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Biomedical subjects

E Schlenker

Publications and source records attributed to E Schlenker.

11 recordsLinked to original sources
PubMed2001

Cardiorespiratory and metabolic responses to injection of bicuculline into the hypothalamic paraventricular nucleus (PVN) of conscious rats.

Stimulation of the PVN increases mean arterial pressure (MAP) and heart rate (HR). However, little is known about its role in modulating ventilation. We tested the hypothesis that the stimulation of the PVN by microinjection of bicuculline methiodide (BMI), a gamma-aminobutyric acid (GABA)(A) receptor antagonist, increases ventilation in conscious rats. Oxygen consumption was also evaluated to determine if the ventilatory responses were associated with increases in metabolic rate. Male Sprague--Dawley rats were instrumented with femoral catheters to measure MAP and HR and cannulae were implanted 1 mm above the PVN. After 5 to 7 days of recovery, metabolic, ventilatory, and cardiovascular responses to artificial cerebrospinal fluid (aCSF) and BMI were evaluated. Rats were given a 50 nl unilateral microinjection of aCSF (the vehicle control) followed by 50 n1 of BMI (1 mM) into the other side. Microinjection of BMI significantly increased MAP compared to aCSF (145+/-4 vs. 124+/-5 mmHg, P<0.02), HR to 460+/-17 from 362+/-22 breaths/min (P<0.01). Ventilation increased by 300% (P=0.01) by stimulating frequency of breathing (176+/-14 compared to 79+/-12 breaths/min, P<0.005) and increasing tidal volume. Concomitantly, O(2) consumption doubled (P<0.006). These data suggest that in the PVN GABA receptors may be important regulators of cardiopulmonary and metabolic function in conscious rats.

Animals↗
PubMed1999

Gender-specific effects of CNQX administered into the arcuate nucleus on ventilatory patterns in rats.

This study evaluated the effect of microinjection of the non-N-methyl-D-aspartate (NMDA) receptor antagonist, cyano, 3-dihydro-7-nitrogluinoxaline-2, 3-dione (CNQX), into the arcuate nucleus of the hypothalamus on ventilation in male and female rats. Conscious rats received saline or 50, 100, or 200 pmol concentrations of CNQX on separate days. Significant interactions between dose and gender were observed on frequency, inspiratory (TI) and expiratory (TE) time, and tidal volume. CNQX depressed frequency, but increased tidal volume in female rats. Effects of CNQX in males on these ventilatory parameters were considerably less. In CNQX-treated females the decrease in frequency of breathing was primarily due to an increase in TI. Exposure of CNQX-treated female rats to hypercapnia, but not to hypoxia transiently decreased TI. No effect of CNQX was noted on oxygen consumption or body temperature. Thus, non-NMDA receptors in the arcuate nucleus are involved in modulating ventilatory patterns in a gender-specific manner independent of its effects on oxygen consumption or body temperature.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1998

Genome-wide search for asthma susceptibility loci in a founder population. The Collaborative Study on the Genetics of Asthma.

Founder populations offer many advantages for mapping genetic traits, particularly complex traits that are likely to be genetically heterogeneous. To identify genes that influence asthma and asthma-associated phenotypes, we conducted a genome-wide screen in the Hutterites, a religious isolate of European ancestry. A primary sample of 361 individuals and a replication sample of 292 individuals were evaluated for asthma phenotypes according to a standardized protocol. A genome-wide screen has been completed using 292 autosomal and three X-Y pseudoautosomal markers. Using the semi-parametric likelihood ratio chi2 test and the transmission-disequilibrium test, we identified 12 markers in 10 regions that showed possible linkage to asthma or an associated phenotype (likelihood ratio P < 0.01). Markers in four regions (5q23-31, 12q15-24.1, 19q13 and 21q21) showed possible linkage in both the primary and replication samples and have also shown linkage to asthma phenotypes in other samples; two adjacent markers in one additional region (3p24.2-22) showing possible linkage is reported for the first time in the Hutterites. The results suggest that even in founder populations with a relatively small number of independent genomes, susceptibility alleles at many loci may influence asthma phenotypes and that these susceptibility alleles are likely to be common polymorphisms in the population.

Adolescent↗
PubMed1997

[Effect of noninvasive ventilation on pulmonary artery pressure in patients with severe kyphoscoliosis].

BACKGROUND: Many studies have shown, that non invasive ventilation via nasal access can normalize alveolar ventilation for individuals due to kyphoscoliotic deformity. The purpose of this study was to evaluate the effect of nasal IPPV on the pulmonary artery pressures (Pam) and the sleep efficiency of kyphoscoliotic individuals. PATIENTS AND METHODS: Five patients were studied (4 men, 1 woman; age 50.5 +/- 6.9 years): all patients showed hypoxemia and hypercapnia before therapy. We followed the patients about 6 months under NIPPV. We measured PImax, PaO2, PaCO2, Pam before and after 6 months with NIPPV. RESULTS: PImax increased from 4.9 +/- 2.3 kPa to 6.5 +/- 1.3 kPa, PaO2 increased from 46.2 +/- 12.2 mmHg to 56.7 +/- 8.5 mmHg. PaCO2 decreased from 53.0 +/- 3.2 to 45.3 +/- 3.2. Pam decreased from 41.0 +/- 15.1 to 23.2 +/- 10.7 in 6 months of NIPPV. Total sleep time increased from 222 +/- 52 min to 326 +/- 43 min with NIPPV. CONCLUSION: Similar to O2 long-term therapy in patients with COPD. NIPPV delivers in patients with kyphoscoliotic deformity a significant reduction of pulmonary artery pressure and increase of sleep quality.

Adult↗
PubMed1997

Upper airway resistance syndrome.

Obstruction of the upper airway may cause arousals resulting in daytime sleepiness and cardiovascular disturbances. The upper airway resistance syndrome may easily be overlooked because conventional measurements of oronasal airflow and thoracic and abdominal efforts are not sensitive enough. By measuring esophageal pressure even small disturbances can be detected, but the esophageal gauge may disturb sleep. We conclude that other, less invasive methods like measurements of impedance by forced oscillation technique, or flattening of the inspiratory flow contour could be valid alternatives in the diagnosis of the upper airway resistance syndrome. Other methods, such as measurements of the pulse transit time, phase angle, or systolic blood pressure profile are promising, but need further evaluation.

Airway Obstruction↗
PubMed1997

[Computer-assisted nCPAP settings in comparison with conventional methods].

CPAP with constant pressure is the method of choice to treat obstructive sleep apnoea. To find the optimal pressure, automatic systems were developed, permitting computerised titration of pressure based on respiratory patterns. One important point in the algorithm of titrating pressure is the shape of the inspiratory breath flow-time relation. It can be used to detect early inspiratory obstruction. In the present study the results of automatic CPAP titration were compared with conventional constant CPAP. In 12 patients with obstructive sleep apnoea syndrome two polysomnographies were performed after diagnosis and conventional titration. In a randomised cross-over study the adequate constant CPAP was compared with computerised variation of pressure by Autoset-CPAP. During both methods apnoeas, hypopnoeas and snoring were reduced. In the autoset mode the number of apnoeas and hypopnoeas was 30.14 +/- 17.6/sleeping time, in the constant mode it was 7.9 +/- 11.2/sleeping time (p < 0.01). The number of episodes with snoring in the autoset mode was 18.7 +/- 21.8 and in the constant pressure mode 7.9 +/- 11.2 (p = 0.054). No difference could be detected in respect of sleeping time, sleep efficiency, arousals and sleep stages. We conclude that in patients accepting constant high pressures constant CPAP remains the method of choice. Automated CPAP offers an alternative in the case of pressure intolerance beneath BiLevel-CPAP.

Algorithms↗
PubMed1997

[Comparative study of thoracic and abdominal effort, respiratory oscillatory impedance (ROI) and intrathoracic pressure in sleep apnea syndrome].

Oesophageal pressure (Pes) and oronasal flow are necessary to describe upper airway obstruction in patients with obstructive sleep apnoea syndrome (OSAS), but Pes interferes with sleep. We developed a device applying an oscillating flow (20 Hz) through a nasal mask. An additional flow (2.6 l/min) is needed to reduce dead space and humidity. 24 patients (age 55.8 +/- 8.3 years, BMI 28.6 +/- 3.9, RDI 38.6 +/- 19.4, Raw 0.27 +/- 0.07 kPa/s/l) underwent polygraphy (oronasal flow, thoracic and abdominal effort, oxygen saturation, microphone, heart rate). Pes and oscillatory impedance (OI) were measured simultaneously. During snoring, hypopnoeas and apnoeas we compared Pes, OI and effort values for the detection of number and period of airway obstruction. The average Pes during habitual snoring was -3.2 +/- 0.8, during hypopnoeas -3.9 +/- 1.1 and during apnoeas -4.4 +/- 1.6 kPa. We found no significant difference in respect of the number and period of obstruction in patients with apnoeas, whereas in patients with incomplete obstruction (hypopnoea) Pes and OI were found to be more sensitive in detecting obstruction than effort (period: 27.0 +/- 9.1 sec (Pes), 29.0 +/- 4.8 sec (OI) vs. 20.0 +/- 6.8 sec (effort); number: 34.0 +/- 9.1 (Pes), 35.0 +/- 8.5 (OI) vs. 23.0 +/- 9.5 (effort). There is a significant correlation between Pes and OI (r = 0.89). OI is shown to be equally sensitive in identifying Upper Airway Resistance Syndrome as compared to Pes. This method is more convenient than conventional measurements such as Pes and it could be an alternative.

Adult↗
PubMed1996

[Significance of oscillatory impedance in etiological determination of arousal in sleep related respiratory disorders].

Conventional registration of cardiorespiratory data may not explain daytime sleepiness in some patients. Polysomnography may detect arousal reactions that can only be explained by additional registration of esophageal pressure. We developed a device (oscillatory impedance [OI]) which applies an oscillating flow via a nasal mask that allows to detect the pathophysiologic findings of upper airway resistance syndrome. 25 patients (age 47.3 +/- 5.6 years, body mass index 26.6 +/- 3.8 kg/m2) underwent conventional polysomnography and additional measurement of OI. In 59% arousal reactions could not be explained by respiratory data whereas OI demonstrated intermittend obstruction of extrathoracic airways. We therefore conclude that patients with daytime sleepiness that cannot be explained by conventional polysomnographic registrations should undergo measurement of OI.

Adult↗
PubMed1996

[Effect of automatically titrated CPAP systems on sleep and respiration in sleep apnea syndrome].

UNLABELLED: We compared an automated self setting CPAP-titration with conventional constant CPAP. In 12 patients with obstructive sleep apnea syndrome 2 polysomnographies were performed after introduction of CPAP-therapy. In a randomized cross-over study a constant CPAP during one night and in a second night a computerized variation of pressure was applied by a self-setting CPAP-device (Auto AdjustTM CPAP). During both methods apneas, hypopneas and snoring were reduced. Apnea index was reduced from 32.5 +/- 28.5 at diagnosis to 3.3 +/- 4.7 by Auto Adjust CPAP and to 4.0 +/- 5.3 by constant CPAP. The results of the 2 methods were not significantly different. Total sleep-time, sleep efficiency and sleep stages did not show any significant difference. CONCLUSIONS: In case of pressure-intolerance automated self setting CPAP offers an alternative beneath BiPAP. The significance of this method with regard to BiPAP therapy must further be evaluated.

Airway Resistance↗
PubMed1992

Low level mosaicism for a balanced 7;14 translocation in the father of an abnormal 7q+ child.

A child with a 7q+ chromosome abnormality had a father with 0.5% mosaicism for a balanced 7;14 translocation. This mosaicism was not found in 100 fibroblasts. This degree of mosaicism is well below the limits usually detected by standard clinical cytogenetic protocols. However, the one abnormal cell cannot be disregarded in this case, since it can serve as an explanation of the child's genotype. This case serves to illustrate the need for detecting subtle degrees of mosaicism for structural anomalies in humans and brings to question the true population frequencies of mosaic balanced translocation carriers.

Chromosome Aberrations↗