Biomedical subjects

J Müller

Publications and source records attributed to J Müller.

At least 1,063 records · Page 59Linked to original sources

PubMedDate not supplied

Measurements of ossicular vibrations in the middle ear.

The vibrations of the ossicles were measured with a laser Doppler vibrometer in temporal bone specimens. The data contradicted the generally accepted view that the malleus and incus rotate about a fixed axis. The vibrations of the ossicles show a more complex pattern and, consequently, a more sophisticated model is needed to portray the behaviour of the middle ear in a satisfactory manner. But in turn models with many degrees of freedom make the identification process a very difficult task. This dilemma can be resolved if the system is divided into subsystems of less complexity where each subsystem can be studied in an appropriate manner. The excitation by electrostatic forces, as applied in this study, seems to be a powerful tool to make possible a study of parts of the ossicular chain.

Acoustic Stimulation↗

PubMedDate not supplied

Comparison of the TEMPO+ ear-level speech processor and the cis pro+ body-worn processor in adult MED-EL cochlear implant users.

A study was conducted to compare the new MED-EL TEMPO+ ear-level speech processor with the CIS PRO+ body-worn processor in the COMBI 40/COMBI 40+ implant system. Speech tests were performed in 46 experienced subjects in two test sessions approximately 4 weeks apart. Subjects were switched over from the CIS PRO+ to the TEMPO+ in the first session and used only the TEMPO+ in the time between the two sessions. Speech tests included monosyllabic word tests and sentence tests via the telephone. An adaptive noise method was used to adjust each subject's scores to approximately 50%. Additionally, subjects had to complete a questionnaire based on their 4 weeks of experience with the TEMPO+. The speech test results showed a statistically significant improvement in the monosyllabic word scores with the TEMPO+. In addition, in the second session, subjects showed a significant improvement when using the telephone with the TEMPO+, indicating some learning in this task. In the questionnaire, the vast majority of subjects found that the TEMPO+ allows equal or better speech understanding and rated the sound quality of the TEMPO+ higher. All these objective and subjective results indicate the superiority of the TEMPO+ and are mainly attributed to a new coding strategy called CIS+ and its implementation in the TEMPO+. In other words, based on the results of this study, it appears that after switching over from the CIS PRO+ to the TEMPO+, subjects are able to maintain or even improve their own speech understanding capability.

Adult↗

PubMedDate not supplied

Meningitis following cochlear implantation: pathomechanisms, clinical symptoms, conservative and surgical treatments.

Pneumococcal otogenic meningitis is a rare postsurgical complication that can develop following stapedectomy or after cochlear implantation. The bacterial infection can be fatal in some instances. A recent increase in the incidence of otogenic meningitis among cochlear implant wearers is of concern. The majority of meningitis cases are associated with a 2-component electrode manufactured by one cochlear implant company. The device with the added 'positioner' component has been withdrawn from the market (FDA Public Health Web Notification: Cochlear Implant Recipients may be at Greater Risk for Meningitis, Updated: August 29, 2002, www.fda.gov/cdrh/safety/cochlear.html). Not all cases have been subsequent to otitis media and symptoms have developed from less than 24 h up to a few years after implantation. The purpose of this paper is to review and discuss the pathogenesis, pathology/bacteriology and to elaborate on some clinical features of otogenic meningitis in implanted children and adults. Essential aspects of surgery, electrode design, and cochleostomy seal are discussed. Conclusions are drawn from the available data and recommendations are made for good practice in cochlear implantation and follow-up.

Acute Disease↗

PubMedDate not supplied

Speech understanding in quiet and in noise with the CIS speech coding strategy (MED-EL Combi-40) compared to the multipeak and spectral peak strategies (nucleus).

This study compares sentence understanding in quiet and in noise with 3 different speech coding strategies for cochlear implants. The results show that the spectral-peak (SPEAK) and continuous-interleaved-sampling (CIS) coding strategies, based on spectral signal analysis, allow for better speech understanding in quiet as well as in noise, than the multipeak (MPEAK) coding strategy, which relys on speech feature extraction. In the intrasubject comparison of the MPEAK and SPEAK strategies, the SPEAK coding strategy provided a considerable improvement in quiet and in noise for the majority of patients using the Nucleus 22 Mini-implant. In the intersubject comparisons, the mean results in noise with the CIS strategy were superior to both the MPEAK and the SPEAK strategies. The difference was greatest for the most difficult tests in noise. Understanding in noise was least reduced for the CIS strategy. Understanding in quiet was not significantly different between the CIS and the SPEAK strategies; both strategies were significantly better than the MPEAK strategy in quiet. These results are still preliminary, due to the relatively small number of patients and the great inherent intersubject variability of results.

Adolescent↗

PubMedDate not supplied

Evaluation of performance with the COMBI40 cochlear implant in adults: a multicentric clinical study.

The present multicentric clinical study involves 19 centres, 16 of them in German-speaking countries, 1 British, 1 Polish and 1 Hungarian. 60 postlingually deafened adults with a mean age of 47.5 years (20-70) and mean duration of deafness of 5.3 years (0.5-20) have been evaluated with the MED-EL COMBI 40 cochlear implant which implements a high-rate continuous-interleaved-sampling strategy with 8 channels. Safety and effectiveness data have been collected. Speech perception tests include a 16-consonant, an 8-vowel, a sentence and a monosyllabic-word test in all languages and a 2-digit figure test in all languages but English. Test intervals are 1, 3, 6 months and 1 year after first fitting. 41 of the 60 postlingually deafened adult study patients have completed their 6-month evaluation. While their pre-operative monosyllabic-word score was 0%, their mean monosyllabic-word score 6 months after first fitting was 48% (8-90) with a median of 50%. The mean sentence understanding was 84% (24-100) with a median of 90%. The respective values for the 1-year evaluations with 25 patients are a mean of 50% (5-85), with a median of 60% for the monosyllables and a mean of 89% (30-100), with a median of 97%, for the sentences.

Adult↗

PubMedDate not supplied

Concomitant meniscal and articular cartilage lesions in the femorotibial joint.

The frequency of concomitant meniscal and articular cartilage lesions in the femorotibial joint was analyzed in a retrospective study of 1740 knee joints examined arthroscopically with the objective of determining possible correlations between the two knee joint abnormalities. Articular cartilage lesions were found in 81.4% (N = 1416) of femorotibial joints examined and meniscal derangements were noted in 72.8% (N = 1268). In the medial compartment, concomitance was noted in 76.3% (821 of 1076) on the femoral condyles and in 48.6% (523 of 1076) on the tibial plateau. In the lateral compartment, 43.1% (212 of 492) of the knees with deranged menisci had femoral and 55.1% (271 of 492) had tibial articular lesions. Medial meniscal lesions were more frequently associated with femoral and tibial chondral degeneration than lateral meniscal derangements (P < 0.001). Longitudinal, bucket-handle, and complex tears of the medial meniscus were significantly more often associated with articular cartilage damage than horizontal cleavage, flap, or radial tears. Degeneration of the meniscus was highly correlated with chondral destruction in both compartments. No cause-and-effect relationship could be established, but practical implications of these findings are discussed.

Adolescent↗

PubMedDate not supplied

The structure of the nucleotide-binding site of kinesin.

Kinesin is a microtubule-based motor protein responsible for anterograde transport of vesicles and organelles in nerve axons and other cell types. The energy necessary for this transport is derived from the hydrolysis of ATP which is thought to induce conformational changes in the protein. We have solved the X-ray crystal structures of rat brain kinesin in three conditions intended to mimic different nucleotide states: (1) with ADP bound to the nucleotide-binding site, (2) with bound ADP in the presence of AIF(-)4, and (3) with ADP hydrolyzed to AMP by apyrase. In contrast to analogous cases observed in GTP-binding proteins or the muscle motor myosin, the structure of kinesin remained nearly unchanged. This highlights the stability of kinesin's ADP state in the absence of microtubules. Surprisingly, even after hydrolysis of ADP to AMP by apyrase a strong density peak remains at the position of the beta-phosphate which is compatible either with a phosphate or a sulfate from the solvent and appears to stabilize the nucleotide-binding pocket through several hydrogen bonds.

Adenine Nucleotides↗

PubMedDate not supplied

Anthropometry in skeletal dysplasia.

Skeletal dysplasia or osteochondrodysplasia is the designation of more than 200 different disorders, that are characterized by abnormalities of the skeleton, disproportional short stature, and a variety of other problems. The underlying biochemical defect is unknown in the vast majority of skeletal dysplasias, and the diagnosis is based on radiological findings and anthropometric measurements. Despite this fact, the information on body proportions in even the more common forms of skeletal dysplasia is scarce. Patients with achondroplasia are often diagnosed shortly after birth. Linear growth is severely compromised with relatively short extremities. Head circumference is above normal and final height ranges from 115 to 145 cm in males and 112 to 137 cm in females. Individuals with hypochondroplasia may go unnoticed until puberty, at which time the growth problem becomes obvious. Sitting height to height ratio is increased, but the body disproportion may not be apparent until puberty. Final height has been reported between 118 and 165 cm. Spondyloepiphyseal and spondylometaepiphyseal dysplasias are characterized by severe impairment of growth both in trunk and extremities, and therefore the sitting height to height ratio may be normal. Final height is severely reduced and ranges from 94 to 132 cm. It is concluded that anthropometric studies of patients with skeletal dysplasia are needed. More quantitative information on body proportions may assist in the diagnostic procedure and ensure that growth promoting therapy, e.g. growth hormone, does not worsen the disproportion.

Anthropometry↗

PubMedDate not supplied

Pancreatic phospholipase A2--mediated enhancement of the respiratory burst response of human neutrophils.

The aim of this study was to investigate the effects of exogenously added pancreatic phospholipase A2 (pPLA2) on the production of reactive oxygen species by human polymorphonuclear leukocytes (PMNs). Pancreatic PLA2 was used because PMNs do not possess a receptor for that enzyme and, therefore, the receptor-mediated effects could be excluded. Respiratory burst activity of PMNs was monitored by luminol-amplified chemiluminescence and the lipid composition of neutrophils after treatment with pPLA2 was determined by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. Our results show that the products of the pPLA2 digestion of the PMN membrane--lysophospholipids and the corresponding free fatty acids--significantly enhanced the respiratory burst response of human neutrophils.

Humans↗

PubMedDate not supplied

Noninvasive direct stimulation of the cochlear nerve for functional MR imaging of the auditory cortex.

We herein present our preliminary experience with functional MR imaging of the direct electrical stimulation of the cochlear nerve using an MR imaging-compatible electrode placed in the external auditory meatus of five patients with binaural sensorineural hearing loss. The stimulator was placed outside the imager's bore, and the electrode produced virtually no susceptibility artifacts. In three of five patients, it was possible to activate the superior temporal gyrus during functional MR imaging. No side effects were observed.

Auditory Cortex↗

PubMedDate not supplied

Clinical heart transplantation without routine endomyocardial biopsy.

In a prospective clinical study, routine endomyocardial biopsy (EMB) for early detection of cardiac allograft rejection was replaced by two noninvasive diagnostic techniques. In 32 patients who underwent transplantation during a 6-month period, intramyocardial electrogram (IMEG) amplitude was recorded with the telemetry function of a dual-chamber pacemaker system. An amplitude decrease of more than 8% below the individual range of variability in overnight long-term recordings served as an indicator of rejection. A prolongation of the time interval Te--the time span between maximal posterior wall contraction and peak retraction velocity--of more than 20 msec was used as an additional indicator of rejection-related left ventricular dysfunction. For patient safety, routine EMBs were still performed but remained undisclosed to the transplantation team. The pathologist was asked to intervene in cases of discrepancies between biopsy results and medical decisions, but no such intervention was necessary. Twenty-seven rejection episodes were treated medically, of which 22 were diagnosed noninvasively. In four patients, EMB, ordered because noninvasive parameters remained inconclusive, led to medical treatment. No false negative IMEG results were observed. Retrospective correlation with rejection gave a 100% negative predictive value for IMEG and a 96.9% negative predictive value for echocardiographic diagnosis. We conclude that omission of a schedule of routine biopsies is justified, if the described techniques of IMEG and echocardiography are meticulously applied and indicate normal cardiac function. EMB remains indicated if noninvasive parameters are not conclusive or if false-positive IMEG results, which were observed in the presence of infection or arrhythmias, are suspected. The frequency of EMB can be reduced by 90%, compared to conventional routine biopsy schedules. Diagnostic safety is increased because the additional information gained from IMEG and echocardiography is helpful in the interpretation of EMBs.

Biopsy↗

PubMedDate not supplied

[Intensive treatment of respiratory failure--personal experiences].

Controlled oxygen-therapy was used in 30 out of 49 patients (61%) with the acute respiratory failure or exacerbations of the chronic respiratory failure treated at ICU (Group Y), while artificial ventilation in the remaining 19 patients (39%; Group B). An improvement was achieved in 70% of patients of Group A and 42% in Group B. Overall improvement was achieved in 59% of the treated patients. There were 69% of treated patients with infections. Totally 41% of the treated patients died (30% of Group A and 58% of Group B). An analysis of the results has been carried out in various subgroups of the treated patients, i.e. the acute and exacerbated respiratory failure as well as partial and complete respiratory insufficiency. The result of high risk patients have also been analysed. This subgroup included sudden cardiac arrest, shock and non-compensated acidosis. Favourable effects of the intensive care of patients with infections have been discussed with particular reference to the life hazard in case of septic complications. Emphasis is on the unfavorable effects of therapy in patients with respiratory failure complicated with pulmonary embolism. Indications to the use of respirator and complications of the artificial ventilation have been discussed.

Bicarbonates↗

PubMedDate not supplied

[Respiratory failure treated at the intensive care unit "R" of the Internal Disease Clinic of the Institute of Tuberculosis and Pulmonary Diseases (1986-1987)].

A picture and clinical course of the acute and exacerbated chronic respiratory failure have been analysed. An analysis embraced a group of 49 patients, i.e. 16 percent of all patients treated at the Intensive Care Unit. Four subgroups were distinguished depending on the etiology of the disease in which infectious, thrombo-embolic, circulatory or toxic factors caused respiratory failure. An emphasis is on the prevalence of the infectious etiology of disease being noted in 65% of patients. Acute respiratory failure was observed in 37% of patients whereas exacerbation of the chronic respiratory failure in 63%. Complete respiration distress was noted in 55% of cases and partial respiratory failure in the remaining 45%. Gasometric differences characteristic for each subgroup of the patients have also been analysed. 41% of the patients died. The highest mortality rate was seen in pulmonary embolism complicating various pulmonary diseases. Sudden cardiac arrest, shock and not compensated acidosis have been most unfavourable factors in the prognosis.

Adolescent↗

PubMedDate not supplied

[Skewed shape of the maximal expiratory flow volume curve and bronchoscopic signs of lower airway collapse in chronic obstructive pulmonary disease].

We compared endoscopical signs of airway collapse seen during tidal breathing with the shape of the maximal-expiratory flow volume curve and selected functional parameters in 16 cases of chronic obstructive pulmonary disease (COPD). Depending on localization of airway collapse the group was divided into two. 12 patients with central collapse involving the trachea and main stem bronchi formed group A. The remaining 4 patients with peripheral collapse (lobar and segmental bronchi) formed group B. In the former group the MEFV curve had a characteristic biphasic shape. The shape of this curve in the group B patients was more curvilinear. In group A patients an increase of Raw, TGV and fall of FEV1 was seen which could not be demonstrated in group B. The biphasic shape of the MEFV curve seems to be characteristic of airway collapse, but due to a small number of patients included we can not assess the specificity of it in diagnosing airway collapse.

Adult↗

PubMedDate not supplied