Deep breath reversal and exponential return of methacholine-induced obstruction in asthmatic and nonasthmatic subjects

2004 ◽  
Vol 96 (1) ◽  
pp. 137-142 ◽  
Author(s):  
Andrew C. Jackson ◽  
Margaret M. Murphy ◽  
John Rassulo ◽  
Bartolome R. Celli ◽  
Roland H. Ingram
Keyword(s):  
Healthy Subjects ◽  
Time Course ◽  
Rapid Decrease ◽  
Airway Wall ◽  
Methacholine Challenge ◽  
Order Process ◽  
Deep Breath ◽  
First Order ◽  
Before And After ◽  
Complete Reversal

A deep breath (DB) during induced obstruction results in a transient reversal with a return to pre-DB levels in both asthmatic and nonasthmatic subjects. The time course of this transient recovery has been reported to be exponential by one group but linear by another group. In the present study, we estimated airway resistance (Raw) from measurements of respiratory system transfer impedance before and after a DB. Nine healthy subjects and nine asthmatic subjects were studied at their maximum response during a methacholine challenge. In all subjects, the DB resulted in a rapid decrease in Raw, which then returned to pre-DB levels. This recovery was well fit with a monoexponential function in both groups, and the time constant was significantly smaller in the asthmatic than the nonasthmatic subjects (11.6 ± 5.0 and 35.1 ± 15.9 s, respectively). Obstruction was completely reversed in the nonasthmatic subjects (pre- and postchallenge mean Raw immediately after the DB were 2.03 ± 0.66 and 2.06 ± 0.68 cmH2O·l-1·s, respectively), whereas in the asthmatic subjects complete reversal did not occur (2.29 ± 0.78 and 4.84 ± 2.64 cmH2O·l-1·s, respectively). Raw after the DB returned to postchallenge, pre-DB values in the nonasthmatic subjects (3.78 ± 1.56 and 3.97 ± 1.63 cmH2O·l-1·s, respectively), whereas in the asthmatic subjects it was higher but not significantly so (9.19 ± 4.95 and 7.14 ± 3.56 cmH2O·l-1·s, respectively). The monoexponential recovery suggests a first-order process such as airway wall-parenchymal tissue interdependence or renewed constriction of airway smooth muscle.

Effect of thiol oxidation and thiol export from erythrocytes on determination of redox status of homocysteine and other thiols in plasma from healthy subjects and patients with cerebral infarction

1995 ◽  
Vol 41 (3) ◽  
pp. 361-366 ◽  
Author(s):  
A Andersson ◽  
A Lindgren ◽  
B Hultberg
Keyword(s):  
Cerebral Infarction ◽  
Healthy Subjects ◽  
Redox Status ◽  
Reduced Form ◽  
Temperature Dependent ◽  
First Order ◽  
First Order Kinetics ◽  
Before And After ◽  
Reduced Forms

Abstract Changes in concentration of reduced and oxidized low-M(r) thiols were measured in blood and plasma before and after the separation of blood cells. If centrifugation of blood was postponed, the reduced form of homocysteine in plasma increased with time at 22 degrees C; in contrast, the concentrations of other reduced thiols (cysteine, glutathione, and cysteinylglycine) decreased. In plasma the reduced forms of all thiols disappeared at a rate that followed first-order kinetics. The rates of disappearance ("half-lives") were temperature-dependent; they were about the same for glutathione and homocysteine (11.7 and 14.3 min, respectively, at 22 degrees C) and somewhat higher for cysteinylglycine and cysteine. After establishing proper sampling conditions for reduced thiols, we measured this thiol fraction as well as free (non-protein-bound) and total thiols in 10 reference subjects and 19 patients with cerebral infarction. Mild but significant hyperhomocysteinemia involving total and free homocysteine (but not reduced homocysteine) was found in the patients.

Modulation of gastric motor activity by a centrally acting stimulus, circular vection, in humans

2001 ◽  
Vol 280 (5) ◽  
pp. G850-G857 ◽  
Author(s):  
Henryk Faas ◽  
Christine Feinle ◽  
Paul Enck ◽  
David Grundy ◽  
Peter Boesiger
Keyword(s):  
Gastric Emptying ◽  
Healthy Subjects ◽  
Time Course ◽  
Delayed Gastric Emptying ◽  
Contractile Activity ◽  
Subjective Symptom ◽  
Gastric Volume ◽  
Rapid Decrease ◽  
Resonance Imaging ◽  
Baseline Activity

The aims of this study were to investigate gastric motor correlates of vection, a centrally acting stimulus, and relate these responses to the induction of motion sickness symptoms. Antral contractile activity and gastric volume retained after a liquid nutrient meal (600 ml) were assessed by magnetic resonance imaging in healthy subjects during two different protocols. Vection was induced by an optokinetic drum, and subjects repeatedly rated the intensity of vection and nausea on 0–10 analog scales. Vection delayed gastric emptying {99% (89–102%) [median (interquartile ranges)] of volume retained at 28 min; control situation: 79% (69–81%), P < 0.05}. Antral contractile activity followed a distinct time course of rapid decrease [−64% (−72 to −59%) change from baseline activity] immediately after onset of drum rotation followed by gradual recovery upon withdrawal of the stimulus. No relationship was found between the severity of nausea and inhibition of gastric emptying or antral contractile activity. The inhibition of antral contractile activity appears to be a good measure of the peripheral response to vection but is probably independent of subjective symptom induction.

Retention of soluble99mTc-DTPA in the human lung: 24-h postdeposition

1997 ◽  
Vol 82 (4) ◽  
pp. 1378-1378 ◽  
Author(s):  
W. Michael Foster ◽  
Pamela T. Stetkiewicz ◽  
Arthur N. Freed
Keyword(s):  
Molecular Weight ◽  
Healthy Subjects ◽  
Human Lung ◽  
Lung Parenchyma ◽  
Respiratory Epithelium ◽  
Low Molecular Weight ◽  
Order Process ◽  
Epithelial Integrity ◽  
First Order ◽  
Lung Retention

Foster, W. Michael, Pamela T. Stetkiewicz, and Arthur N. Freed. Retention of soluble99mTc-DTPA in the human lung: 24-h postdeposition. J. Appl. Physiol.82(4): 1378–1382, 1997.—Clearance of low-molecular-weight solutes, e.g., radiolabeled chelate diethylenetriaminepentaacetate (DTPA), across epithelial surfaces of distal airways and the lung parenchyma is a broadly used technique to assess epithelial integrity. It has been generally assumed that clearance of solute follows a simple first-order process and that DTPA clearance through the respiratory epithelium and into blood and lymphatic channels is complete within a few hours. Using γ-camera imaging and a radiolabeled aerosol of99mTc-labeled DTPA, we observed in eight healthy subjects lung retention of radioisotope ∼24 h postdeposition of the 99mTc-DTPA. Residual lung retention at the 24-h end point averaged 6.0 ± 1.8 (SD)% of the amount of radioisotope initially deposited in the lung. This suggests that for normal healthy subjects a small amount of the99mTc radioisotope, either in a dissociated or chelated form, is nonpermeable or slowly cleared from respiratory tisssues.

scholarly journals Airway responsiveness depends on the diffusion rate of methacholine across the airway wall

2012 ◽  
Vol 112 (10) ◽  
pp. 1670-1677 ◽  
Author(s):  
Jason H. T. Bates ◽  
Chelsea A. Stevenson ◽  
Minara Aliyeva ◽  
Lennart K. A. Lundblad
Keyword(s):  
Smooth Muscle ◽  
Time Course ◽  
Airway Resistance ◽  
Diffusion Rate ◽  
Airway Responsiveness ◽  
Airway Wall ◽  
Methacholine Challenge ◽  
Airway Narrowing ◽  
Challenge Tests ◽  
Important Possibility

During methacholine challenge tests of airway responsiveness, it is invariably assumed that the administered dose of agonist is accurately reflected in the dose that eventually reaches the airway smooth muscle (ASM). However, agonist must traverse a variety of tissue obstacles to reach the ASM, during which the agonist is subjected to both enzymatic breakdown and removal by the bronchial and pulmonary circulations. This raises the possibility that a significant fraction of the deposited agonist may never actually make it to the ASM. To understand the nature of this effect, we measured the time course of changes in airway resistance elicited by various durations of methacholine aerosol in mice. We fit to these data a computational model of a dynamically contracting airway responding to agonist that diffuses through an airway compartment, thereby obtaining rate constants that reflect the diffusive barrier to methacholine. We found that these barriers can contribute significantly to the time course of airway narrowing, raising the important possibility that alterations in the diffusive barrier presented by the airway wall may play a role in pathologically altered airway responsiveness.

Preliminary Evaluation of a Weibull Function for Fitting Slow-Component Eye Velocity over the Time Course of Caloric-Induced Nystagmus

1989 ◽  
Vol 32 (3) ◽  
pp. 681-687 ◽  
Author(s):  
C. Formby ◽  
B. Albritton ◽  
I. M. Rivera
Keyword(s):  
Time Course ◽  
Slow Component ◽  
Weibull Function ◽  
Preliminary Evaluation ◽  
Mathematical Function ◽  
Before And After ◽  
Best Fitting ◽  
Eye Velocity ◽  
Fitting Parameters ◽  
Weibull Equation

We describe preliminary attempts to fit a mathematical function to the slow-component eye velocity (SCV) over the time course of caloric-induced nystagmus. Initially, we consider a Weibull equation with three parameters. These parameters are estimated by a least-squares procedure to fit digitized SCV data. We present examples of SCV data and fitted curves to show how adjustments in the parameters of the model affect the fitted curve. The best fitting parameters are presented for curves fit to 120 warm caloric responses. The fitting parameters and the efficacy of the fitted curves are compared before and after the SCV data were smoothed to reduce response variability. We also consider a more flexible four-parameter Weibull equation that, for 98% of the smoothed caloric responses, yields fits that describe the data more precisely than a line through the mean. Finally, we consider advantages and problems in fitting the Weibull function to caloric data.

scholarly journals A Novel Language Paradigm for Intraoperative Language Mapping: Feasibility and Evaluation

2021 ◽  
Vol 10 (4) ◽  
pp. 655
Author(s):  
Katharina Rosengarth ◽  
Delin Pai ◽  
Frank Dodoo-Schittko ◽  
Katharina Hense ◽  
Teele Tamm ◽  
...  
Keyword(s):  
Healthy Subjects ◽  
Intraoperative Complications ◽  
Evaluation Study ◽  
Awake Craniotomy ◽  
Language Mapping ◽  
Tumor Patients ◽  
Language Functions ◽  
Before And After ◽  
Assessment Time ◽  
Neuropsychological Outcomes

(1) Background—Mapping language using direct cortical stimulation (DCS) during an awake craniotomy is difficult without using more than one language paradigm that particularly follows the demand of DCS by not exceeding the assessment time of 4 s to prevent intraoperative complications. We designed an intraoperative language paradigm by combining classical picture naming and verb generation, which safely engaged highly relevant language functions. (2) Methods—An evaluation study investigated whether a single trial of the language task could be performed in less than 4 s in 30 healthy subjects and whether the suggested language paradigm sufficiently pictured the cortical language network using functional magnetic resonance imaging (fMRI) in 12 healthy subjects. In a feasibility study, 24 brain tumor patients conducted the language task during an awake craniotomy. The patients’ neuropsychological outcomes were monitored before and after surgery. (3) Results—The fMRI results in healthy subjects showed activations in a language-associated network around the (left) sylvian fissure. Single language trials could be performed within 4 s. Intraoperatively, all tumor patients showed DCS-induced language errors while conducting the novel language task. Postoperatively, mild neuropsychological impairments appeared compared to the presurgical assessment. (4) Conclusions—These data support the use of a novel language paradigm that safely monitors highly relevant language functions intraoperatively, which can consequently minimize negative postoperative neuropsychological outcomes.

scholarly journals Measuring phenotypic flexibility by transcriptome time‐course analyses during challenge tests before and after energy restriction

2019 ◽  
Vol 33 (9) ◽  
pp. 10280-10290 ◽  
Author(s):  
Inge P. G. Bussel ◽  
Parastoo Fazelzadeh ◽  
Gary S. Frost ◽  
Milena Rundle ◽  
Lydia A. Afman
Keyword(s):  
Time Course ◽  
Energy Restriction ◽  
Phenotypic Flexibility ◽  
Before And After ◽  
Challenge Tests

Changes In Prothrombin And Activated Partial Thromboplastin Time During Replacement Therapy With Human Recombinant Growth Hormone In Growth Hormone Deficient Adults

2020 ◽  
Vol 154 (Supplement_1) ◽  
pp. S102-S103
Author(s):  
Y S Kamel
Keyword(s):  
Growth Hormone ◽  
Replacement Therapy ◽  
Healthy Subjects ◽  
Recombinant Growth Hormone ◽  
Gh Replacement ◽  
Coagulation Tests ◽  
Before And After ◽  
Human Recombinant Growth Hormone ◽  
Male Patients ◽  
One Year

Abstract Introduction/Objective The aim of this study was to investigate the effects of GH administration on basic coagulation parameters: PT, aPTT and fibrinogen concentrations in adult GHD patients before and during one year of GH replacement. Methods Twenty-one adult patients with severe GHD (mean age +/- SE: 38.6 +/- 2.8 years) were included in this hospital based, prospective, interventional study. All patients were treated with rhGH for 12 months (GH dose: 0.4 mg/day for male and 0.6 mg/day for female patients). IGF-1 concentrations were determined using RIA-INEP kits. Basic coagulation tests, i.e. aPTT and fibrinogen concentrations, were measured before and after 3, 6 and 12 months of treatment with rhGH. Control values were obtained from fourteen “healthy” subjects matched by age, sex and body mass index (BMI). Results At baseline, we observed no significant differences in PT, aPTT and fibrinogen values between GHD and healthy subjects. IGF-1 concentrations increased significantly within 3 months of GH therapy (8.2 +/- 1.5 vs. 24.2 +/- 2.9 nmol/l, p &lt;0.05) and remained stable thereafter. A significant increase in PT values, which was more pronounced in female subjects, was noted after 6 and 12 months of treatment with GH. aPTT values increased significantly after 12 months of treatment only in male patients (28.8 +/- 4.6 vs. 39.7 +/- 2.1 s.; p &lt;0.05). No significant changes in fibrinogen concentrations were found during the study. Conclusion Twelve months of GH replacement therapy led to a significant increase in PT and aPTT values in adult GHD patients, while fibrinogen concentrations did not change. Changes in PT were more pronounced in female GHD patients, while an increase in aPTT values was observed only in male patients with GHD. The clinical significance of these changes needs further evaluation.

Effects of activation frequency and force on low-frequency fatigue in human skeletal muscle

1999 ◽  
Vol 86 (4) ◽  
pp. 1337-1346 ◽  
Author(s):  
Stuart A. Binder-Macleod ◽  
David W. Russ
Keyword(s):  
Healthy Subjects ◽  
Human Skeletal Muscle ◽  
Low Frequency ◽  
Variable Frequency ◽  
Activation Pattern ◽  
Constant Frequency ◽  
Mean Frequency ◽  
Before And After ◽  
Low Frequency Fatigue ◽  
Force Time

No comparison of the amount of low-frequency fatigue (LFF) produced by different activation frequencies exists, although frequencies ranging from 10 to 100 Hz have been used to induce LFF. The quadriceps femoris of 11 healthy subjects were tested in 5 separate sessions. In each session, the force-generating ability of the muscle was tested before and after fatigue and at 2, ∼13, and ∼38 min of recovery. Brief (6-pulse), constant-frequency trains of 9.1, 14.3, 33.3, and 100 Hz and a 6-pulse, variable-frequency train with a mean frequency of 14.3 Hz were delivered at 1 train/s to induce fatigue. Immediately postfatigue, there was a significant effect of fatiguing protocol frequency. Muscles exhibited greater LFF after stimulation with the 9.1-, 14.3-, and variable-frequency trains. These three trains also produced the greatest mean force-time integrals during the fatigue test. At 2, ∼13, and ∼38 min of recovery, however, the LFF produced was independent of the fatiguing protocol frequency. The findings are consistent with theories suggesting two independent mechanisms behind LFF and may help identify the optimal activation pattern when functional electrical stimulation is used.

Preoperative and postoperative cognitive functioning in patients with frontal meningiomas

2003 ◽  
Vol 98 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Oliver Tucha ◽  
Christian Smely ◽  
Michael Preier ◽  
Georg Becker ◽  
Geraldine M. Paul ◽  
...  
Keyword(s):  
Executive Functions ◽  
Cognitive Functioning ◽  
Time Course ◽  
Lesion Size ◽  
Test Battery ◽  
Surgical Removal ◽  
Specific Information ◽  
Content Type ◽  
Before And After ◽  
Fine Print

Object. There is presently no specific information available concerning the nature and course of cognitive deficits caused by intracranial meningiomas. In this prospective study the authors examined the cognitive functioning of patients with frontal meningiomas. Methods. Fifty-four patients with frontal meningiomas were examined neuropsychologically before and after neurosurgery. The test battery consisted of standardized instruments including those assessing memory, attention, visuoconstructive abilities, and executive functions. The time period between pre-and postoperative assessment ranged from 4 to 9 months. The patients' performance was compared with the results in 54 healthy adults who were also assessed twice by using the same test battery in a period ranging from 4 to 9 months. In addition, the effect on cognition of meningioma lateralization, localization, lesion size, edema, brain compression, time course, and the occurrence of preoperative seizures was analyzed. Conclusions. Except in the case of working memory, comparisons of pre- and postoperative assessments of cognition revealed no differences in memory, visuoconstructive abilities, or executive functions, although a postoperative improvement in attentional functions was observed. The results of this study indicate that the surgical removal of frontal meningiomas does not impair patients' cognitive functioning. Furthermore, improvements in attentional functions may occur in these patients.

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