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Biomedical subjects

A Doering

Publications and source records attributed to A Doering.

17 recordsLinked to original sources
PubMed2004

Overall alcohol intake, beer, wine, and systemic markers of inflammation in western Europe: results from three MONICA samples (Augsburg, Glasgow, Lille).

AIM: Anti-inflammatory effects of moderate alcohol consumption have been proposed to explain why moderate alcohol intake lowers coronary heart disease risk. We investigated the relationship between overall alcohol, beer or wine consumption and markers of systemic inflammation in three different geographical areas in Europe. METHODS AND RESULTS: Cross-sectional samples, each representative of the general population from Germany, Scotland, and France (MONICA Augsburg 1994/95, 2275 men and 2186 women, 25-74 years; Glasgow MONICA 1994/95, 561/616, 25-74 years, and MONICA Lille 1994/95, 581/574, 35-64 years) were studied. Alcohol intake was assessed by standardized interview. Adjusted means of C-reactive protein (CRP), fibrinogen, white blood cell (WBC) count, plasma viscosity (PV), and albumin were calculated among categories of alcohol intake, and separately for beer or wine consumption, by multiple linear regression. Self-reported moderate daily alcohol intake up to 40 g was associated with lower concentrations of CRP, fibrinogen, PV and WBC count, compared to non-drinking and heavy drinking, even after adjustment for various potential confounders. CONCLUSIONS: Moderate consumption of either wine or beer is associated with lower levels of systemic inflammatory markers in three different European areas, suggesting that ethanol itself might be largely responsible for the potential anti-inflammatory effects of these beverages.

Adult↗
PubMed2002

Do siblings of myocardial infarction patients have a specific management of hypertension?

The aim of this study was to determine whether the management of hypertension differs between siblings of myocardial infarction patients and the general population. Siblings aged 35 to 74 years, unaffected by myocardial infarction, were drawn from the Augsburg Family Heart Study, conducted in 1996-1997 in southern Germany (n = 524). The reference group consisted of participants of the third MONICA population-based survey conducted in 1994-1995 in the same area, who were aged 35 to 74 years and also unaffected by myocardial infarction (n = 3802). Prevalence, awareness, treatment and control of hypertension (defined by blood pressure > or = 140/90 mm Hg or use of antihypertensive medication) were compared between the two groups. The result was that the prevalence of hypertension was higher in the siblings (men: age-adjusted OR = 1.31, 95% CI: 0.99-1.75; women: age-adjusted OR = 1.83, 95% CI: 1.39-2.41). Male hypertensive siblings were more often aware and treated for hypertension than male hypertensives of the reference group whereas the level of awareness and treatment was comparable between female hypertensives of the two groups. In both genders, no difference in the degree of control was shown between hypertensives of the two groups. In conclusion the siblings and their physicians should pay more attention to the family history of myocardial infarction in order to improve the management of hypertension in this high risk group.

Adult↗
PubMed2001

Adenosine enhances neuroexcitability by inhibiting a slow postspike afterhyperpolarization in rabbit vagal afferent neurons.

BACKGROUND: Electrophysiological mechanisms by which adenosine may activate cardiac afferent neurons are unknown. Slow afterhyperpolarizations (AHPs) follow action potentials in a subset of vagal C afferents, rendering them inexcitable. The purpose of this study was to test the hypothesis that adenosine increases vagal neuronal excitability by blocking slow AHPs and to determine the adenosine receptor subtype mediating these effects. METHODS AND RESULTS: Using the perforated patch-clamp technique, we identified cultured adult rabbit nodose ganglion cells with slow AHPs in current-clamp mode. Trains of 100 current pulses at 20% above threshold were injected, with an interspike interval of 100 ms, and the number of action potentials triggered were counted and reported as the action potential response rate. During adenosine (10 micromol/L), slow AHPs were suppressed and action potential response rate was augmented from 3.8+/-0.5% at baseline to 28+/-7% after adenosine (P:=0.0009). The selective A(2)-adenosine receptor agonist NECA but not the A(1)-adenosine agonist CCPA replicated the adenosine effect. The selective A(2A)-adenosine antagonist ZM 241385 (10 nmol/L) but not the A(1) adenosine antagonist DPCPX (5 micromol/L) abolished the adenosine effect. We considered two alternative hypotheses: (1) A(2)-receptor-mediated suppression of I(Ca) leading to smaller increases in intracellular Ca during stimulation, resulting in less activation of I(K(Ca)) and consequent suppression of slow AHPs, or (2) A(2)-receptor-mediated elevation of cAMP directly suppressing slow AHPs. Under voltage-clamp conditions, adenosine did not significantly inhibit I(Ca), making the latter hypothesis more likely. CONCLUSIONS: Adenosine inhibits slow AHPs in vagal afferent neurons. This effect is most likely caused by A(2A)-receptor-mediated stimulation of cAMP production.

Action Potentials↗
PubMed2000

Localization of a small genomic region associated with elevated ACE.

Defining the relationship between multiple polymorphisms in a small genomic region and an underlying quantitative trait locus (QTL) represents a major challenge in human genetics. Pedigree analyses have shown that angiotensin I-converting enzyme (ACE) levels are influenced by a QTL located within or close to the ACE gene and most likely resides in the 3' region of this locus. We genotyped seven polymorphisms spanning 13 kb in the 3' end of ACE in 159 Afro-Caribbean subjects to evaluate the linkage disequilibrium between these sites and to narrow the genomic region associated with an elevated ACE level using a cladistic analysis. The linkage disequilibrium measurement D' and a haplotype tree revealed three distinct haplotype segments, presumably because of recombination. The value of the linkage disequilibrium parameter p(excess) was highest for site 22982, which is located in the middle segment. A series of nested, cladistic analyses confirmed that the other two regions are unlikely to be the ACE-linked QTL and that the variant resides in the middle region. Analyses of the same polymorphisms in 98 unrelated Europeans in the Monitoring Trends and Determinants in Cardiovascular Diseases (MONICA) study resulted in fewer haplotypes than were observed among the Afro-Caribbean subjects, suggesting that populations with greater genetic diversity may be especially informative for fine-scale mapping.

Black People↗
PubMed1999

Adaptable preprocessing units and neural classification for the segmentation of EEG signals.

In this contribution, a methodology for the simultaneous adaptation of preprocessing units (PPUs) for feature extraction and of neural classifiers that can be used for time series classification is presented. The approach is based upon an extension of the backpropagation algorithm for the correction of the preprocessing parameters. In comparison with purely neural systems, the reduced input dimensionality improves the generalization capability and reduces the numerical effort. In comparison with PPUs with fixed parameters, the success of the adaptation is less sensitive to the choice of the parameters. The efficiency of the developed method is demonstrated via the use of quadratic filters with adaptable transmission bands as preprocessing units for the segmentation of two different types of discontinuous EEG: discontinuous neonatal EEG (burst-interburst segmentation) and EEG in deep stages of sedation (burst-suppression segmentation).

Coma↗
PubMed1998

The associations of body size and body composition with left ventricular mass: impacts for indexation in adults.

OBJECTIVES: We investigated the relationship between body size, body composition and left ventricular mass (LVM) in adults, and assessed the impact of different indexations of LVM on its associations with gender, adiposity and blood pressure. BACKGROUND: The best way to normalize LVM for body size to appropriately distinguish physiologic adaptation from morbid heart morphology was discussed. METHODS: We undertook a community survey of 653 men and 718 women, aged 25 to 74 years. Lean body mass (LBM) was determined by bioelectric impedance analyses and LVM was assessed by two-dimensional guided M-mode echocardiography. RESULTS: After traditional indexations to body height, body height2.7, or body surface area, men had higher LVM than women (p < 0.001). These gender differences disappeared (p > 0.05) when LVM was indexed to LBM. The type of indexation also modified the strength of the association between adiposity and LVM. The estimated impact of body fat on LVM indexed to LBM was less than half that obtained with traditional indexations. In contrast, the magnitude of the associations of blood pressure with LVM was entirely independent of the type of indexation. CONCLUSIONS: This study showed the prominent influence of body composition on adult heart size. Indexation for LBM removed gender differences for LVM and reduced the impact of adiposity, but left the effects of blood pressure unchanged. We suggest that this approach be used for clinical and research applications.

Adaptation, Physiological↗
PubMed1997

Simultaneous spike detection and topographic classification in pediatric surface EEGs.

In this study, an algorithm is introduced for the automatic detection and simultaneous topographic classification of interictal regional spike activity in pediatric surface EEG records. The algorithm is based on the classification of the topographic distribution of instantaneous power by means of a 'group' trained classifier. The results of automatic spike analysis were compared with the decisions of two experienced electroencephalographers. Four routine EEG records exhibiting (multi)regional spikes were examined. The mean selectivity for the automatic spike detector was 84.6% (mean sensitivity 88.1%, mean specificity 89.3%) and for the electroencephalographers 85.3%. All spikes detected by the algorithm were simultaneously classified according to their topographic characteristics. The results of automatic spike classification (lateralization/localization) corresponded to the results of visual analysis.

Algorithms↗
PubMed1996

Use of adaptive Hilbert transformation for EEG segmentation and calculation of instantaneous respiration rate in neonates.

Broad, as well as narrow, band Hilbert transform filters (HTFs) were used as preprocessing units in the analysis of electroencephalogram (EEG) and respiratory movements in neonates. For these applications, new algorithms for the adaptation of the resonance frequency of a narrow-band-pass filter to the actual signal properties on the basis of an analytic filter design were developed. For the segmentation of the discontinuous EEG, the location of the resonance frequency was imbedded into the learning algorithm of a neural network (NN). In such automatic EEG pattern recognition, the detection of spike activity was taken into consideration. The spike detection scheme introduced uses broad-band HTFs as basis units. Additionally, the algorithm for the continuous control of the resonance frequency was applied to achieve the adaptation of the processing unit that performed the calculation of the instantaneous respiration rate, in this framework, a new on-line method for adaptive frequency estimation that is less sensitive to low signal-to-noise ratios (SNRs) was obtained. The new approaches introduced were tested in comparison with processing methods that have been established for the analysis of experimental and clinical data.

Algorithms↗
PubMed1995

Structure optimization of neural networks with A* -algorithm application in EEG pattern analysis.

The A* - Algorithm for heuristic search is applied to construct a Neural Network structure (NS) that optimally fits the structure of data to be learned. In this way, the user of Neural Networks (NN) is able to avoid the empirical testing of different structures. The method given here is applied to the recognition of different patterns derived from the EEG of an epileptic patient.

Algorithms↗
PubMed1995

Application of optimized pattern recognition units in EEG analysis: common optimization of preprocessing and weights of neural networks as well as structure optimization.

The main goal of this study is to demonstrate the possibility of training the Neural Network (multilayer perceptron) classifier and preprocessing units simultaneously, i.e., that properties of preprocessing are chosen automatically during the training phase. In the first realization step, adaptive recursive estimation of the power within a frequency band was used as a preprocessing unit. To improve the efficiency of special units, the power and momentary frequency estimation was replaced by methods that are based on adaptive Hilbert transformers. The strategy was developed to obtain optimized recognition units that can be efficiently integrated into strategies for monitoring the cerebral status of neonates. Therefore, applications (e.g., in neonatal EEG pattern recognition) will be shown. Additionally, a method of minimizing the error function was used, where this minimization is based on optimizing the network structure. The results of structure optimization in the field of EEG pattern recognition in epileptic patients can be demonstrated.

Algorithms↗
PubMed1993

Sodium/calcium exchanger in heart muscle: molecular biology, cellular function, and its special role in excitation-contraction coupling.

The Na/Ca exchanger has been examined with respect to its molecular biology, its cellular function, and its role in excitation-contraction coupling. The Na/Ca exchanger plays a central part in excitation-contraction coupling, setting the level of sarcoplasmic reticular calcium and contributing to the triggering of sarcoplasmic reticular calcium release. Functional biophysical studies with isolated single cells and caged calcium provide evidence that the Na/Ca exchanger works as a two step sequential transporter. In the heart there are about 250 exchangers.mu-2, operating at a turnover rate of up to about 2500.s-1, with the exchanger carrying -2.56 charges under normal conditions. The Na/Ca exchanger has been recently cloned from diverse mammalian species and several tissues and is largely conserved. It is clear, however, that the function of the Na/Ca exchanger is different in the different tissues. Thus work is in progress in several laboratories, including ours, to determine how the Na/Ca exchanger achieves its tissue specific function. Several modulatory motifs have been seen in studies of the exchanger that may explain some of the tissue specific differences. Interestingly the modulation of the Na/Ca exchanger (for example, by protons, sodium, calcium, ATP, calmodulin) seems to arise from interactions with the intracellular loop.

Animals↗
PubMed1992

Cross-sectional and longitudinal associations between high density lipoprotein cholesterol and women's employment.

This study examined the association between women's employment and high density lipoprotein (HDL) cholesterol. Subjects were 1.998 women aged 25-64 years who were sampled by the first MONICA Augsburg Survey (Monitoring of Trends and Determinants in Cardiovascular Disease). The women were sampled from the population of Augsburg, Federal Republic of Germany, in 1984-1985, were followed up for 3 years, and were reexamined in 1987-1988. In cross-sectional analysis (1984-1985), the mean HDL cholesterol level of employed women was 3.4 mg/dl higher than that of full-time homemakers (p less than 0.001). After adjustment for age, body mass, cigarette smoking, consumption of coffee and alcohol, use of sex hormones, leisure-time physical activity, and reproductive history, this difference decreased to 2.1 mg/dl and remained statistically significant (p less than 0.01). As was predicted from the cross-sectional findings, the mean HDL cholesterol levels of women who gave up employment and became full-time homemakers during the follow-up period decreased by 3.04 mg/dl (p less than 0.01), whereas homemakers who became employed showed no significant change in HDL cholesterol levels. The change in mean HDL cholesterol of employed women who had become homemakers could be explained in part by changes in alcohol consumption and in number of pregnancies. The authors conclude that giving up employment is related to life-style changes that are associated with a decrease in HDL cholesterol levels. Furthermore, the findings suggest that employment may exert a beneficial influence on coronary risk in women that is consistent with a positive association between employment and HDL cholesterol.

Adult↗
PubMed1991

Weight change and change of total cholesterol and high-density-lipoprotein cholesterol. Results of the MONICA Augsburg cohort study.

Data from the MONICA (Monitoring Trends and Determinants in Cardiovascular Disease) Augsburg cohort were used to study the effect of weight change on changes in serum levels of total and high-density-lipoprotein cholesterol. Weight gain was associated with rising levels of total cholesterol and falling levels of high-density-lipoprotein cholesterol in both sexes, more so in men than in women. Moreover, these relationships weakened with advancing age in women, but not in men. The results support the view that weight loss may more favorably affect lipid levels in men than in women, particularly at older ages.

Adult↗
PubMed1985

Oral contraceptive use and blood pressure in a German metropolitan population.

The relationship between blood pressure (BP) and oral contraceptive (OC) use in women has been examined with the data from the Munich Blood Pressure Study (MBS), a cross-sectional study with follow-up of a random sample of 3198 Munich citizens aged 30-69 (response rate 69.3%). Multiple linear and logistic regression analyses were run with BP as the dependent variable and age, OC use, obesity, alcohol consumption, and smoking habit as the independent variables. All second and third order interactions between the independent variables were tested during a backward stepping procedure. OC use appeared as a significant main effect in most of the analyses. The coefficient of the OC variable was about 3 in the linear regression analyses for both systolic BP and diastolic BP, indicating an increase of about 3 mmHg in the systolic and diastolic BP of the OC users. An analysis of the change in BP after one year in relation to change in OC user status has also been made. It was observed that women ceasing to use OC had a clear decrease in BP while those starting to use OC had on average an increase in BP.

Adult↗
PubMedDate not supplied

Alcohol consumption as a risk factor for high blood pressure. Munich Blood Pressure Study.

The Munich Blood Pressure Study (MBS), a 1980-81 cross-sectional study (with follow-up) of a random sample of 3198 Munich citizens aged 30-69 years (response rate 69%), revealed hypertensive blood pressure (BP) values in 17.7% of men and 10.7% of women (WHO criteria). One of the main goals of the MBS was to search for social, behavioral, and environmental risk factors for hypertension. The relationship between BP and five possible risk factors--alcohol consumption (g/day), cigarette smoking, oral contraceptive use, years of education, obesity (BMI)--has been examined. The major emphasis of this report is the relationship of alcohol consumption to BP. Multiple linear and logistic regression analyses were run controlling for both age and sex. All second- and third-order interactions between the independent variables were tested during a backward-stepping procedure. Alcohol consumption appeared as a significant main effect in many of the analyses. The coefficient of the alcohol variable ranged from 0.02 to 0.06 for men and women in the separate linear regression analyses for systolic and diastolic BP. Thus, for example, according to the model, the daily consumption of 1 liter of beer (40 g alcohol) may cause an increase in diastolic BP in women of 2.4 mm Hg.

Adult↗