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Biomedical subjects

Michael Vogel

Publications and source records attributed to Michael Vogel.

27 records · Page 2Linked to original sources
PubMed2004

[Drug monitoring of antipsychotics and antidepressants during acute admission in a psychiatric state hospital in Germany].

In the treatment of affective and schizophrenic psychosis, modern atypical antipsychotic agents and newer antidepressive agents recently have increasingly been used. In this prospective naturalistic study, patients were examined who had previously been treated psychopharmaceutically for a schizophrenic (n = 52) or depressive (n = 38) disorder and were readmitted in a psychiatric emergency clinic. While Serum levels were examined major interest was to find out similarities or differences in the drug compliance of schizophrenic and depressive patients before rehospitalization.

Acute Disease↗
PubMed2004

Developmental alterations in serotoninergic neurotransmission in Borna disease virus (BDV)-infected rats: a multidisciplinary analysis.

Neonatal Borna disease virus (BDV) infection of the rat brain serves as a valuable model for studying the pathogenesis of neurodevelopmental abnormalities following early brain injury. Previous experiments have demonstrated significant alterations in regional tissue content of serotonin (5-HT) in neonatally BDV-infected Lewis rats. The present study sought to provide more insights into postnatal virus-associated alterations in 5-HT neurotransmission by evaluating the density of 5-HT1a receptors in the hippocampus and 5-HT2a receptors in the cortex, regional 5-HT tissue concentrations, behavioral responses to a 5-HT agonist, quipazine, and numbers of neurons in specific subfields of the hippocampus on days 7, 14, and 30 after neonatal BDV infection in Lewis rats. Neonatal BDV infection was found to be associated with a gradual increase in the density of 5-HT2a and 5-HT1a postsynaptic receptors followed by an elevation of 5-HT contents at both the levels of synaptic terminals (i.e., cortex and hippocampus) and cell bodies (i.e., raphe nuclei). In addition, there was an enhanced behavioral response to quipazine. Virus-associated neurochemical and behavioral changes were accompanied by a decline in the number of neurons in the dentate gyrus and in the CA1 field of the hippocampus. No change in the number of neurons in the CA3/2 field of the hippocampus was observed. The present pattern of BDV-associated alterations in 5-HT brain system along with available data from other laboratories suggest that BDV might compromise axonal transport and/or release of 5-HT, resulting in decreased 5-HT neurotransmission.

Animals↗
PubMed2003

Noninvasive assessment of left ventricular force-frequency relationships using tissue Doppler-derived isovolumic acceleration: validation in an animal model.

BACKGROUND: We have demonstrated that myocardial acceleration during isovolumic contraction (IVA) is a sensitive index of right ventricular contractile function. In this study, we assessed the usefulness of IVA to measure left ventricular (LV) contractile function and force-frequency relationships in an experimental preparation. METHODS AND RESULTS: In study 1, we examined 6 pigs by use of tissue Doppler imaging of LV free wall and simultaneous measurements of intraventricular pressure, volume, maximal elastance (Emax), and dP/dtmax by conductance catheterization. Animals were paced via the right atrium at a rate of 130 bpm. IVA was compared with elastance during contractility modulation by esmolol and dobutamine and assessed during preload reduction and afterload increase. In study 2, in 6 more pigs, force-frequency data were obtained during incremental atrial pacing from 120 to 180 bpm. Study 1: Esmolol led to a decrease in IVA and Emax (P<0.03 and <0.02, respectively), both of which increased during dobutamine infusion (P<0.02 and <0.03, respectively). IVA was unaffected by significant (P<0.001) acute reduction of LV volume and a significantly increased LV afterload (systolic pressure increase, P<0.001). Study 2: There was a positive correlation between IVA and dP/dtmax (r2=0.92, P<0.05). As heart rate was increased from 120 to 160 bpm, there were significant increases in both IVA and dP/dtmax (P<0.0004 and P=0.02, respectively). Over the same range of heart rates, there was no significant change in Emax (P=0.22). CONCLUSIONS: IVA is a measurement of LV contractile function that is unaffected by preload and afterload changes within a physiological range and can be used noninvasively to measure LV force-frequency relationships.

Animals↗
PubMed2003

Doppler tissue echocardiography: can transesophageal echocardiography be used to acquire functional data?

BACKGROUND: To date there is no direct comparison of transesophageal and transthoracic Doppler tissue data in patients with cardiac malposition. We compared data acquired from both methods in an animal model. METHOD: We studied 10 15-kg Yorkshire pigs during incremental atrial pacing to modify myocardial responses. Peak isovolumic velocity (IVV) and isovolumic acceleration (IVA) during isovolumic contraction, ejection (S wave), and diastolic velocities (early passive and active filling, E and A wave, respectively) were measured. RESULTS: Bland-Altman plots showed comparable values for IVA, IVV, and E velocity using both methods. Measurements of A velocities were significantly different. S wave velocity measurements were significantly different in animals with cardiac malposition but not in those with levocardia. Malposition did not significantly effect measurements of IVA or IVV by either technique. CONCLUSION: Assessment of systolic function using the indices IVA and IVV by tranesophageal and transthoracic echocardiography are comparable. The tranesophageal assessment of velocities associated with greater degrees of myocardial shortening or lengthening cannot be directly compared with measurements derived from a transthoracic approach in patients with cardiac malposition.

Animals↗
PubMed2002

Validation of myocardial acceleration during isovolumic contraction as a novel noninvasive index of right ventricular contractility: comparison with ventricular pressure-volume relations in an animal model.

BACKGROUND: We have demonstrated that myocardial acceleration during isovolumic contraction (IVA) is a sensitive index of left ventricular contractile function. In this study, we assessed the utility of IVA to measure right ventricular (RV) contractile function. METHODS AND RESULTS: We examined 8 pigs by using tissue Doppler imaging of the RV free wall and simultaneous measurements of intraventricular pressure, volume, maximal elastance (e(max)), preload recruitable stroke work, and dP/dt(max) by conductance catheterization. Animals were paced in the right atrium at a rate of 130 beats per minute (bpm). IVA was compared with elastance during contractility modulation by esmolol and dobutamine and during preload reduction and afterload increase by transient balloon occlusion of the inferior vena cava and pulmonary artery, respectively. Data were also obtained during incremental atrial pacing from 110 to 210 bpm. Esmolol led to a decrease in IVA and dP/dt(max). During dobutamine infusion, IVA, dP/dt(max), preload recruitable stroke work, and e(max) all increased significantly. During preload reduction and afterload increase, IVA remained constant up to a reduction of RV volume by 54% and an RV systolic pressure increase of 58%. Pacing up to a rate of 190 bpm led to a stepwise increase in IVA and dP/dt(max), with a subsequent fall at a pacing rate of 210 bpm. CONCLUSIONS: IVA is a measurement of RV contractile function that is unaffected by preload and afterload changes in a physiological range and is able to measure the force-frequency relation. This novel index may be ideally suited to the assessment of acute changes of RV function in clinical studies.

Adrenergic beta-Agonists↗
PubMed2002

Diagnosis of sleep apnea by automatic analysis of nasal pressure and forced oscillation impedance.

Detecting and differentiating central and obstructive respiratory events is an important aspect of the diagnosis of sleep-related breathing disorders with respect to the choice of an appropriate treatment. The purpose of this study was to evaluate the performance of a new algorithm for automated detection and classification of apneas and hypopneas, compared with visual analysis of standard polysomnographic signals. The algorithm is based on time series analysis of nasal mask pressure and a forced oscillation signal related to mechanical respiratory input impedance, measured at a frequency of 20 Hz throughout the night. The method was applied to all-night measurements on 19 subjects. Two experts in sleep medicine independently scored the corresponding simultaneously recorded polysomnographic signals. Evaluating the agreement between two scorers by a weighted kappa statistic on a second-by-second basis, we found that inter-expert variability and the discrepancy between automatic analysis and visual analysis performed by an expert were not significantly different. Implementation of this algorithm in a device for home monitoring of breathing during sleep might aid in the differential diagnosis of sleep-related breathing disorders and/or as a means for follow-up and treatment control.

Airway Resistance↗
PubMed2002

Real-time three-dimensional fetal echocardiography--optimal imaging windows.

A total of 15 fetuses were scanned using 2-D array volumetric ultrasound (US). Acquired cardiac data were converted for rendering dynamic 3-D surface views and reformatting cross-sectional views. The image usefulness was compared between the data obtained from subcostal/subxiphoid and other imaging windows; the former are usually free of acoustic shadowing. Of 60 data sets recorded, 12 (20%) were acquired through subcostal windows in 6 (40%) patients. Subcostal windows were unavailable from the remaining patients due to unfavourable fetal positions. Of the 12 sets, 6 (50%) provided the dynamic 3-D and/or cross-sectional views of either the entire fetal heart or a great portion of it for sufficient assessments of its major structures and their spatial relationships. Of 48 data sets from other windows, only 9 (19%) provided such 3-D and/or cross-sectional views; the lower rate being due to acoustic shadowing. Real-time 3-D US is a convenient method for volumetric data acquisition. Through subcostal windows, useful information about the spatial relationships between major cardiac structures can be acquired. However, to offer detailed information, considerable improvement in imaging quality is needed.

Artifacts↗
PubMedDate not supplied

Incomplete forced expiration - estimating vital capacity by a mathematical method.

BACKGROUND: Vital capacity is a key parameter in the determination of lung function, usually assessed by means of a forced expiration maneuver. This maneuver can be exhausting, and patients often cannot complete it. OBJECTIVES: This study evaluates a method to estimate forced vital capacity (FVC) based on the extrapolation of volume-time curves from forced expiration. METHODS: The algorithm was applied to 2,363 volume-time curves from patients with and without respiratory disease. 416 of these spirograms originated from incomplete maneuvers. For each spirogram, estimated (FVC(est)) and measured FVC were compared with inspiratory vital capacity. RESULTS: Reliable FVC(est) were obtained for 82% of all and for 76% of the incomplete maneuvers. Regardless of the category of respiratory disease and acceptability of forced expiration, FVC(est) were close to inspiratory vital capacities. CONCLUSIONS: When assessing the lung function of patients who cannot complete forced expiration, this method could help to reduce the duration of maneuvers required to provide a reliable estimate for vital capacity.

Algorithms↗