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Biomedical subjects

F Heydenreich

Publications and source records attributed to F Heydenreich.

At least 19 recordsLinked to original sources
PubMed2006

[Digital patient record for remote monitoring of intraocular pressure, blood pressure and serum glucose].

BACKGROUND: At the University Eye Hospital of Greifswald, we have developed a digital patient record that allows close monitoring of glaucoma, diabetes and hypertension. The record stores contemporary, long-term profiles containing intraday variation and interaction of intraocular pressure, blood pressure and serum glucose levels even at night. METHODS: All patients are equipped with a home monitoring system. They subsequently transmit self-measurements via the "telemedical interface" to the server. Physicians use a web front-end to access electronic patient records; this provides a PDF export filter for printing. We intend to include a total number of 120 patients from Mecklenburg-Vorpommern who suffer from glaucoma possibly combined with hypertension/diabetes. This long-term investigation was designed as a randomised cross-over study in two groups. RESULTS: Especially for this project an electronic patient record was developed and implemented. The components of the home monitoring system were modified and connected to a custom-built "telemedical interface". To date the study includes 120 patients, 60 of whom constantly measure and transmit their values to the electronic patient record, while the others are treated without home monitoring. All self-measurements are presented in a tabular form. In addition, dynamically generated graphics provide a diagrammatic view of all values. On demand, a detailed protocol for every single measurement report allows a comprehensive evaluation of the quality of the self-measurements. Ocular perfusion pressure is calculated automatically from intraocular pressure and blood pressure. The presented system documents continuously all information that is relevant for treatment and provides fast access for all attending physicians. CONCLUSIONS: Central data collection and unlocalised access improve information exchange between involved physicians. Flexible measurement periods allow the detection of pressure spikes even at night. In addition, this may help to classify glaucoma (normal-pressure glaucoma) and its causal connection to blood pressure. The patients benefit from individualised therapy adaptation and early therapeutic intervention in case of critical parameters.

Blood Glucose Self-Monitoring↗
PubMed1992

Enhancement of nerve fibre regeneration by nucleotides after peripheral nerve crush damage. Electrophysiologic and morphometric investigations.

The effect of nucleotide administration on the regeneration of myelinated nerve fibres following crush injury to the sciatic nerve of the rat was studied using both morphometric and electroneurophysiologic techniques. After a standardized localized crush lesion of the right sciatic nerve, rats were given nucleotides daily at a dosage of 3.0 mg/kg body wt uridine monophosphate (UMP), 2.5 mg/kg body wt cytidine monophosphate (CMP) or 3.0 plus 2.5 mg/kg body wt UMP plus CMP, respectively. Observations were made after 20, 40 and 60 days of nerve regeneration for comparison with age-matched crushed or nonoperated controls. Electroneurophysiologic studies of right sural nerves were performed as single fibre measurements. Morphometry was performed on semithin transverse sections of the right common peroneal nerve with a fully automatic interactive image analysis system. Forty days after crush injury the single fibre conduction velocity of all type II afferents in the UMP/CMP treated group was significantly accelerated. There was a trend (10% greater than or equal to p greater than or equal to 5%) to increase of mean efferent single nerve fibre function at this time. Morphometry of nerve fibres revealed a trend to enlargement of mean fibre area and mean fibre diameter related to increased myelin area and myelin thickness. After 60 days, there was a trend to increase of single fibre conduction velocity of all type II afferents in the UMP/CMP treated group. Automated morphometry revealed a significant increase for the following parameters: fibre area, fibre diameter, myelin area, myelin thickness and axon area.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Acceleration of nerve and muscle regeneration by administration of nucleotides--electroneurophysiological and morphometrical investigations.

The effect of nucleotide administration on the regeneration of myelinated nerve fibres following crush injury to the sciatic nerve of the rat was studied using morphometric techniques. In addition morphometrical investigations of peroneal and soleal muscles were performed at different times. After a localized crush lesion of the right sciatic nerve, rats were given nucleotides daily at a dosage of 3.0 mg/kg body wt uridine monophosphate (UM), 2.5 mg/kg body wt cytidine monophosphate (CMP) or 3.0 plus 2.5 mg/kg body wt UMP plus CMP, respectively. Observations were made after 20, 40 and 60 days of common peroneal nerve regeneration for comparison with age-matched crushed or nonoperated controls. Forty days after daily UMP/CMP administration the single fibre conduction velocity of all type II afferents was significantly accelerated. There was a trend towards increased mean fibre area related to increased myelin area. Mean diameter of type II muscle fibres was increased. After 60 days, there was a trend to increase of single afferent fibre conduction velocity in the UMP/CMP group. In the same group automated morphometry revealed a significant increase of nerve fibre area, myelin area and axon area. At this time an increase was found of type I and/or type II muscle fibres in all animal groups. The present results suggest that both axons (neurons) and myelin sheaths (Schwann cells) of regenerating nerve fibres and regenerating muscle fibres are influenced by nucleotide administration.

Animals↗
PubMed1991

Age-related changes of heart rate power spectra in a diabetic man during orthostasis.

We used spectral analysis of heart rate variability during orthostatic load in diabetic patients in order to provide quantitative information about first, the alterations of vagal and beta-adrenergic nervous system influence on the heart and secondly, the relation of spectral components of heart rate variability to age. The respiration-related power, and indirect estimate of vagal cardiac control, was significantly reduced in diabetics as compared with controls in both the supine (diabetics: 0.39 (0.18-1.15) l/min2 [median and 25-75% percentiles], controls: 1.52 (0.54-3.84) l/min2, 2P less than 0.01) and the standing (diabetics: 0.27 (0.12-0.84) l/min2, controls: 2.22 (0.67-5.14) l/min2, 2P less than 0.0001) body posture. The difference between supine and standing values of mid-frequency power (delta MF power) that represents beta-adrenergically mediated heart rate variability was significantly smaller in diabetics (delta MF: 0.79 (0.18-3.84) l/min2) than in controls (delta MF: 8.07 (4.35-17.99) l/min2) (2P less than 0.0001). Power of almost all frequency components declined exponentially with age in both positions and groups studied. The decline in power of heart rate variability was more pronounced in controls than in diabetics for either posture. An age-associated significant decrease in delta MF was found in controls (Y = 33.16-0.60X, P less than 0.05, r = -0.49) as compared to diabetics (Y = 8.70-0.16X, P greater than 0.05, r = -0.24). Our results suggest a decreased vagal and sympathetic nervous system input into the heart in diabetics. The premature loosened coupling between heart rate spectral power and age suggests that diabetes mellitus accelerates the aging process. Computerized spectral analysis of heart rate variability seems to be a very sensitive tool to evaluate the influence of the autonomic nervous system on the heart.

Adult↗
PubMed1991

[Acceleration of muscle regeneration by nucleotide administration. Experimental morphometric studies].

Morphometric studies of the peroneus longus muscle as well as of the soleus muscle were performed 20, 40 and 60 days after crush injury of sciatic nerve and continuous administration of nucleotides. 96 female Wistar rats were used in the experiments. Under ether anesthesia a crush injury was performed on the right sciatic nerve. 53 rats were injected daily with nucleotides (uridine monophosphate [UMP], cytidine monophosphate [CMP] or UMP plus CMP [UMP/CMP], respectively), and 43 control animals were given injections of saline. Morphometric studies of right peroneus longus and soleus muscles were performed with the aid of a semiautomatic technique to measure muscle fibre diameters. After 20 days there were no differences between mean muscle fibre diameters. 40 days after the beginning of the experiments semiautomated morphometry revealed an increase of type II fibre diameters in the UMP/CMP group. There were enlargements of type II fibres in the UMP and the CMP group after 60 days. At the same time larger diameters of type I fibres were found in the UMP/CMP group (trend) and in the UMP group. In conclusion the results presented here indicate, that the administration of nucleotides possibly represents a new opportunity for the treatment of traumatic nerve and muscle lesions.

Animals↗
PubMed1990

Heart rate variability in diabetic patients during orthostatic load--a spectral analytic approach.

Spectral analysis of heart rate variability (HRV) was used to assess the autonomic nervous control of cardiac function during orthostatic load in insulin-dependent diabetic patients and healthy subjects. The diabetic patients were divided into three groups: diabetics without neuropathy (group 1), diabetics with peripheral neuropathy (group 2), and diabetics with peripheral and autonomic neuropathy (group 3). Resting mid-frequency (MF, 0.05-0.15 Hz) and respiration-related (RF, power around respiration rate) HRV were significantly lower in group 2 and 3 diabetics than in controls, indicating a reduced parasympathetic nervous system influence on the heart. Standing MF and RF spectral power data were significantly lower in all diabetic groups than in controls, suggesting marked alterations in the autonomic cardiovascular control during a mild physical load not only in symptomatic diabetics but also in patients with no signs and symptoms of neuropathy. The difference between supine and standing MF power, an estimate of beta-adrenergic influence on the heart, was significantly lower in all diabetic subject groups studied than in controls. This suggests a reduced sympathetic nervous system influence on the heart in diabetic patients. Our data suggest that computerized spectral analysis of HRV during orthostatic load seems to be a very sensitive method of evaluating of the autonomic nervous systems influence on the heart in patients suffering from diabetes mellitus.

Adult↗
PubMed1990

A non-invasive approach to cardiac autonomic neuropathy in patients with diabetes mellitus.

The purpose of this study was to obtain information regarding the participation of the sympathetic nervous system in cardiac autonomic neuropathy in patients suffering from diabetes mellitus employing spectral analysis of heart rate variability in the supine and standing posture. Ten insulin-dependent diabetic patients (29 +/- 2 years) with a short to moderately long duration of diabetes (11 +/- 1 years) and cardiac vagal neuropathy based on measurements of respiratory sinus arrhythmia were compared to 10 healthy volunteers (27 +/- 1 years) before and after the administration of atropine and atropine plus propranolol. In diabetic patients the reactivity in total power (delta TP) from supine to upright position was significantly lower compared to control subjects before and after atropine. There was no significant difference in delta TP between diabetics and controls after atropine plus propranolol. The magnitude of TP increase is essentially due to the increase of blood pressure related heart rate fluctuations (delta MF) from lying to standing and dependent on beta-adrenergical efferent activity to the heart. In diabetic patients as well as in normal subjects under the influence of atropine plus propranolol the delta MF power was significantly lower compared to the unmedicated control and atropine group. There was no significant difference between diabetics and controls after combined autonomic blockade. It was concluded that delta MF heart rate spectral power could serve as an indirect, non-invasive, quantitative and sensitive marker of early cardiac sympathetic damage.

Adult↗
PubMed1990

[The nosological situation of hereditary motor and sensory neuropathies (HMSN, Charcot-Marie-Tooth disease, neural muscular atrophy)].

Hereditary motor and sensory neuropathies (HMSN) comprise a heterogeneous group of disorders. Since phenotypic manifestations are similar in most families, classification is based on differences in the mode of inheritance, onset and progression of the disease, nerve conduction velocity and nerve biopsy findings. Autosomal dominant, autosomal recessive, X-dominant and X-recessive forms, substantial intrafamilial differences, intermediate forms and the combination of neuropathies with spinocerebellar degeneration within one and the same sibship have been described. On the basis of selected own cases it is demonstrated that there is a broad spectrum of functional and structural abnormalities depending on the progression of the disease and on the site of nerve studied (proximal or distal part). Both the neuronal and hypertrophic variants begin with axonal degeneration of the dying back type followed by segmental demyelination and variable degrees of hypertrophic Schwann cell proliferation. Constantly, posterior columns of the spinal cord reveal fiber loss. Since the molecular basis of the different forms remains to be clarified it seems to be of greater interest to underline common features than to separate seemingly different nosological entities. It is suggested that the latter are partly the result of a selection of cases with a variable severity. Evidently, the syndrome of myatrophic ataxia comprises apart from "pure" HMSN with unsignificant degenerations of posterior columns and "pure" Friedreich's ataxia with mild peripheral nerve fiber loss intermediate forms.

Adult↗
PubMed1990

[Automatic microscopic image analysis of semithin sections of peripheral nerves using the program Image-C/Nerve-Neuropathy].

Visiomanual morphometric analysis of peripheral nerve fibres has proved to be error-laden and inadequate. An automatic interactive programme was, therefore, developed for microscopic image analysis and feature extraction. Contours of myelin sheaths were properly identifiable, but an interactive programme component was found to be required to measure the remainder of two to 5% of fibres. Image analysis is shown to generate descriptive statistical features.

Humans↗
PubMed1989

Effect of low-dose atropine on heart rate fluctuations during orthostatic load: a spectral analysis.

Spectral analysis was utilized in order to determine the influence of low (0.7 microgram/kg)-dose atropine sulfate injections on the isolated spectral power components of heart rate fluctuations in contrast to moderate (0.02 mg/dose)-dose atropine and unmedicated states in human subjects during orthostatic load. Low-dose atropine decreased mean heart rate and increased respiration-related spectral power compared with controls in both the supine and standing posture. In supine subjects total power (0.01-0.5 Hz) was unchanged compared with controls due to a decreasing trend of low-frequency (0.01-0.05 Hz) and mid-frequency (0.05-0.15 Hz) heart rate spectral power. Standing upright, there was a distinct increase in total power with significantly higher values than in the controls resulting from an enormous activation of mid-frequency heart rate fluctuations. The peak frequency of the mid-frequency component was increased with a strong tendency compared with controls. Moderate-dose atropine increased mean heart rate and decreased total power, mid-frequency and respiration-related heart rate spectral power and peak frequency compared with controls in both positions. Our results suggest that low-dose atropine affects the interaction between sympathetic and parasympathetic limbs in the autonomic control of cardiac function in a complex manner producing a differentiated pattern of heart rate fluctuations dependent on the body posture. We suggest that low-dose atropine augments and moderate-dose atropine attenuates the vagal cardiac efferent activity in each position.

Adult↗
PubMed1989

Effects of modified respiratory rhythm on heart rate variability during active orthostatic load.

The experiments were carried out to study the influence (a) of 3 different respiratory frequencies (0.12, 0.20 and 0.35 Hz) on heart rate power spectra during orthostatic load with special reference to the peak frequency of mid-frequency heart rate fluctuations, and (b) of variation in respiratory depth on this peak frequency in supine position. The peak frequency of mid-frequency heart rate fluctuations was shifted to lower frequency values in response to orthostasis despite the constant respiratory frequency for either posture. No differences in peak frequency were observed between respiratory frequencies of 0.20 and 0.35 Hz in both supine and standing position and between the two extreme patterns of respiratory depth. We suggest that the shift of the peak frequency of mid-frequency heart rate fluctuations to the lower end of the heart rate power spectrum during orthostasis represents an original effect independent of depth and frequency of respiration.

Adult↗
PubMed1987

Contributions of sympathetic and vagal mechanisms to the genesis of heart rate fluctuations during orthostatic load: a spectral analysis.

Spectral analysis was utilized in order to determine the influence of postural change on heart rate fluctuations and respiratory frequencies and to evaluate the frequency-specific contributions of both vagal and beta-adrenergic mechanisms to the genesis of the heart rate fluctuations during change in posture. In unmedicated subjects the total power (0.01-0.5 Hz) of heart rate fluctuations and the relative power at the mid-frequency band (0.05-0.15 Hz) were significantly increased in response to postural change, while the relative power of high-frequency fluctuations (0.15-0.5 Hz) was significantly depressed. Low-frequency fluctuations (0.01-0.05 Hz) were unchanged. The respiratory frequency was non-significantly slowed. The coherence between heart rate and respiration showed a significant reduction during orthostatic load. The heart rate fluctuations above 0.05 Hz were abolished by vagal blockade, during supine rest, while beta-adrenergic blockade reduced fluctuations at the mid-frequency band. Combined blockade caused a depression of heart rate fluctuations over the entire frequency range. On standing, vagal blockade or autonomic double blockade caused a decrease in heart rate fluctuations at each frequency band. After beta-adrenergic blockade alone, mid-frequency and high-frequency fluctuations were significantly reduced. The coherence between heart rate and respiration was nearly abolished under vagal blockade in each body posture. We conclude that the increased sympathetic outflow during orthostatic load is reflected by a marked increase in heart rate spectral power densities in the mid-frequency range.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Automatic detection of transient potentials in the EEG].

A classifier based on the linear regression model was developed to automatically detect sharp transients in EEG, matching the definition of spikes and sharp waves accepted by IFSECN. Practical applications proved the accuracy of the method which succeeded in detecting 84% of sharp transients previously found by an experienced electronencephalographer. Computerized search for sharp transients in EEG records will be particularly useful in long term EEG records obtained from epileptic patients.

Computers↗
PubMed1986

[Quantitative EEG analysis of a single dose of psychotropic drugs in healthy probands].

In a series of 74 experiments in a double blind study, 25 healthy test persons were medicated with a single dose of Clomipramin, Desipramin, Imipramin, Diazepam, Carbamazepin, Haloperidol, and a placebo. At the end of one hour, and again at the end of three hours, an EEG was made whose frequency analysis revealed significant changes in about half the test persons. The antidepressives induced an increase in the theta waves, the slow alpha waves, and the slow beta waves, and a decrease in the fast alpha waves. The factors influencing the EEG are discussed.

Adult↗
PubMed1983

[A test for the evaluation of the amplitude distribution of the EEG].

After a critical analysis of the available publications, a new test for the examination of the EEG amplitudes with respect to a normal distribution is presented. By means of autoregressive models, a linear transformation of the EEG to noise signals of a low-degree correlation is carried out, the normal distribution which is studied with respect to obliquenes and excess. In this way, the compromise between the demands for a low scanning frequency, a large extent of random tests and short EEG intervals, which is necessary for the correct application of the adaptation test, is avoided. A total of 82 percent of the tested 40 EEG intervals showed a normal distribution, EEG's with slight general changes being more frequent than alpha-EEG's.

Alpha Rhythm↗