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Biomedical subjects

M Rother

Publications and source records attributed to M Rother.

At least 37 records · Page 2Linked to original sources
PubMed1990

EEG spectral analysis in newborns with and without severe brain damage at different conceptional ages. A preliminary report.

Spectral power (SP) analysis of neonatal discontinuous EEG pattern of bilateral Fp-T and T-0 derivations has been performed in 5 newborns with no or mild brain damage and in 5 newborns with severe brain damage matched for conceptional age (30-39, week). Discontinuous EEG was separated in interburst and burst intervals. SP of all frequency bands was depressed in newborns with severe brain damage, with the depression being more pronounced during interburst intervals. Surprisingly, a prominent depression of the SP of the derivations of the right hemisphere and of the delta frequency bands of severely handicapped newborns was found. Calculation of coherence between homologous bipolar derivations does not improve the possibilities to separate both groups.

Brain Damage, Chronic↗
PubMed1990

[EEG and evoked potential mapping].

By spectral EEG-mapping and EP-mapping, especially the topologic dimension of electrical brain activity can be evaluated for clinical use. On the other hand, this method allows the highest solution from all functional imaging procedures within the time dimension of brain activity. On the other hand, the ability of topological solution is limited. But the latter is probably better than hitherto assumed and surprisingly well at least regarding neonates. However, several methodological prerequisites described here must be fulfilled. From the pathophysiological point of view, the limits must be considered besides the diagnostic possibilities. Meanwhile, spectral EEG-mapping and EP-mapping are diagnostically used in all main fields of traditional EEG-analysis, like seizures and in the preadiagnostics of tumors a.o. Also in the diagnostics of cerebrovascular disease including transient ischemic attacks, the EEG-mapping and/or EP-mapping are useful within the total diagnostics. There is a similar situation in the diagnostics of degenerative brain disorders. But the significance of frequently described changes inpsychoses, partly also neuroses and other functional disorders is not clear. Altogether, this non-invasive, economically most favourable method for the functional imaging procedures in brain diagnostics is promising to extent the routine diagnostics also to a more precise manner.

Brain↗
PubMed1989

Better quantification of neonatal respiratory sinus arrhythmia--progress by modelling and model-related physiological examinations.

A large interindividual variability of parameters quantifying respiratory sinus arrhythmia were found in a well defined group of healthy neonates during constant conditions of examination. Reasons for this can be found by means of a mathematical model which is based on physiological data. The results indicate sharp inconsistencies in the transfer function between respiratory movements and resulting respiratory sinus arrhythmia and are dependent on a relative frequency unit fN (ratio of mean respiration rate to mean heart rate). The values of the coherence (as a function of this relative frequency unit) between respiratory movements and heart rate are also distinguished by a systematic decrease from lower to higher fN values (fN = 0.1-0.5) and inconsistencies in modelling as well as in physiological examinations. The reasons for both effects can be demonstrated. The study is the basis of a new qualitative step of quantification of respiratory sinus arrhythmia in neonates by power spectral and coherence analyses.

Arrhythmia, Sinus↗
PubMed1989

Cardiac aliasing--a possible cause for the misinterpretation of cardiorespirographic data in neonates.

Cardiac aliasing is a physiological phenomenon generating respiratory sinus arrhythmia in a frequency range lower than that of respiration if the mean respiration rate exceeds half of the mean heart rate. This was found in 8 out of 39 healthy fullterm newborns, 5 out of 33 fullterm and 3 out of 63 preterm newborns during intensive care. Quantification of cardiorespirographic data is considerably impaired in those cases when the mean respiration rate markedly exceeds half of the mean heart rate (two out of the 39 healthy full term newborns).

Arrhythmia, Sinus↗
PubMed1989

[Polygraphic studies of newborn infants at risk using acoustic stimulation close to and above the threshold level].

16 newborns were investigated by means of polygraphy (EEG, respirography, heart rate, psychogalvanic reflex and behavioural observations). They were acoustically stimulated (125, 750, 15000 and 3000 Hz, with stepwise increase of the intensity by 10 dBA) during the period of quiet sleep. Partial vegetative reactions appeared in 11 newborns between a stimulation intensity of 30 to 50 dBA. Changes of breathing were initially observed. A further increase of intensity caused reactions in heart rate, psychogalvanic reflex and also body movements. The EEG and behavioural states were never changed at this level of intensity. Reactions in these parameters were recurrently observable if stimulation intensity was higher than 80 dBA. Only half of all stimulations were followed by reactions. The results verify decreased threshold intensity to evoke partial vegetative reactions in newborns at risk and the same sequence of additional reactions in EEG and behavioural states as in healthy newborns following increasing stimulation intensity.

Acoustic Stimulation↗
PubMed1989

[Pilot study of the spectral analysis of the bifrontal EEG in healthy and newborn infants at risk].

The importance of neonatal bifrontal EEG recordings which were easily obtainable during intensive care was tested to improve the possibilities of computer-assisted analysis and to characterize cerebral cortical function of newborns-at-risk. The EEG was computerized by spectral analysis in 9 healthy term newborns and 6 term newborns-at-risk according to the age related patterns. Surprisingly, newborns-at-risk with good outcome show significant higher EEG spectral power than controls. But a secure monitoring is unpossible by bifrontal recordings alone. It was concluded that: 1. the bifrontal EEG recordings should be replaced by at least two interhemispheric recordings for neonatal cerebral monitoring, 2. the pattern-related analysis is necessary and 3. the discontinuous EEG is most suitable to characterize newborns-at-risk.

Brain Damage, Chronic↗
PubMed1988

Evidence of a previously undescribed form of respiratory sinus arrhythmia (RSA)--the physiological manifestation of "cardiac aliasing".

Within the fluctuations that occur in heart rate, there is a major component known as respiratory sinus arrhythmia (RSA), which up to now has been defined as heart rate variability which is synchronous with respiratory movements. We have now discovered that RSA synchronous to respiratory movements is only one example of RSA. If a special relationship exists between mean heart rate (fHR) and mean frequency of breathing (fB) such that fB greater than 1/2 fHR, RSA can be observed in a frequency range which is lower than the frequency of breathing. The mathematical fundamentals of this physiological phenomenon are the same as those for the "aliasing"-effect in signal sampling. Therefore, we have called this phenomenon "cardiac aliasing". We have been able to experimentally demonstrate this, up to now unknown, phenomenon in adult rabbits and dogs as well as in human neonates.

Animals↗
PubMed1988

Objective characterization and differentiation of sleep states in healthy newborns and newborns-at-risk by spectral analysis of heart rate and respiration rhythms.

Best parameters of power and coherence spectra of heart rate fluctuations (HR) and respiration rhythms (RR) were established to differentiate sleep states in healthy newborns and newborns-at-risk by means of multivariate variance and discriminant analysis. Nine healthy newborns and 20 newborns with low risk features were examined polygraphically. Long-term-variability of both HR and RR and coherence between HR and RR in the frequency range of 0.26-0.97 Hz, corresponding to Respiratory Sinus Arrhythmia, allow the best differentiation of neonatal sleep states S 1 and S2. Differentiation of healthy newborns and newborns-at-risk by these parameters was not possible. Thus, in studies dealing with low risk features in newborns sleep states must be previously classified. State 1 and 2 represent different autonomic organisations. State 1 is a neuro-vegetative, relatively stable state. State 2 shows cyclic increases of coherence between HR and RR within the frequency range of Respiratory Sinus Arrhythmia. These properties are related to autonomic brain stem functions and were absent in 6 out of the 20 newborns-at-risk.

Heart Rate↗
PubMed1987

Differentiation of healthy newborns and newborns-at-risk by spectral analysis of heart rate fluctuations and respiratory movements.

Neonatal heart rate and its interaction with respiration were computerized by spectral and coherence analysis (FFT) to differentiate healthy newborns (n = 9) from newborns with mild neonatal risk (n = 20). An increased mean heart rate and decreased total variability have been found in newborns-at-risk. Respiratory Sinus Arrhythmia is diminished in newborns-at-risk possibly caused by an impairment of autonomic brain stem function. Furthermore, Respiratory Sinus Arrhythmia holds a central position in differentiating healthy newborns and newborns-at-risk with and without neurological abnormalities during the first year of life. Respiratory Sinus Arrhythmia is diminished in newborns-at-risk showing these abnormalities. None of the parameters discriminates between the two groups of risk infants. The final prognostic value of our results must be confirmed in further clinical follow-up examinations.

Arrhythmia, Sinus↗
PubMed1979

Lymphocyte proliferation to phytohemagglutinin (PHA) in hepatitis B antigen-positive and -negative hepatitis.

Lymphocytes from patients with HBs-Ag-positive and -negative acute, chronic-persistent, and chronic-active hepatitis, from healthy controls and from patients with alcoholic liver cirrhosis were tested under standardized conditions. These included use of a single charge of Phytohemagglutinin (PHA-P) dissolved and diluted in one operation, of a single pool of homologous serum of the major blood group AB found free of HBs-Ag and cytotixic factor, and elaboration of PHA dose response curves in the presence of autologous and homologous serum in each case examined. During the early phase of acute virus hepatitis B and non-B, and in HBs-Ag-positive chronic persistent and active hepatitis, hyperresponsiveness of lymphocytes to PHA was observed independently of the source of the serum present in the culture. Lymphocyte responsiveness returned to normal in the later phase of acute hepatitis and depressed in alcoholic liver cirrhosis and in cases of HBs-Ag-positive chronic active hepatitis in which cirrhosis had developed. Although the cause of these alterations in lymphocyte responsiveness is not completely understood, the central role of a primary change of the lymphocytes themselves affecting their ability to react to PHA seems probable.

Acute Disease↗