or exercise physiology involving most medium-to-large animals, including humans.

Animals↗

PubMed1989

Thermodynamic network modelling of transfer across the perfused guinea-pig placenta, using SPICE.

The response of the dually perfused guinea pig placenta to bolus inputs of the marker substances 125I-albumin and tritiated water is used to model vascular placental topology and membrane characteristics. This is accomplished by generating a thermodynamic network containing ten adjustable variables describing flow and transfer quantitatively. After translation of the network into an electronic circuit the parameter values are determined with the use of the SPICE program. The results are then used to estimate unknown physiological variables like shunted flow, membrane permeabilities, etc. This model has potential usefulness in the study of those areas of placental physiology in which transient analysis is required.

Albumins↗

PubMed1991

Mortality rates and prognostic variables in children with adult respiratory distress syndrome.

In a retrospective chart review of cases of adult respiratory distress syndrome in our pediatric intensive care unit from 1987 to 1990, we attempted to identify the physiologic variables predictive of death. We identified 44 children with adult respiratory distress syndrome; the mortality rate was 75%. We found significant differences between survivors and nonsurvivors in intrapulmonary venous admixture (Qsp/Qt), mean airway pressure (Paw), alveolar-arterial oxygen tension difference (P(A-a)O2), oxygenation index, and peak inspirator pressure; Qsp/Qt greater than 0.5, Paw greater than 23 cm H2O, and P(A-a)O2 greater than 470 mm Hg were 93%, 90%, and 81% predictive of death, respectively, in this study population. Sensitivity and specificity were enhanced when we linked multiple predictors, but this linkage was seldom successful because few patients had more than one positive predictor. We propose to use the individual predictors that we have identified as randomization criteria in a future trial of extracorporeal membrane oxygenation for pediatric cases of adult respiratory distress syndrome.

Adolescent↗

PubMed1998

[Reactions of young dairy calves and young suckling calves from the mother cow herds to transportation induced stress--effects of age and rearing conditions].

Single box reared dairy calves (TK) and suckler calves (SK) from a mother cow herd were exposed to uniformly performed short-haul road transports. Long lasting measurements by way of heart rate recording, body temperature, body weight and blood sampling before and just after finishing transport and in the morning of next day as well were used assessing the strain and adaptation of calves of 3 to 7 days, of 8 to 15 days and of more than 15 days of postnatal age. Blood samples were analyzed for acid base balance, gas content, haemoglobin derivatives and haemoglobin variants, protein, metabolites, minerals and cortisol. Different mean values between age groups and sampling points could be found for heart rate, body temperature, pCO2, BE, HCO3, total protein, creatinine, blood urea, glucose, lactate, cortisol, methaemoglobin, Mg, Ca, P. In suckler calves heart rate, body temperature, total protein, P and fraction of MetHb were higher and creatinine, lactate and cortisol were lower than in dairy calves. Different means between sampling points existed for heart rate, cortisol, body temperature except SK > 15 days, lactate except SK 8-15 days and glucose except TK 3-7 and TK 8-15 days. Results show relative intensity and degree of strain imposed to young calves in case of transport, the preferentially affected variables and the importance of time factors (age of animals, infradian rhythmicity, relationship between the start of a reaction and concentration changes in body fluids) for the change of physiological variables of young animals exposed to transport.

Aging↗

PubMedDate not supplied

The effect of chest wall transcutaneous electrical nerve stimulation on dyspnoea.

We studied the effects of transcutaneous electrical nerve stimulation (TENS) over the chest wall on breathlessness in normal subjects during exercise. Eleven male subjects performed a progressive incremental exercise test to break point on four consecutive days. TENS (continuous form, frequency 100 Hz, pulse width 200 microseconds) was applied during three of these tests-over the second intercostal spaces during inspiration ('in phase' with the underlying inspiratory muscle contraction) or expiration ('out of phase' with contraction) or over the deltoid muscles during inspiration (control), and not on the fourth occasion in random order. Breathlessness (Borg scale), heart rate, respiratory frequency, tidal volume, minute ventilation and minute oxygen uptake were measured. No significant differences were found for any of the measured variables between the four study days. We conclude that TENS under these circumstances has no effect on the sensation of breathlessness or on the measured physiological variables in normal subjects during exercise.

Adult↗

PubMed1989

Physical performance during combinations of hypercapnic, resistive, and hot air breathing.

Performance time for a 3.2-km (2-mi) run at maximal voluntary speed was determined for 12 subjects under seven experimental conditions: resistance breathing (R), hypercapnia (C), hot air breathing (H), and combinations R + C, R + H, H + C, and R + H + C. The tests were performed on a treadmill at 5% grade. Performance time was increased significantly when the subjects were exposed to resistance breathing alone (9%) or to any combination condition containing resistance (16%-31%). The effect of breathing resistance was not specific to the presence or absence of C, H, or their combination. Nevertheless, the physiological effects were not additive and could not be predicted by knowing the effects of the individual stresses. Performance time also was increased in Condition H + C (9%). Pulmonary ventilation was the most affected physiological variable, significantly reduced in Conditions R, H, C + R, H + R, and H + C + R. In conclusion, a multistress approach should be used when determining physiological responses or performance limitations brought about by real or simulated industrial respirator-wear conditions.

Adult↗

PubMed1986

Physiology of the circadian timing system: predictive versus reactive homeostasis.

Since Cannon first formulated the concept of homeostasis 60 years ago, attention has been focused on the corrective responses initiated after the steady state of the organism is perturbed. In this lecture it is argued that the concept of homeostasis should be extended to include the precisely timed mechanisms of the circadian (and circannual) timing system which enables organisms to predict when environmental challenges are most likely to occur. A mature understanding of homeostasis should encompass both "reactive" responses to changes in physiological variables which have already occurred and the "predictive" responses initiated in anticipation of predictably timed challenges. Such predictive responses have particular value because they enable physiological mechanisms to be utilized immediately, even if they involve a delay of several hours, by activating them at a suitable time in advance of a probable challenge. However, conflicts may often occur between predictions and reality. Examples from sleep-wake behavior, thermoregulation, blood volume homeostasis, and the regulation of potassium balance show that predictive responses often compromise the effectiveness of reactive homeostatic mechanisms even to the point of risking the survival of the organism. It must be concluded that the day-night cycle of the natural environment has played a fundamental role in shaping the evolutionary development of homeostatic mechanisms because of the dominating predictability of diurnal changes in illumination, temperature, food availability, and predator activity.

Animals↗

PubMed1995

[Reference values for trace elements in biological fluids].

The assessment of reliable reference ranges for the concentrations of elements in biological fluids is necessary to evaluate the risks deriving from occupational and environmental exposure. For the production of reference ranges in this field it is necessary to adhere to strict criteria for the selection of individuals, the procedures for sample collection, the control of analytical variability and the statistical treatment of results. The factors affecting analytical and biological variability of the concentrations to be determined, such as the route of absorption, the presence of sources of environmental pollution in certain areas of residence, physiological variables and life-styles, are discussed.

Animals↗

PubMed1984

Circadian rhythm of blood pressure in patients dependent on ventricular demand pacemakers.

The reported circadian rhythm of blood pressure variability with a rise in pressure before awakening has been the subject of controversy. Previous studies have suggested that since heart rate continues to fall before awakening while blood pressure is rising these physiological variables are subject to different control mechanisms. To evaluate further the dissociation of heart rate and blood pressure changes in a group of patients with a fixed heart rate, 11 patients who were dependent on ventricular demand pacemakers underwent intra-arterial ambulatory blood pressure monitoring. Nine aged matched control subjects followed the same protocol. Circadian curves plotted from pooled hourly mean data showed that despite a fixed heart rate the circadian pattern persisted, although attenuated, with blood pressure rising several hours before its rapid rise on awakening. Physiological testing showed that despite a fixed heart rate systolic blood pressure rose in response to bicycle exercise, there was a postural fall in the blood pressure on tilting and a modified Valsalva response. There was considerable beat to beat variability resulting presumably from asychronous pacing. Hour to hour changes did not contribute to the differences between the two groups and were not responsible for attenuation of the circadian rhythm. It is concluded that blood pressure and heart rate control mechanisms may be dissociated, particularly in the period before awakening.

Aged↗

PubMedDate not supplied

The fatigue experience for women with human immunodeficiency virus.

PURPOSE: To examine fatigue as a symptom experienced by women with human immunodeficiency virus (HIV). SAMPLE: A convenience sample of 100 women with HIV. ANALYSIS: Independent sample t-tests were used to test for mean differences in fatigue related to variables in the women's sociocultural and home environment (ethnicity, employment, marital status, and parenting). Pearson product moment correlations were used to examine significant relationships between fatigue and physiologic variables (age, CD4 cell count, and sleep). FINDINGS: Lower CD4 cell counts were related to more daytime sleep, higher evening fatigue, and higher morning fatigue. Morning fatigue was related to duration of wake episodes during the night, napping, and perception of sleep disturbance during the past week. The number of awakenings during the first night predicted the severity of fatigue the next evening. CONCLUSION: To understand the fatigue experienced by women with HIV, researchers and clinicians must focus on the relative contributions of sociocultural, home, and physiologic environments within which these women live. Additional research is ongoing to identify the strategies these women use to manage daily activities such that gender-relevant and culturally relevant interventions for alleviating fatigue can be tested in women with a variety of chronic illnesses, including HIV and acquired immune deficiency syndrome.

Adult↗

PubMed2000

Fluvoxamine reduces physiologic reactivity to trauma scripts in posttraumatic stress disorder.

This study assessed the effect of open-label fluvoxamine treatment for posttraumatic stress disorder (PTSD), depressive symptoms, and physiologic arousal to trauma cues. Baseline psychometric ratings and physiologic assessments of heart rate and blood pressure responses to individualized, taped trauma scripts were determined for 16 patients with PTSD and 16 mentally healthy age- and gender-matched control subjects exposed to at least 1 serious trauma. Patients with PTSD had greater autonomic reactivity than control subjects at baseline, with physiologic measures correlating with the severity of the PTSD for the combined groups. Discriminant analyses indicated that systolic blood pressure best classified patients with PTSD (75% sensitivity) and control subjects (100% specificity), with a stepwise discriminant analysis showing that combined physiologic variables correctly classified 75% of patients with PTSD and 100% of control subjects. After 10 weeks of fluvoxamine treatment (100-300 mg/day), patients' PTSD, depression, and physiologic reactivity improved significantly. Medicated patients with PTSD could not be distinguished statistically from untreated control subjects in any physiologic measure. This dampening of autonomic reactivity after drug treatment corroborates subjective measures of improvement, validating the reported efficacy of fluvoxamine in this open trial.

Adult↗

PubMed1980

Pharmacological screening of new chemical entities in human subjects and methods of data handling.

1 A system is described for screening new chemical entities in normal human subjects, which is designed to search for novel drug actions at an early stage of drug development. 2 In single (subject) blind experiments, doses are increased incrementally from one subject to next, with immediate feed-back of results from each dose. 3 As many physiological variables as possible are recorded, for which a purpose-designed apparatus system was constructed, and connected to a computer. 4 To overcome problems of inter-subject variability, the need for sensitivity, and to identify drug-related effects from the mass of data generated, a novel data management system was developed, and physiological profiles of volunteer subjects were built up to provide control data. 5 Results from a validation experiment in which isoprenaline was infused intravenously at different rates are presented and discussed.

Dose-Response Relationship, Drug↗