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Biomedical subjects

A Witt

Publications and source records attributed to A Witt.

At least 37 records · Page 2Linked to original sources
PubMed1996

The application of methods of non-linear dynamics for the improved and predictive recognition of patients threatened by sudden cardiac death.

OBJECTIVES: This study introduces new methods of non-linear dynamics (NLD) and compares these with traditional methods of heart rate variability (HRV) and high resolution ECG (HRECG) analysis in order to improve the reliability of high risk stratification. METHODS: Simultaneous 30 min high resolution ECG's and long-term ECG's were recorded from 26 cardiac patients after myocardial infarction (MI). They were divided into two groups depending upon the electrical risk, a low risk group (group 2, n = 10) and a high risk group (group 3, n = 16). The control group consisted of 35 healthy persons (group 1). From these electrocardiograms we extracted standard measures in time and frequency domain as well as measures from the new non-linear methods of symbolic dynamics and renormalized entropy. RESULTS: Applying discriminant function techniques on HRV analysis the parameters of non-linear dynamics led to an acceptable differentiation between healthy persons and high risk patients of 96%. The time domain and frequency domain parameters were successful in less than 90%. The combination of parameters from all domains and a stepwise discriminant function separated these groups completely (100%). Use of this discriminant function classified three patients with apparently low (no) risk into the same cluster as high risk patients. The combination of the HRECG and HRV analysis showed the same individual clustering but increased the positive value of separation. CONCLUSIONS: The methods of NLD describe complex rhythm fluctuations and separate structures of non-linear behavior in the heart rate time series more successfully than classical methods of time and frequency domains. This leads to an improved discrimination between a normal (healthy persons) and an abnormal (high risk patients) type of heart beat generation. Some patients with an unknown risk exhibit similar patterns to high risk patients and this suggests a hidden high risk. The methods of symbolic dynamics and renormalized entropy were particularly useful measures for classifying the dynamics of HRV.

Death, Sudden, Cardiac↗
PubMed1995

Improved analysis of heart rate variability by methods of nonlinear dynamics.

The traditional analysis of heart rate variability (HRV) in the time and frequency domains seems to be an independent predictive marker for sudden cardiac death. Because the usual applied methods of HRV analysis describe only linear or strong periodic phenomena, the authors have developed new methods of HRV analysis based on nonlinear dynamics. In that way, parameters are extracted that quantify more complex processes and their complicated relationships. These methods are symbolic dynamics that describes the beat-to-beat dynamics and renormalized entropy that compares the complexity of power spectra on a normalized energy level. In an initial investigation, the HRV of 35 healthy subjects and 39 cardiac patients have been analyzed. Using discriminant functions, the authors found an optimal (100%) differentiation between the group of healthy subjects (even using only an age-matched subgroup of 12 subjects) and that of patients after myocardial infarction with a high electrical risk (Lown 4b). Applying this discriminant function to a group of patients with low electrical risk, four patients show the same behavior indicative of a high risk score, which might be a sign for a hidden high risk, two patients show healthy behavior, and the remaining patients show a separate pattern. The use of new methods of nonlinear dynamics in combination with parameters of the time and frequency domains in HRV offers possibilities for improved classification of HRV behavior. It is suggested that this could lead to a more detailed classification of individual high risk.

Adult↗
PubMed1995

Families who somatize.

This investigation extends a previous study of children of people with somatization disorder and children of less severely affected somatizers. We used the revised Diagnostic Interview for Children and Adolescents, revised, and abstracted medical records to compare families in which a child as well as a parent had unexplained somatic complaints; we also identified parental predictors of children's somatization. Children in families with somatizing children had more emergency room use, more suicidal behavior, and more disability. Children in families of somatization disorder adults had 11.7 times as many emergency room visits as less severely affected somatizers and missed 8.8 times as much school. Parental somatization, substance abuse, and antisocial symptoms predicted children's somatization. Physicians in primary care should be aware of the frequency with which somatization occurs in other members of a family when it is identified in one member.

Adolescent↗
PubMed1994

[New methods for the detection of high risk patients in cardiology].

Common non-invasive diagnostic methods like Holter monitoring or the analysis of high-resolution ECG and heart rate variability are unable to accurately assess the individual risk for sudden cardiac death, since they describe only statistical, linear or strictly periodic parameters. Using new methods of non-linear dynamics one can now calculate parameters which much better describe the dynamic behaviour of complex systems. The application of these new methods should therefore lead to an improved identification of high-risk patients. The results of this first pilot investigation show on the one hand that ventricular arrhythmias are quick detectable using phase space plots, and on the other hand that the new methods of non-linear dynamics could lead to a new classification of high-risk patients.

Adult↗
PubMed1993

Inhibitory effect of the TRFK-5 anti-IL-5 antibody in a guinea pig model of asthma.

To investigate the role of IL-5 in airway hyperreactivity and pulmonary eosinophilia, we used a model of allergic asthma in guinea pigs and a neutralizing monoclonal antibody (TRFK-5) directed against murine IL-5. Sensitized guinea pigs were challenged with 1% ovalbumin (OVA) aerosol and assessed for airway eosinophilia (by bronchoalveolar lavage [BAL] and histologic evaluation of airway tissue) and bronchoconstrictor responsiveness to substance P (SP) (as RL100 and Cdyn40) 24 h later. OVA challenge of sensitized animals caused a significant increase in airway responsiveness to SP, with a 4.9-fold decrease in RL100 and a 4.7-fold decrease in Cdyn40. Accompanying this increased sensitivity to SP was a 9-fold increase in eosinophils recovered in BAL and a 4- to 5-fold increase in eosinophils in intrapulmonary bronchial tissue. Intraperitoneal treatment with 10 mg/kg of the IL-5 antibody 2 h before OVA challenge blocked BAL and lung tissue increases in eosinophils but had no effect on the development of airway sensitivity to SP. In contrast, similar treatment with 30 mg/kg of this antibody blocked OVA-induced increased sensitivity to SP as well as BAL and lung tissue eosinophilia. These data suggest a critical and possibly independent role for IL-5 in allergic airway hyperresponsiveness and the accumulation of eosinophils within the lung of the guinea pig.

Animals↗
PubMed1990

Body part identification in 1- to 2-year-old children.

The purpose of this study was to examine the developmental sequence of body part identification in very young children, 11 to 25 months of age. In the first part of the study, 113 children, divided into five age groups (12-month-olds, 15-month-olds, 18-month-olds, 21-month-olds, and 24-month-olds), were asked to point to 20 body parts on a doll. The results indicated a positive correlation between number of parts correctly identified and increasing age. No sex differences or Sex X Age interactions were found. In the second part of the study, the difference between pointing to body parts on the self and pointing to body parts on a doll was examined in two groups of 2-year-olds. The results indicated no significant difference between the ability to point to body parts on a doll and the ability to point to body parts on the self. Factors that may contribute to the development of body part identification in 1- to 2-year-olds and the sequence in which body parts are learned are discussed. The results help provide diagnostic criteria for children with suspected delays in cognitive, language, or body scheme development.

Age Factors↗
PubMed1983

Prediction of discharges against medical advice from an alcohol and drug misuse treatment program.

A discriminant function method of data analysis revealed that statistically significant predictions could be made regarding AMA discharge, and that certain variables emerge consistently as predictors: a diagnosis involving personality disorder, admission after regular hours, age 20-29, intoxicated on admission, and less likely to have been referred by relatives or legal authorities.

Alcoholic Intoxication↗
PubMed1974

Bupivacaine carbonate and bupivacaine hydrochloride: a comparison of blood concentrations during epidural blockade for vaginal surgery.

Carbonated bupivacaine, plain bupivacaine hydrochloride, and bupivacaine hydrochloride with adrenaline were used to provide epidural analgesia for patients undergoing vaginal hysterectomy. Following injection to the blood concentrations of bupivacaine were measured at intervals over a period of 30 minutes. All three preparations produced satisfactory analgesia at a bupivacaine dose of 1.5 mg/kg body weight. The highest group mean blood concentrations were just outside the toxic dose range. Carbonated bupivacaine was absorbed most rapidly producing significantly higher blood concentrations up to 12 minutes after injection.

Age Factors↗