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Biomedical subjects

M Rogowski

Publications and source records attributed to M Rogowski.

31 records · Page 2Linked to original sources
PubMed1995

Morphologic study of the guinea pig cochlea after cochlear implantation using the "soft surgery" technique.

Clinical and experimental data appear to indicate that by means of an extremely gentle procedure, known as the "soft surgery" technique, during the insertion of the electrode carrier of the cochlear implant, some level of existing residual hearing can be preserved. By means of an animal model, morphologic changes in the organ of Corti after use of this atraumatic implantation technique were investigated with two types of implants and the results compared. Insertion of the implants was facilitated by lubrication with Healon. In the scanning electron microscopy picture of the organ of Corti, only minor changes in the outer hair cells were observed. As an obligatory reaction of the cochlea to the intracochlear implant, a connective tissue envelope was found around the electrode carrier.

Animals↗
PubMed1994

Detection of cochlear dysfunction by the measurement of transiently evoked otoacoustic emissions in guinea pigs with autoimmune-induced labyrinthitis.

For the evaluation of functional inner ear lesions caused by an autoimmune-induced labyrinthitis, transiently evoked otoacoustic emissions (TEOAEs) were detected in guinea pigs before and after transfer of sensitized lymphocytes from animals suffering from a labyrinthitis induced by the foreign protein keyhole limpet hemocyanin (KLH). Initially TEOAEs were detectable from 47 of 62 ears (76%) in healthy guinea pigs. These animals then were used as recipients for sensitized lymphocytes from donors exclusively. Three months after cell transfer the incidence of TEOAEs was reduced to 48% in animals receiving lymphocytes from donors sensitized with KLH intradermally and intracochlearly. In recipients of lymphocytes from donors sensitized only intradermally and in untreated animals no significant alteration of the TEOAE incidence was found. These findings showed strong correlation with those from scanning electron microscopy of the organ of Corti, indicating that the measurement of TEOAE is a useful, time-saving tool for the detection of cochlear dysfunction caused by sensitized lymphocytes in experimental animal. The present findings also show that the migration of sensitized lymphocytes actually leads to functional lesions in the cochlea.

Animals↗
PubMed1994

Adoptive transfer of an autoimmunological labyrinthitis in the guinea pig; animal model for a sympathetic cochleolabyrinthitis.

Sensorineural hearing loss is a common problem in the otolaryngologist's practice, with autoimmune disease of the inner ear being one possible cause. The restoration of auditory function in some patients following immunosuppressive therapy has created a desire to define and understand this disease better. Because of the lack of a well defined detection method to identify this entity clinically, this study was undertaken in order to provide an animal model for autoimmune disease of the inner ear. Previous studies with guinea pigs have demonstrated that sensitized lymphocytes from the systemic circulation migrate to the labyrinth during an immune response in the inner ear. The aim of this study was to prove the capacity of sensitized lymphocytes to transfer autoimmune inner ear disease, and to describe the resulting morphological and physiological changes. Therefore two groups of sensitized lymphocytes partially labelled with a radioactive marker from inbred guinea pigs with an immune response within the inner ear were injected into the bloodstream of naive recipient animals. Most of the labelled cells were observed in the apical turn of the experimental cochlea, while only few cells were detectable in the control cochleas. In addition, the absence of otoacoustic emissions and the loss of outer hair cells observed by electron microscopy were interpreted as a sign of damage caused by the provoked immunopathologic mechanism. The results are discussed as a possible model for a sympathetic cochleolabyrinthitis.

Animals↗
PubMed1994

[Experimental perilymphatic fistula].

The round window membrane of the inner ear of 15 guinea pigs was removed under ketamine anaesthesia. Perilymph was aspirated through the round window in 8 guinea pigs. The round window membrane had regenerated spontaneously after 2 weeks. Light microscopy revealed hair cell loss localized to the apical and basal turns of the cochlea. Morphological examinations showed the most severe changes in these group of aspirated animals. Abrupt pressure imbalance may be a causative factor of sensorineural hearing loss.

Animals↗
PubMed1994

[Pseudo-three dimensional observation of the organ of Corti in the guinea pig using scanning electron microscopy].

The entire organ of Corti of guinea pig was investigated by scanning electron microscopy (SEM), using it's high resolving power to observe the three dimensional fine structure of the cochlea. Inner ear tissue of the normal guinea pig was conductively stained (OTOTO-method) for SEM. The relationship between the sensory cells and supporting cells was shown. SEM gives a nice overview of the surface structure of three dimensional organs like the inner ear. We conclude that bulk specimens of the organ of Corti are more advantageous than piece specimens in acoustic physiological as well as pathological research studies.

Animals↗
PubMed1989

[The lymphocyte transformation test for detecting immunologic inner ear deafness].

The basis and performance of the lymphocyte transformation test for proving an immunologically induced inner ear hearing loss are described and documented. In 6 out of 14 patients with inner ear hearing loss of unknown origin an immunological etiology could be elaborated by using this test. The relevance of this test as well and its further application by using collagen type II as antigen are discussed.

Adolescent↗
PubMed1989

[Evaluation of hearing in patients with diabetes].

Hearing in 60 diabetics aged 20-70 years were studied by means of tonal, verbal and B'ekèsy audiometry, SISI tests, Fowler tests, stapedius reflex and tone decay tests. The material was grouped according to the diabetes type, chronicity of disease, age, sex and presence of retino- and polyneuropathy. The results proved that diabetes may cause the progressive form of hearing loss which depend of chronicity of disease and age of patients. Sometimes the hypo-acuity may be found in the recent form of diabetes, rarely as sudden deafness. The hearing impairment is more frequent among the retino- and polyneuropathy patients. The localisation of lesions may be in all part of hearing pathways from the labyrinth to cortical areas.

Adult↗
PubMedDate not supplied

Using a CFD model to understand the fluid dynamics promoting E. coli breakage in a high-pressure homogenizer.

A Computational Fluid Dynamic (CFD) model of flow in a high-pressure homogenizing valve (APV Gaulin model 30CD) was developed with the Fluent software. The 2D model consists of an unstructured hexagonal mesh, dense in the regions of high gradients. The flow (single-phase) was modeled as laminar upstream of and in the channel (gap) and turbulent downstream of the channel exit. Applying a realizable kappa-epsilon turbulence model, the CFD model accurately predicted the effect of gap space on fluid dynamic conditions upstream (inlet pressure and pressure gradient) and downstream (impact pressure) of the channel for a valve with a standard (CD-0) impact distance (0.25 mm) and a 1 cP fluid. This CFD model was then used to estimate the magnitude of the fluid dynamic parameters (except cavitation effects) presumed to be responsible for cell breakage, as a function of gap space, impact distance and fluid viscosity. The CFD models predicted that for a given volumetric flowrate the upstream fluid conditions (inlet pressure gradient, maximum channel strain rate) and the maximum energy dissipation rate in the post-gap jet depend only on the gap space and the fluid viscosity and not on the impact distance. The impact pressure however depends on the gap spacing, the fluid viscosity and especially the impact distance. Experimental results indicate that higher inlet pressures are required to break cells, if the impact distance is increased. By conducting experiments to isolate individual cell breakage mechanisms for a single pass, threshold values were identified for breaking Escherichia coli cells: pressure gradient, 1.2 x 10(12) Pa/m; energy dissipation rate, 1.0 x 10(10) m(3)/s(2); and impact pressure, 160 psig. By isolating the wall impact as the sole mechanism responsible for breaking the E. coli cells between 3000 and 6000 psig inlet pressure, a relationship between E. coli cell breakage rate and maximum wall impact pressure was established (eq 5).

Cell Fractionation↗
PubMedDate not supplied

[The importance of brain stem evoked potentials in the diagnosis of neurosurgical patients].

The technique of Brainstem Electric Response Audiometry (BERA) is a non-invasive electrophysiologic method used in comatose patients for localization of areas of neuronal and synaptic dysfunction not evident in clinical evaluation. This test has a diagnostic and prognostic value in detection of abnormalities and evaluation of comatose head-injured patients at a reversible clinical stage. In contrast to most clinical signs, brainstem auditory evoked potentials are independent of levels of consciousness, analgesics, sedatives. This test is aetiologically non-specific and must be carefully integrated into the clinical situation. Generators of brainstem auditory evoked potentials are located in the auditory nerve (waves I and II) and brainstem (waves III-V). Patients in acute posttraumatic coma are assessed by means of Glasgow Coma Score (GCS), which is reliable in forecasting a favourable outcome. Patients with a score 8 points have an unfavourable outcome in 16%. Brainstem auditory evoked potentials are reliable predictors of unfavourable outcome. Subsequent brainstem auditory evoked potential testing provides relevant prognostic information, since improvement of graded brainstem auditory evoked potentials indicates a favourable outcome. Progressive deterioration of brainstem auditory evoked potentials indicates irreversible damage and is associated with unfavourable outcome, whereas singular abnormal evoked potentials may result from reversible neuronal dysfunction. The absence of waves III-V associated with the end EEG activity is the proof of brain death. Serial BERA monitoring has been used to evaluate progressive clinical syndromes, such as "uncal herniation" and evolving brain death. The use of serial BERA recordings appeared to improve the outcome predictions in comparison with single BERA tests. A combination of brainstem auditory evoked potentials, somatosensory and visual evoked potentials (multimodality evoked potentials-MEP) provides more information for management of a patient than a single evoked potential modality. The main goal to use BERA is early detection of secondary deterioration in comatose patients suffering from intracranial lesions. The results of brainstem auditory evoked potentials and clinical examination of patients obtained within the acute phase after head injury may indicate increased intracranial pressure (ICP) and incipient transtentorial herniation but do not always predict outcome (GOS). The outcome can be better evaluated later, 3-6 days after head injury. In summary, BERA is a non-invasive, safe and objective method of evaluating patients after severe head injury and adds valuable information for assessment of their outcome.

Brain Stem↗