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Biomedical subjects

U Hoppe

Publications and source records attributed to U Hoppe.

At least 19 recordsLinked to original sources
PubMed2003

Vocal fold vibration irregularities caused by different types of laryngeal asymmetry.

The common symptom of hoarseness is regarded to be caused by (1) turbulences and air loss due to incomplete glottic closure and (2) irregular vibrations of the vocal folds. With real time resolution, the latter can only be observed using high-speed recording techniques (> or =2,000 images/s). In this paper an actual recording method is described, called high-speed glottography (HGG), which quantifies vibration irregularities. It combines imaging and image processing techniques with a functional endoscopy of the disordered voice and delivers motion curves separately for each vocal fold. They are fitted with a computer simulation in order to identify the underlying driving parameters of the vibration. A vocal fold is assumed to vibrate as a system of two coupled oscillators ("two-mass model"). From the model fit to bilateral motion curves, the subglottal pressure, muscular tension and oscillating masses of the vocal folds can be computed with reasonable accuracy. Besides normal voices, HGG has been applied to selected clinical cases of voice disorders. Two types of irregularities have been measured: there is a frequency difference either between left and right vocal folds (horizontal asymmetry) or on one side between the ventral and dorsal third (vertical asymmetry). By modeling, both categories of irregular motion curves can be explained in detail. It is presumed that laryngeal asymmetry (either in mass or tension) causes irregular vibrations.

Adult↗
PubMed2003

[Measurement and interpretation of irregular vocal cord fold vibrations].

BACKGROUND: Irregular vibrations of the vocal folds are regarded as a main reason for the common symptom of hoarseness. With real time resolution, they can only be observed using high speed recording techniques (up to 10,000 images/s). METHOD: During the last years, we have developed a recording device and image processing software dedicated to the extraction of vocal fold motion curves from the image series. Irregular vibrations can be understood by using Hirano's "body-cover-model": one vocal fold is assumed to act as a system of two coupled oscillators (the vocal muscle and the epithelium, coupled by the connective tissue of Reinke's space). RESULTS: By applying this biomechanical two-mass model and inversely solving Bernoulli's equation, the driving parameters of the vibration were computed from the high speed image series in selected cases. These parameters, like the subglottal pressure und the bilateral tension of the vocal muscle cannot, in general, be measured directly. DISCUSSION: From the model, it can be supposed that laryngeal asymmetry (either in mass or tension) is the primary reason causing irregularity. The consequence of asymmetry in the medio-lateral direction are different fundamental frequencies on each side, while asymmetry in the anterior-posterior direction leads to ap-mode vibrations.

Diagnosis, Computer-Assisted↗
PubMed2003

[Coping strategies in laryngectomy patients].

BACKGROUND: Over the last few years, paradigms for judging the results of treatment of tumor patients have shifted. In addition to characteristics such as the complete excision of the tumor and the duration of patient survival, restoring the quality of life has become an equally important aim. There is still a lack of systematic (and sufficient) research on coping strategies as a means of dealing with malignant tumors of the head and neck. PATIENTS AND METHOD: In a cross-sectional study, 25 laryngectomees, whose voices had been successfully restored with a Provox voice prosthesis,were examined for their coping strategies and the effects of the illness on their lives. The standardized Trier Scales of Coping Strategies and a custom-made questionnaire, which helped to structure the anamnesis of disease specific functional restrictions and the state of rehabilitation, were used as the means of inquiry. RESULTS: A high percentage of patients were content despite objective and subjective restrictions. Voice replacement was mainly experienced as unproblematic,with psychosocial restraints more commonly being felt in connection with pain and difficulties ingesting food. A correlation between the patients' evaluation of physical,psychological and social experiences and the coping strategies applied could not be verified. The way laryngectomees deal with their illness does not differ from the strategies of patients suffering from malignant or chronic diseases of other organ systems. CONCLUSION: The Trier Scales of Coping Strategies is a suitable means for determining the coping strategies of laryngectomees who have been successfully rehabilitated with the help of voice prostheses. The patients examined here did not apply different coping strategies from groups of patients with other severe illnesses. Obviously, the limitations on communication do not constitute a determining factor in coping with the disease. This finding is useful when planning psychological and social rehabilitation, e.g. by psychosomatic interventions.

Adaptation, Psychological↗
PubMed2003

Normal voice production: computation of driving parameters from endoscopic digital high speed images.

OBJECTIVES: A central point for quantitative evaluation of pathological and healthy voices is the analysis of vocal fold oscillations. By means of digital High Speed Glottography (HGG), vocal fold oscillations can be recorded in real time. Recently, a numerical inversion procedure was developed that allows the extraction of physiological parameters from digital high speed videos and a classification of voice disorders. The aim of this work was to validate the inversion procedure and to investigate the applicability to normal voices. METHODS: High speed recordings were performed during phonation within a group of five female and five male persons with normal voices. By using knowledge based image processing algorithms, motion curves of the vocal folds were extracted at three different positions (dorsal, medial, ventral). These curves were used to obtain physiological voice parameters, and in particular the degree of symmetry of the vocal folds based upon a biomechanical model of the vocal folds. RESULTS: The highest degree of symmetry was observed for the medial motion curves. While the dorsally and ventrally extracted motion curves exhibited similar results concerning the degree of symmetry the performance of the algorithm was less stable. CONCLUSIONS: The inversion algorithm provides reasonable results for all subjects when applied to the medial motion curves. However, for dorsal and ventral motion curves, correct performance is reduced to 85%.

Algorithms↗
PubMed2003

The laryngectomee substitute voice: image processing of endoscopic recordings by fusion with acoustic signals.

OBJECTIVES: The most radical cancer therapy of the throat is the total excision of the larynx which post-operatively results in the loss of voice. A widely-used method of voice rehabilitation is the insertion of a silicone valve, which establishes an unidirectional connection between trachea and esophagus. Thus, during exhalation, air can be directed from the trachea into the esophagus. This air stream excites tissue vibrations of the esophagus and the hypo-pharynx which act as a substitute voice generator. Purpose of the current study is to present a technique for visualizing the dynamics of the substitute voice generating element. METHODS: Digital high speed videos of the vibrating tissue are simultaneously recorded with the emitted acoustic signal. The high speed sequences are directly evaluated by a three-step knowledge based algorithm. It considers correlation between image and acoustic data, information about the gray value of each pixel, and continuity of tissue vibration. The temporal properties of an image series are investigated by evaluating the time dependent gray value at each pixel position. RESULTS: The applicability of the algorithm is exemplarily demonstrated using the data of one male patient. It enables the identification of the regions within an image series which are mainly responsible for the acoustic signal. Additionally, the dynamics of tissue vibrations are visualized. The main propagation direction can be clearly identified. CONCLUSIONS: The new methodology summarizes the information about endoscopic and acoustic recordings of substitute voice into a single image. The results allow a first estimation of tissue velocity and elastic properties of oscillating tissue.

Algorithms↗
PubMed2001

[Interdisciplinary management of chronic tinnitus (II)].

Tinnitus is defined as the perception of sound in the absence of any appropriate external stimulation. It is a common, bothersome and hard-to-evaluate symptom and in most cases it cannot be objectified. Its incidence in Germany and the western world is about 10%. About 1-2% of the population are severely disturbed by tinnitus and it may disrupt everyday activities and sleep. Recent theoretical developments favour a neurophysiological approach as an explanation for tinnitus in addition to a psychoacoustic model based on peripheral lesion in the cochlea or auditory nerve. In the neurophysiological model, the processing of the tinnitus signal plays a dominant role in its detection, perception and evaluation. Therefore, attention and other psychological factors become important in the understanding and treatment of tinnitus. Many treatments of chronic tinnitus have been proposed and implemented. Today, cognitive-behavioural treatment is regarded as an important part of an integrative therapy which may be compiled of counselling, relaxation therapy, instrumental (hearing aid, tinnitus masker, tinnitus instrument, tinnitus noiser) and pharmacological tools (lidocaine, neurotransmitters). In well-controlled studies the empirical support for other therapeutical approaches such as acupuncture is weak. This work gives a review of the current knowledge of the etiology, pathogenesis, epidemiology, the interdisciplinary diagnostic approach and treatment of tinnitus and especially focuses on insurance and medico-legal aspects.

Chronic Disease↗
PubMed2001

[Rare audiometry findings in progressive, monosymptomatic low frequency deafness].

BACKGROUND: Objective audiometric methods such as the measurement of otoacoustic emissions and auditory evoked potentials (click evoked and notched-noise auditory evoked brainstem potentials, auditory evoked cortical potentials) can provide helpful information. However, information derived from the individual test is limited and each method contains specific restrictions. To illustrate the possible audiometric pitfalls this work presents a case history. CASE REPORT: The puretone audiometry showed a severe hearing loss at low frequencies up to 2 kHz, a slight hearing loss for higher frequencies up to 6 kHz and almost normal hearing thresholds above 6 kHz. Transitory evoked otoacoustic emissions could not be detected. While the auditory evoked brainstem responses (ABR) using click-stimuli showed a normal pattern no reproducible responses could be derived using the notched-noise technique. Auditory evoked cortical potentials exhibited a normal N1/P2-complex and were detectable down to stimulus levels 0-20 dB above the individual hearing threshold. DISCUSSION: Click-evoked auditory evoked brainstem potentials are widely regarded as the "gold-standard" of objective audiometry. The example presented in this work shows that in special cases it may provide false negative results. In these special cases auditory tone-evoked cortical potentials may provide better objective information. When objectively assessing the determination of the hearing threshold it may be necessary not only to use all electrophysiological measurements but also to know their methodical restrictions and pitfalls.

Adult↗
PubMed2001

Loudness perception and late auditory evoked potentials in adult cochlear implant users.

In clinical routine the adjustment of speech processors in cochlear implant users is based on the patients' subjective statements about the loudness of specific electrical stimuli. From hearing patients it is known that the latencies and amplitudes of late auditory evoked potentials (LAEP) which are generated within the auditory cortex correlate with the loudness perception of acoustical stimuli. The aim of this study was to investigate the correlation between LAEP and loudness perception in adult cochlear implant users. We investigated 8 adult subjects who had been provided with a 22 electrode Cochlear Implant (nucleus CI24M) at least 6 months prior to the investigation. All subjects showed open speech understanding. Electrical pulse trains of 300 ms duration presented at a single electrode served as stimuli. Electrically LAEP morphologies were similar to normal hearing subjects. In all subjects and each intracochlear electrode position LAEP were well identifiable down to low loudness sensations. Both amplitudes and latencies depended on the loudness perception. The best correlation was observed for the N1 deflection. The results show that LAEP can be used for estimation of both hearing thresholds and most comfortable levels.

Adult↗
PubMed2001

Clinical relevance of distortion product emissions by means of receiver operating characteristic (ROC) analysis.

The clinical use of distortion product otoacoustic emissions (DPOAE) stems from the observation that the outer hair cells are the most vulnerable part of the cochlea, and damage to these cells is associated with hearing loss and loss of DPOAE. The purpose of this study is to evaluate the applicability of DPOAE in predicting hearing thresholds under clinical conditions. DPOAE measurements (L1 = L2 = 70 dB SPL. f2/f1 = 1.20) of 219 hearing-impaired and normal hearing ears were analyzed. Recordings were acquired for DPOAE at 2 f1-f2 varying from 635 to 4052 Hz. The detectability of DPOAE in hearing-impaired subjects exhibited a strong hearing threshold dependence. Receiver operating characteristic (ROC) analysis yielded the highest sensitivity and specificity for threshold levels of about 30 dB at low frequencies and for threshold levels of about 60 dB at high frequencies. In addition, the separability of groups with different hearing status was more reliable at high frequencies as compared to low frequencies. The DPOAE provide an objective assessment of cochlear function. However, prognosis of hearing thresholds on the basis of DPOAE measurements depends strongly on the test frequency and is associated with large errors. Hence, the clinical use of DPOAE in predicting hearing thresholds is limited.

Adult↗
PubMed2001

An automatic sequential recognition method for cortical auditory evoked potentials.

The detection of cortical auditory evoked potentials (CAEP), which are part of the electroencephalogram (EEG) in reaction to acoustic stimuli, has important applications such as determining objective audiograms. The detection is usually performed by a human operator, with support from often basic signal processing methods. This paper presents a novel mechanism for the detection of CAEPs, which is fully automatic and stops the measurement when a given confidence is reached. This proposed detector comprises of three stages. First, a feature extraction by a wavelet transform parameterizes the time domain EEG signal by only few transform coefficients. This feature vector is then classified by a neural network which yields a binary vote on every EEG segment. Finally, a sequential statistical test is performed on successive classifications; this stops the measurement if a specified decision confidence has been reached. The adjustment of the detector according to a clinical database is discussed. Thus adjusted, the proposed CAEP detection scheme is applied to a study, and compared with a human operator. The results demonstrate that this method can attain similar results, but outperforms the human expert for stimulation levels close to the hearing threshold.

Adult↗
PubMed2000

Surgical repair of right-atrial aneurysm.

Atrial fibrillation and embolic events are the most common clinical symptoms of congenital right- or left-atrial aneurysms. We report an a case of righ-atrial aneurysm, in a patient with typical history of atrial fibrillation and history of stroke. The aneurysm was resected, but the patient suffered from acute embolic occlusion of the left anterior descending coronary artery on the fourth postoperative day despite of systemic heparinization with 300 IU/kg bw per 24 hours.

Anticoagulants↗
PubMed1999

Coenzyme Q10, a cutaneous antioxidant and energizer.

The processes of aging and photoaging are associated with an increase in cellular oxidation. This may be in part due to a decline in the levels of the endogenous cellular antioxidant coenzyme Q10 (ubiquinone, CoQ10). Therefore, we have investigated whether topical application of CoQ10 has the beneficial effect of preventing photoaging. We were able to demonstrate that CoQ10 penetrated into the viable layers of the epidermis and reduce the level of oxidation measured by weak photon emission. Furthermore, a reduction in wrinkle depth following CoQ10 application was also shown. CoQ10 was determined to be effective against UVA mediated oxidative stress in human keratinocytes in terms of thiol depletion, activation of specific phosphotyrosine kinases and prevention of oxidative DNA damage. CoQ10 was also able to significantly suppress the expression of collagenase in human dermal fibroblasts following UVA irradiation. These results indicate that CoQ10 has the efficacy to prevent many of the detrimental effects of photoaging.

Antioxidants↗
PubMed1999

[Outcome of hyperbaric oxygen therapy in therapy refractory tinnitus].

Although many studies are available concerning the treatment of sudden deafness using hyperbaric oxygenation, only a few of these deal with tinnitus. The aim of the present study was to evaluate the therapeutic use of hyperbaric oxygenation in cases of tinnitus. A total of 193 patients, having undergone primary intravenous hemorheologic therapy, were treated with hyperbaric oxygenation. Tinnitus was evaluated before, after ten sessions and after 15 sessions using a tinnitus questionnaire. Additionally, an audiometric examination was performed. Measurable improvements of the tinnitus occurred in 22% of the patients, whereas a moderate improvement was seen in 17% of cases. 10.4% showed an excellent improvement and tinnitus disappeared completely in two patients. The improvement rate decreased in those cases where the time from onset of tinnitus exceeded 40 days. In conclusion, hyperbaric oxygenation seems to be a moderately effective additional treatment in the therapy of tinnitus after primary hemorheologic therapy, provided the time from onset of tinnitus is less than 1 month.

Adolescent↗
PubMed1999

[Modulation of oxidative stresses in human aging skin].

Oxidative stress (UV irradiation, free radicals) plays a significant role in aging. Coenzyme Q10 (CoQ10) and exogenously applied antioxidants can significantly reduce the formation of oxidative stress with increasing age. In our in vitro and in vivo experiments concerning the parameters of ultraweak photon emission (UPE), intracellular thiol status, mitochondrial membrane potential and cell vitality, we demonstrated a diminished resistance in keratinocytes of old donors against UV irradiation. This reduced epidermal resistance against oxidative stressors, i.e. UV irradiation, can be improved by topical application of CoQ10 and antioxidants like alpha-glucosylrutin (15). Furthermore, our in vivo investigations show that wrinkles around the region of the eyes ("crow feet") could be reduced by long-term application of CoQ10.

Aged↗
PubMed1999

Two ceramide subfractions detectable in Cer(AS) position by HPTLC in skin surface lipids of non-lesional skin of atopic eczema.

The non-involved skin of atopic eczema (NEAE) is characterized by severe dryness and an impaired barrier function of the stratum corneum as indicated by an increased transepidermal water loss. Previous studies have demonstrated that this barrier impairment coincides with marked alterations in the amount and composition of stratum corneum ceramides. The aim of this study was to identify specific alterations in NEAE that may be used in the diagnosis of the atopic eczema. Using a classical procedure for high performance thin layer chromatography we could confirm earlier results: apart from Cer(EOH), which contains omega-hydroxy fatty acid (O) ester-linked to linoleic acid (E) and amide-linked to 6-hydroxy-4-sphingenine (H), the quantities of all ceramide fractions were significantly decreased. Furthermore, Cer(EOH)/Certotal was significantly increased, whereas the percentage of Cer(EOS), which contains sphingosine (S), and Cer(NP), which contains non-hydroxy fatty acid (N) amide-linked to phytosphingosine (P), were significantly decreased. Using a modified procedure for high performance thin layer chromatography we could demonstrate the formation of a double peak in the position of Cer(AS), which contains alpha-hydroxy fatty acid (A), in lipids of NEAE. The subfractions of the double peak comprised 15% and 12% of Certotal. MALDITOF mass spectrometry suggested that the double peak was formed by a homologous series of mono-hydroxylated and mono-unsaturated ceramides of different chain length, e.g., Cer(AS) subfractions containing either (C16,18) or (C22,24,26) alpha-hydroxy fatty acids. In contrast, in normal skin a single peak in Cer(AS) position, which comprised 22% of Certotal, was mainly formed by the long chain subfraction. In some cases this single peak displayed a small shoulder at its right flank, but never showed a clear peak separation when developed with NEAE samples. Furthermore, even in senile xerosis, or in either non-involved skin of psoriasis or seborrhoic eczema, only a single peak occurred in Cer(AS) position. Accordingly, the double peak might be specific for NEAE and turn out to be a marker for atopic eczema.

Ceramides↗