[Online training for hearing implant surgery : A new approach to otological training. German version]

OBJECTIVE

Education in microsurgery of the ear includes staged training to allow for mastering of the complex microsurgical procedures, particularly in the context of middle ear reconstruction and cochlear implantation. Traditional surgical training includes temporal bone preparations by cadaver dissection and supervised operating room practice. As these on-site trainings are limited, there is a need to broaden education facilities in an on-line format. Therefore, a first basic on-line training for otosurgery was developed.

MATERIALS AND METHODS

The system consists of an artificial temporal bone model together with a set of basic surgical instruments and implant dummies. As an essential part of the training kit, a high-resolution camera set is included that allows for connection to a video streaming platform and enables remote supervision of the trainees' surgical steps by experienced otological surgeons. In addition, a pre-learning platform covering temporal bone anatomy and instrumentation and pre-recorded lectures and instructional videos has been developed to allow trainees to review and reinforce their understanding before hands-on practice.

RESULTS

Over the three courses held to date, 28 participants with varying levels of prior surgical experience took part in this otological surgical training program. The immediate feedback of the participants was evaluated by means of a questionnaire. On this basis, the high value of the program became apparent and specific areas could by identified where further refinements could lead to an even more robust training experience.

CONCLUSION

The presented program of an otosurgical online training allows for basal education in practical exercises on a remote system. In this way, trainees who have no direct access to on-site instruction facilities in ear surgery now have the chance to start their otosurgical training in an educational setting adapted to modern technologies.

[Comprehensive literature review on the application of the otological-surgical planning software OTOPLAN® for cochlear implantation. German version]

BACKGROUND

The size of the human cochlear, measured by the diameter of the basal turn, varies between 7 and 11 mm. For hearing rehabilitation with cochlear implants (CI), the size of the cochlear influences the individual frequency map and the choice of electrode length. OTOPLAN® (CAScination AG [Bern, Switzerland] in cooperation with MED-EL [Innsbruck, Austria]) is a software tool with CE marking for clinical applications in CI treatment which allows for precise pre-planning based on cochlear size. This literature review aims to analyze all published data on the application of OTOPLAN®.

MATERIALS AND METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were applied to identify relevant studies published in the PubMed search engine between January 2015 and February 2023 using the search terms "otoplan" [title/abstract] OR "anatomy-based fitting" [title/abstract] OR "otological software tool" [title/abstract] OR "computed tomography-based software AND cochlear" [title/abstract].

RESULTS

The systematic review of the literature identified 32 studies on clinical use of OTOPLAN® in CI treatment. Most studies were reported from Germany (7 out of 32), followed by Italy (5), Saudi Arabia (4), the USA (4), and Belgium (3); 2 studies each were from Austria and China, and 1 study from France, India, Norway, South Korea, and Switzerland. In the majority of studies (22), OTOPLAN® was used to assess cochlear size, followed by visualizing the electrode position using postoperative images (5), three-dimensional segmentation of temporal bone structures (4), planning the electrode insertion trajectory (3), creating a patient-specific frequency map (3), planning of a safe drilling path through the facial recess (3), and measuring of temporal bone structures (1).

CONCLUSION

To date, OTOPLAN® is the only DICOM viewer with CE marking in the CI field that can process pre-, intra-, and postoperative images in the abovementioned applications.

[Repetitio est mater studiorum-implementation of ENT cases in case-based e-learning]

BACKGROUND

German university otorhinolaryngology has a need for digital teaching content. Case-based e‑learning represents a digital teaching methodology. The data on student use of case-based e‑learning in university teaching of ENT medicine are limited.

OBJECTIVE

The aim of this work was to determine the extent to which voluntary case-based e‑learning is used by otolaryngology students and what influence the quality of the e‑learning has on motivation to use e‑learning and on the interest in otolaryngology.

MATERIALS AND METHODS

Fifteen voluntary e‑learning cases were created based on the content of the ENT lecture in the winter semester 2022/2023. Subsequently, a descriptive evaluation of the usage statistics of the cases of 157 students was conducted. Likewise, an evaluation of the quality of the e‑learning as well as the motivation to complete it and the interest in otorhinolaryngology was carried out using a voluntary questionnaire.

RESULTS

Voluntary case-based e‑learning was used to varying degrees by 66% of the students. The quality of e‑learning correlated significantly with the motivation and the interest in otolaryngology.

CONCLUSION

The teaching content of otorhinolaryngology can be implemented sufficiently in case-based e‑learning and is characterized by satisfactory student acceptance. Integration should be accomplished in a high-quality manner to increase motivation and interest in otorhinolaryngology.

Adult Neurogenesis of the Medial Geniculate Body: In Vitro and Molecular Genetic Analyses Reflect the Neural Stem Cell Capacity of the Rat Auditory Thalamus over Time

Neural stem cells (NSCs) have been recently identified in the neonatal rat medial geniculate body (MGB). NSCs are characterized by three cardinal features: mitotic self-renewal, formation of progenitors, and differentiation into all neuroectodermal cell lineages. NSCs and the molecular factors affecting them are particularly interesting, as they present a potential target for treating neurologically based hearing disorders. It is unclear whether an NSC niche exists in the rat MGB up to the adult stage and which neurogenic factors are essential during maturation. The rat MGB was examined on postnatal days 8, 12, and 16, and at the adult stadium. The cardinal features of NSCs were detected in MGB cells of all age groups examined by neurosphere, passage, and differentiation assays. In addition, real-time quantitative polymerase chain reaction arrays were used to compare the mRNA levels of 84 genes relevant to NSCs and neurogenesis. In summary, cells of the MGB display the cardinal features of NSCs up to the adult stage with a decreasing NSC potential over time. Neurogenic factors with high importance for MGB neurogenesis were identified on the mRNA level. These findings should contribute to a better understanding of MGB neurogenesis and its regenerative capacity.

[Initial assessment of ENT emergencies-a feasibility study]

In Germany, an increased volume of patient cases in the emergency department has been observed for several years, many of which do not represent hospital emergencies. To improve the triage and management of patient flows, the Structured Initial Medical Assessment (Strukturierte medizinische Ersteinschätzung in Deutschland, SmED) triage system was developed. This certified medical product is intended to assess both the urgency of everyday complaints and their adequate medical care in a targeted, faster, and safer manner. It supports medical professionals in triage by suggesting courses of action, whereby the ultimate responsibility remains with the professionals themselves. For otorhinolaryngology, a content review was carried out with regard to plausibility and patient safety in the head and neck region on the basis of nine specific emergencies. The cases were simulated by nine otorhinolaryngologists and triaged on the basis of the SmED by medical staff and medical students by assigning a care level and timepoint (urgency). The majority of cases were correctly assigned. The SmED initial assessment system is a good tool for assessing urgent clinical pictures in ear, nose, and throat (ENT) medicine. The long-term goal of the initial assessment is to relieve the capacities of outpatient departments. In order to achieve this and to shorten patient waiting times, it would be necessary to refer patients quickly to otorhinolaryngology. It is therefore necessary to ensure that patients are referred to an ENT on-call service via the online tool.

The Stapes Head Coupler-A Flexible and Safe Option for Vibroplasty

OBJECTIVE

To investigate the surgical approach and the audiological outcome of a stapes head coupler in active middle ear implant surgery.

STUDY DESIGN

Retrospective data analysis.

SETTING

Tertiary referral center with a large active middle ear implant program.

PATIENTS

Twelve patients with active middle ear implant surgery.

INTERVENTIONS

Therapeutic surgical approach for hearing rehabilitation in human subjects.

MAIN OUTCOME MEASURES

Auditory brainstem response, sound field thresholds, vibrogram, speech perception in the Freiburger monosyllabic word test.

RESULTS

The stapes head was attached safely in different coupling situations. Audiological outcomes were similar to the audiological performance of established vibroplasty couplers presented in the literature.

CONCLUSION

The stapes head coupler is a new and safe tool for vibroplasty with a good audiological outcome.

Computed tomographic 3D analysis of the cochlear aqueduct-potential and limitations of clinical imaging

Background: The cochlear aqueduct (CA), which connects the scala tympani and the subarachnoid space, and its accompanying structures appear to have a significant relevance during cochlear implantation and an accurate visualization in clinical imaging is of great interest. Aims and Objective: This study aims to determine which potential and limitations clinically available imaging modalities have in the visualization of the CA. Methods: Micro-CT, flat-panel volume computed tomography with and without secondary reconstruction (fpVCT, fpVCTseco) and multislice computed tomography (MSCT) of 10 temporal bone specimen were used for 3D analysis of the CA. Results: FpVCTseco proved superior in visualizing the associated structures and lateral portions of the CA, which merge into the basal turn of the cochlea. All clinical imaging modalities proved equal in analyzing the length, total volume of the CA and its area of the medial orifice. Conclusion: The choice of the most accurate clinical imaging modality to evaluate the CA and its associated structures depends on the clinical or scientific question. Furthermore, this study should provide a basis for further investigations analyzing the CA.

mRNA Abundance of Neurogenic Factors Correlates with Hearing Capacity in Auditory Brainstem Nuclei of the Rat

Neural stem cells (NSCs) have previously been described up to the adult stage in the rat cochlear nucleus (CN). A decreasing neurogenic potential was observed with critical changes around hearing onset. A better understanding of molecular factors affecting NSCs and neurogenesis is of interest as they represent potential targets to treat the cause of neurologically based hearing disorders. The role of genes affecting NSC development and neurogenesis in CN over time on hearing capacity has remained unclear. This study investigated the mRNA abundance of genes influencing NSCs and neurogenesis in rats' CN over time. The CN of rats on postnatal days 6, 12, and 24 were examined. Real-time quantitative polymerase chain reaction arrays were used to compare mRNA levels of 84 genes relevant to NSCs and neurogenesis. Age- and hearing-specific patterns of changes in mRNA abundance of neurogenically relevant genes were detected in the rat CN. Additionally, crucial neurogenic factors with significant and relevant influence on neurogenesis were identified. The results of this work should contribute to a better understanding of the molecular mechanisms underlying the neurogenesis of the auditory pathway.

Neurogenic Stem Cell Niche in the Auditory Thalamus: In Vitro Evidence of Neural Stem Cells in the Rat Medial Geniculate Body

The medial geniculate body (MGB) is a nucleus of the diencephalon representing a relevant segment of the auditory pathway and is part of the metathalamus. It receives afferent information via the inferior brachium of the inferior colliculus and transmits efferent fibers via acoustic radiations to the auditory cortex. Neural stem cells (NSCs) have been detected in certain areas along the auditory pathway. They are of great importance as the induction of an adult stem cell niche might open a regenerative approach to a causal treatment of hearing disorders. Up to now, the existence of NSCs in the MGB has not been determined. Therefore, this study investigated whether the MGB has a neural stem cell potential. For this purpose, cells were extracted from the MGB of PND 8 Sprague-Dawley rats and cultured in a free-floating cell culture assay, which showed mitotic activity and positive staining for stem cell and progenitor markers. In differentiation assays, the markers β-III-tubulin, GFAP, and MBP demonstrated the capacity of single cells to differentiate into neuronal and glial cells. In conclusion, cells from the MGB exhibited the cardinal features of NSCs: self-renewal, the formation of progenitor cells, and differentiation into all neuronal lineage cells. These findings may contribute to a better understanding of the development of the auditory pathway.

Accuracy of radiological prediction of electrode position with otological planning software and implications of high-resolution imaging

OBJECTIVES

In cochlear implantation, preoperative prediction of electrode position has recently gained increasing attention. Currently, planning is usually done by multislice CT (MSCT). However, flat-panel volume CT (fpVCT) and its secondary reconstructions (fpVCTSECO) allow for more precise visualization of the cochlea. Combined with a newly developed otological planning software, the position of every single contact can be effectively predicted. In this study it was investigated how accurately radiological prediction forecasts the postoperative electrode localization and whether higher image resolution is advantageous.

METHODS

Utilizing otological planning software (OTOPLAN®) and different clinical imaging modalities (MSCT, fpVCT and fpVCTSECO) the electrode localization [angular insertion depth (AID)] and respective contact frequencies were predicted preoperatively and examined postoperatively. Furthermore, inter-electrode-distance (IED) and inter-electrode-frequency difference (IEFD) were evaluated postoperatively.

RESULTS

Measurements revealed a preoperative overestimation of AID. Corresponding frequencies were also miscalculated. Determination of IED and IEFD revealed discrepancies at the transition from the basal to the middle turn and round window to the basal turn. All predictions and discrepancies were lowest when using fpVCTSECO.

CONCLUSION

The postoperative electrode position can be predicted quite accurately using otological planning software. However, because of several potential misjudgments, high-resolution imaging, such as offered by fpVCTSECO, should be used pre- and postoperatively.

Pegylated Insulin-Like Growth Factor 1 attenuates Hair Cell Loss and promotes Presynaptic Maintenance of Medial Olivocochlear Cholinergic Fibers in the Cochlea of the Progressive Motor Neuropathy Mouse

The progressive motor neuropathy (PMN) mouse is a model of an inherited motor neuropathy disease with progressive neurodegeneration. Axon degeneration associates with homozygous mutations of the TBCE gene encoding the tubulin chaperone E protein. TBCE is responsible for the correct dimerization of alpha and beta-tubulin. Strikingly, the PMN mouse also develops a progressive hearing loss after normal hearing onset, characterized by degeneration of the auditory nerve and outer hair cell (OHC) loss. However, the development of this neuronal and cochlear pathology is not fully understood yet. Previous studies with pegylated insulin-like growth factor 1 (peg-IGF-1) treatment in this mouse model have been shown to expand lifespan, weight, muscle strength, and motor coordination. Accordingly, peg-IGF-1 was evaluated for an otoprotective effect. We investigated the effect of peg-IGF-1 on the auditory system by treatment starting at postnatal day 15 (p15). Histological analysis revealed positive effects on OHC synapses of medial olivocochlear (MOC) neuronal fibers and a short-term attenuation of OHC loss. Peg-IGF-1 was able to conditionally restore the disorganization of OHC synapses and maintain the provision of cholinergic acetyltransferase in presynapses. To assess auditory function, frequency-specific auditory brainstem responses and distortion product otoacoustic emissions were recorded in animals on p21 and p28. However, despite the positive effect on MOC fibers and OHC, no restoration of hearing could be achieved. The present work demonstrates that the synaptic pathology of efferent MOC fibers in PMN mice represents a particular form of “efferent auditory neuropathy.” Peg-IGF-1 showed an otoprotective effect by preventing the degeneration of OHCs and efferent synapses. However, enhanced efforts are needed to optimize the treatment to obtain detectable improvements in hearing performances.

Spontaneous Calcium Oscillations through Differentiation: A Calcium Imaging Analysis of Rat Cochlear Nucleus Neural Stem Cells

Causal therapies for the auditory-pathway and inner-ear diseases are still not yet available for clinical application. Regenerative medicine approaches are discussed and examined as possible therapy options. Neural stem cells could play a role in the regeneration of the auditory pathway. In recent years, neural stem and progenitor cells have been identified in the cochlear nucleus, the second nucleus of the auditory pathway. The current investigation aimed to analyze cell maturation concerning cellular calcium activity. Cochlear nuclei from PND9 CD rats were microscopically dissected and propagated as neurospheres in free-floating cultures in stem-cell medium (Neurobasal, B27, GlutaMAX, EGF, bFGF). After 30 days, the dissociation and plating of these cells took place under withdrawal of the growth factors and the addition of retinoic acid, which induces neural cell differentiation. Calcium imaging analysis with BAPTA-1/Oregon Green was carried out at different times during the differentiation phase. In addition, the influence of different voltage-dependent calcium channels was analyzed through the targeted application of inhibitors of the L-, N-, R- and T-type calcium channels. For this purpose, comparative examinations were performed on CN NSCs, and primary CN neurons. As the cells differentiated, a significant increase in spontaneous neuronal calcium activity was demonstrated. In the differentiation stage, specific frequencies of the spontaneous calcium oscillations were measured in different regions of the individual cells. Initially, the highest frequency of spontaneous calcium oscillations was ascertainable in the maturing somata. Over time, these were overtaken by calcium oscillations in the axons and dendrites. Additionally, in the area of the growth cones, an increasing activity was determined. By inhibiting voltage-dependent calcium channels, their expression and function in the differentiation process were confirmed. A comparable pattern of maturation of these channels was found in CN NSCs and primary CN neurons. The present results show that neural stem cells of the rat cochlear nucleus differentiated not only morphologically but also functionally. Spontaneous calcium activities are of great relevance in terms of neurogenesis and integration into existing neuronal structures. These functional aspects of neurogenesis within the auditory pathway could serve as future targets for the exogenous control of neuronal regeneration.

Implementation of secondary reconstructions of flat-panel volume computed tomography (fpVCT) and otological planning software for anatomically based cochlear implantation

Purpose

For further improvements in cochlear implantation, the measurement of the cochlear duct length (CDL) and the determination of the electrode contact position (ECP) are increasingly in the focus of clinical research. Usually, these items were investigated by multislice computed tomography (MSCT). The determination of ECP was only possible by research programs so far. Flat-panel volume computed tomography (fpVCT) and its secondary reconstructions (fpVCT_SECO) allow for high spatial resolution for the visualization of the temporal bone structures. Using a newly developed surgical planning software that enables the evaluation of CDL and the determination of postoperative ECP, this study aimed to investigate the combination of fpVCT and otological planning software to improve the implementation of an anatomically based cochlear implantation.

Methods

Cochlear measurements were performed utilizing surgical planning software in imaging data (MSCT, fpVCT and fpVCT_SECO) of patients with and without implanted electrodes.

Results

Measurement of the CDL by the use of an otological planning software was highly reliable using fpVCT_SECO with a lower variance between the respective measurements compared to MSCT. The determination of the inter-electrode-distance (IED) between the ECP was improved in fpVCT_SECO compared to MSCT.

Conclusion

The combination of fpVCT_SECO and otological planning software permits a simplified and more reliable analysis of the cochlea in the pre- and postoperative setting. The combination of both systems will enable further progress in the development of an anatomically based cochlear implantation.

Button batteries and typical swallowed foreign bodies can be differentiated in high-resolution X-Rays

BACKGROUND

Button battery ingestions have emerged as an increasing medical issue in recent years, especially for children. The frequent use of these energy sources in small appliances and toys is responsible for their ubiquitous occurrence in households. In addition to other possible foreign bodies, button batteries are particularly dangerous as they can cause severe complications in the aerodigestive tract.

OBJECTIVE

The study aimed for a detailed analysis of specific radiographic identifiers of button batteries and similarly configured potential esophageal foreign bodies in high-resolution X-ray scans.

METHODS

A selection of potentially hazardous button batteries - in cases of ingestion (CR2032) or aspiration (LR44, LR1130) - was made. Other clinically relevant radio-opaque objects of similar size and shape have been selected accordingly. High-resolution X-ray scans (33.3 lp/mm) were made using an in vitro model in porcine esophageal preparations. A systematic, comparative analysis was carried out with the digital radiographic images.

FINDINGS

In the study described, the selected foreign bodies were scanned at distinct angles in high image quality. Using button batteries, radiographically details of their internal structures were shown that have not yet been described. The known markers, as well as new detailed characteristics, were found in the experimental setting. The differentiation from other typical esophageal foreign bodies was possible by analyzing four relevant identification features: the edge properties, internal structures, the size, and differences in 0°/90° scans.

CONCLUSIONS

The study results reveal that specific features of potential esophageal foreign bodies can be identified by improved radiographic resolution, contrast, and dynamics. Thus, the diagnostic reliability in distinguishing 'high-risk foreign bodies' from less dangerous ones could be increased. In the future, button batteries could be detected more reliably with intelligent digital image analysis and enhanced radiographic technology. This may further support clinical triage algorithms and help reduce medical complications in cases of foreign body ingestions.

[Simultaneous implantation of epithesis anchors and Bonebridge to treat severe ear malformations]

OBJECTIVE

 Surgical treatment with bone conduction hearing implants and epitheses for ear malformations offer the right combination of hearing rehabilitation and cosmetic reconstruction. The surgical procedure is often performed in two-stage surgical steps. This project aimed to gain experience with a procedure in which the hearing implant and the epithesis anchors are inserted simultaneously.

MATERIAL AND METHODS

 Four ears of three patients (n_f = 1, n_m = 2) with severe ear malformations (type III, according to Weerda) received a Bonebridge and an epithesis anchor with three base posts in one operation each. Previously, the indication for the use of a bone conduction implant using the active middle ear implant (aMEI) score, according to Frenzel (2013), had been established.

RESULTS

 All patients scored 4 points each in the aMEI score, indicating an unfavorable prognosis for successful implantation of an active middle ear implant. The treatment with a Bonebridge and an epithesis anchor was performed without complications. Postoperatively, the initial audiological fitting and the application of the magnetic abutment were performed after 4 weeks. Audiometry showed a functional gain of up to 30 dB and an improved speech comprehension. The epithesis was shaped like the contralateral ear. After treatment, patients were satisfied with the audiological and cosmetic results.

CONCLUSIONS

 The simultaneous surgical procedure with a bone conduction hearing implant and epithesis anchor is a good option for the treatment of ear malformations. The aMEI-score was a helpful instrument for the indication. The procedure reduced the surgical risk and the time and effort required for treatment.

Evaluation of the Neurogenic Potential in the Rat Inferior Colliculus from Early Postnatal Days Until Adulthood

Neural stem cells (NSCs) have been recently identified in the inferior colliculus (IC). These cells are of particular interest, as no casual therapeutic options for impaired neural structures exist. This research project aims to evaluate the neurogenic potential in the rat IC from early postnatal days until adulthood. The IC of rats from postnatal day 6 up to 48 was examined by neurosphere assays and histological sections. In free-floating IC cell cultures, neurospheres formed from animals from early postnatal to adulthood. The amount of generated neurospheres decreased in older ages and increased with the number of cell line passages. Cells in the neurospheres and the histological sections stained positively with NSC markers (Doublecortin, Sox-2, Musashi-1, Nestin, and Atoh1). Dissociated single cells from the neurospheres differentiated and were stained positively for the neural lineage markers β-III-tubulin, glial fibrillary acidic protein, and myelin basic protein. In addition, NSC markers (Doublecortin, Sox-2, CDK5R1, and Ascl-1) were investigated by qRT-PCR. In conclusion, a neurogenic potential in the rat IC was detected and evaluated from early postnatal days until adulthood. The identification of NSCs in the rat IC and their age-specific characteristics contribute to a better understanding of the development and the plasticity of the auditory pathway and might be activated for therapeutic use.

Influence of cochlear parameters on the current practice in cochlear implantation : Development of a concept for personalized medicine

Since the introduction of cochlear implants into clinical routine, the interest in measuring cochlear parameters, particularly the cochlear duct length (CDL) has increased, since these can have an influence on the correct selection of the electrode. On the one hand, coverage of an optimal frequency band is relevant for a good audiological result, and on the other hand, cochlear trauma due to too deep insertion or displacement of the electrode must be avoided. Cochlear implants stimulate the spiral ganglion cells (SGC). The number of SGC and particularly their distribution can also have an influence on the function of a cochlear implant. In addition, the frequency assignment of each electrode contact can play a decisive role in the postoperative success, since the frequency distribution of the human cochlea with varying CDL shows substantial interindividual differences. The aim of this work is to provide an overview of the methods used to determine the cochlear parameters as well as of relevant studies on the CDL, the number and distribution of SGZ, and the frequency assignment of electrode contacts. Based on this, a concept for individualized cochlear implantation will be presented. In summary, this work should help to promote individualized medicine in the field of cochlear implants in the future, in order to overcome current limitations and optimize audiological outcomes.

Severe tracheobronchial harm due to lithium button battery aspiration: An in vitro study of the pathomechanism and injury pattern

BACKGROUND

Button battery incidents have become a rising medical issue in recent years, especially for infants. The increasing number of these cases can be explained by the expanding use of objects of everyday life and toys. As a result, button batteries in many households are ubiquitous in different states of charge. The extremely long shelf-life and the increasing energy densities of lithium button batteries boost the potential medical complications of accidental swallowing.

OBJECTIVE

The study aimed to analyze the pathophysiology of damage to tracheobronchial structures by button batteries aspiration over time.

METHODS

CR2032 and CR927 lithium button batteries (3.2/3.0 V) were exposed to porcine trachea preparations intraluminal at 37 °C in intervals up to 36 h. Measurements were made of the voltage curve, the discharge current, and the resulting pH values around the electrodes. The effects on tissue were examined using macroscopic time-lapse images and microscopic pictures of sections of the fixed specimens over time.

FINDINGS

The examinations showed a tissue electrolysis reaction directly after the beginning of battery exposure, which led to an immediate coagulation impairment of the respiratory epithelium. Over time, a strongly alkaline environment was established around the batteries. The resulting tissue colliquation caused profound tissue damage beyond the basal membrane of the mucosa, affecting the tracheobronchial cartilage after only 4 h of exposure time. After 12 h, there was significant necrosis of the annular ligaments of the trachea and the peribronchial pulmonary tissue. After completion of the experimental exposure time of 36 h, there was still a sufficient residual voltage on all button batteries of the experiments.

CONCLUSIONS

Besides accidental ingestion, the aspiration of button batteries is a life-threatening situation. The partial or complete acute airway obstruction in the trachea or the bronchi initially is the leading symptom, as with any foreign body aspiration. However, the results of the investigations show that even after a short exposure time, relevant tissue damage can be caused by the electrolysis reaction of the battery. After 12 h, a profound destruction of cartilage, connective tissue, and smooth muscles was observed in vitro, which may cause significant consequential damage in vivo. These findings reveal the need for rapid diagnosis and immediate foreign body removal after any battery ingestion. Moreover, the results show how relevant prevention of these accidents is, and that future safety modifications of these types of battery by the manufacturers would be appropriate.

Spatio-temporal distribution of tubulin-binding cofactors and posttranslational modifications of tubulin in the cochlea of mice

The five tubulin-binding cofactors (TBC) are involved in tubulin synthesis and the formation of microtubules. Their importance is highlighted by various diseases and syndromes caused by dysfunction or mutation of these proteins. Posttranslational modifications (PTMs) of tubulin promote different characteristics, including stability-creating subpopulations of tubulin. Cell- and time-specific distribution of PTMs has only been investigated in the organ of Corti in gerbils. The aim of the presented study was to investigate the cell type-specific and time-specific expression patterns of TBC proteins and PTMs for the first time in murine cochleae over several developmental stages. For this, murine cochleae were investigated at the postnatal (P) age P1, P7 and P14 by immunofluorescence analysis. The investigations revealed several profound interspecies differences in the distribution of PTMs between gerbil and mouse. Furthermore, this is the first study to describe the spatio-temporal distribution of TBCs in any tissue ever showing a volatile pattern of expression. The expression analysis of TBC proteins and PTMs of tubulin reveals that these proteins play a role in the physiological development of the cochlea and might be essential for hearing.

Inhibition of PKC β by Ruboxistaurin Does Not Enhance the Acute Blood Pressure Response to Nitroglycerin

Ruboxistaurin is a selective protein kinase C beta inhibitor undergoing clinical investigation for treatment of diabetic microvascular complications. This study assessed a possible blood pressure (BP) interaction between ruboxistaurin and the exogenous nitric oxide donor, glyceryl trinitrate (GTN). Subjects (N=22) with chronic stable angina received placebo or ruboxistaurin 96 mg/day orally to steady state in a crossover design. Graded GTN (0, 5, 10, 20, 40, 80, and 120 microg/min) or 5% dextrose solution was then infused intravenously and BP was measured following each dose. Ruboxistaurin did not alter the slope of change in standing systolic BP (DeltasSBP/1n[GTN dose]) curve (P=0.272 analysis of covariance) or affect the DeltasSBP at the estimated GTN dose producing a 10-mm Hg reduction in sSBP from baseline on placebo (mean difference -0.9 mm Hg; 95% confidence of interval, -3.3-1.5). In conclusion, ruboxistaurin does not potentiate the acute BP-lowering effects of GTN.

Transient enlargement of an intracranial aneurysm during pregnancy: case report

BACKGROUND

The association of intracranial aneurysm and pregnancy is uncommon. Hemodynamic stress plays an important role in the growth of aneurysms.

METHODS

The authors report the case of an enlarging cavernous carotid aneurysm in a pregnant 15-year-old young woman.

RESULTS

The aneurysm was initially diagnosed prior to the patient's pregnancy by both cross-sectional imaging and cerebral angiography. Further imaging evaluation was required during pregnancy, which demonstrated significant enlargement of the aneurysm. Following delivery, the lesion decreased in size.

CONCLUSIONS

We review potential factors associated with pregnancy that may increase hemodynamic stress and influence aneurysm growth. Additionally, the management of pregnancy-related intracranial aneurysms is discussed.

The renin angiotensin aldosterone system and frusemide response in congestive heart failure

1. To test the hypothesis that basal renin angiotensin aldosterone system (RAAS) activity impairs the acute natriuretic response to frusemide in patients with mild or moderate congestive heart failure (CHF), we studied eight adult volunteers with preserved renal function, stable New York Heart Association Class II or III CHF, and echocardiographic evidence of left ventricular dysfunction due to myocardial infarction, hypertension, or both causes. 2. All patients received three dosing regimens administered in random order: (a) intravenous frusemide: 40 mg bolus then 40 mg h-1 for 3 h, (b) captopril: two 12.5 mg oral doses separated by 2 h, (c) combined dosing: the first captopril dose preceded the frusemide bolus by 30 min. Sodium balance on an 80 mmol day-1 sodium diet was documented prior to each dosing regimen. Sodium excretion was quantitated in urine collected at intervals until 3.5 h after initiating drug administration. During this time, urine output was replaced intravenously with an equivalent volume of 0.45% saline. 3. Captopril significantly lowered plasma angiotensin converting enzyme (ACE) activity and plasma aldosterone concentration, and raised inulin clearance. The drug had essentially no effect on the time course of magnitude of frusemide's natriuretic effect. Maximal fractional sodium excretion during frusemide infused by itself and in combination with captopril was 24.7 +/- 1.9% vs 28.2 +/- 3.8%, respectively (difference 3.5%; 95% CI, -4.0 to 11.0%; P > 0.05). Cumulative sodium excretion ending at 3.5 h was 429 +/- 53 mmol when frusemide was given alone and 455 +/- 69 mmol when captopril was added (difference, 26 mmol; CI, -121 to 174 mmol; P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Medical complications of head injury

There are many common and significant medical complications of head injury. These include (1) cardiovascular problems such as hyperdynamic state, myocardial injury, and dysrhythmias; (2) respiratory changes such as neurogenic pulmonary edema, hypoxia, abnormal ventilatory patterns, pulmonary infections, and pulmonary emboli secondary to deep vein thrombosis; (3) consumption coagulopathy; (4) water and electrolyte derangements--hypo- and hypernatremia; (5) hypothalamic/pituitary dysfunction--syndrome of inappropriate secretion of antidiuretic hormone and diabetes insipidus; (6) increased general metabolism with loss of immunocompetence, respiratory compromise, and complications of decreased activity; (7) gastrointestinal difficulties, particularly stress gastritis; and (8) infectious problems including those related to contamination from open wounds and foreign bodies such as monitors.

Reduction of experimental neuroma formation with ricin

Twenty rat sciatic nerves were bilaterally transected, one as control, and one intraneurally injected with ricin. At 11 weeks, all controls demonstrated large neuromas. Ten injected nerves had no neuroma or a significantly smaller one, while the other 10 had neuroma formation similar to controls. No effect on distant dorsal root ganglia or spinal cord was seen. Thirteen additional rats underwent nerve injection with I125-labeled ricin. At one week, most radioactivity was localized to sciatic nerve, surrounding muscle, and thyroid, with trace amounts in dorsal root ganglia and spinal cord. Intraneural ricin can inhibit neuroma formation in transected nerve, but results in unpredictable uptake of ricin by nerve and excess spillage into surrounding tissues.

Prevalence of Paragonimus uterobilateralis infection in children in a Liberian village

Stool and sputum samples from 127 children in an endemic paragonimiasis area in Liberia, West Africa, were examined for the presence of lung fluke eggs. Samples from nine children (7%) were positive. The eggs were identified as those of Paragonimus uterobilateralis.

Morphology of the lung fluke Paragonimus uterobilateralis occurring in Gabon, West Africa

The morphology of two adult lung flukes and eggs obtained from an experimentally infected cat in Gabon corresponded in almost all details with the type material of Paragonimus uterobilateralis. The taxonomic differences between these lung flukes and the type material of P. africanus are summarized. The zoogeography of West African Paragonimus species is discussed.

Serum antibody levels in human paragonimiasis before and after therapy with praziquantel

Enzyme immunoassays (ELISA) and indirect haemagglutination (IHA) were used to determine IgG and IgE serum antibody levels in 43 patients from Ecuador before and after therapy with praziquantel. ELISA indicated infection more sensitively than IHA. The tendency of increasing antibody levels between the first and second month after therapy was more distinct when measured by IHA, whereas the decreases of antibody levels between the third and sixth month after treatment was more distinct when measured by ELISA. The IgG ELISA for detecting long persisting antibody was more sensitive than IHA.

[Paragonimus uterobilateralis as the cause of 3 cases of human paragonimiasis in Gabon]

During 1981, three cases of pulmonary paragonimiasis were diagnosed and successfully treated at the Albert Schweitzer Hospital, Lambarene, Gabon. Circumstances prevented our receiving eggs for identification of the lung fluke species involved. The history revealed that all the patients originated from the same small village Mitoné, some 10 km north of Lambarene. Extensive testing in the region failed to reveal further cases. Our efforts, therefore, were concentrated on the study of the intermediate crustacean hosts responsible for the human infections. We examined 90 fresh-water crabs of the species Sudanonautes aubryi and S. africanus collected from small creeks located close to the village of the patients. 14 per cent of the former species and 8 per cent of the latter contained freely moving, non-encysted metacercariae resembling those of Paragonimus uterobilateralis. A domestic cat was subsequently infected with these metacercariae. During autopsy of the cat some 260 days later, 2 adult lung flukes were recovered and clearly identified as P. uterobilateralis, confirming the diagnosis on the larval metacercariae. These findings support the surmise that the human cases of paragonimiasis in the same area could be attributed to an infection with P. uterobilateralis.

Human paragonimiasis caused by Paragonimus uterobilateralis in Liberia and Guinea, West Africa

In the children from Liberia and one woman from Guinea an infection with the lung fluke Paragonimus uterobilateralis was diagnosed, being the first cases of human paragonimiasis recorded in these two West African countries. Species determination was based on measurements and morphological structure of the parasite ova isolated from sputum and stool of the patients, and supported by biological and epidemiological evidence of the occurrence of this parasite species in natural animal hosts and P. uterobilateralis--metacercariae in freshwater crab populations in various parts of Liberia.

What is Paragonimus rudis (Diesing, 1850)? Report on a field study in Mato Grosso, Brazil

Paragonimus rudis was found in the lungs of a giant otter Lutra (pteronura) brasiliensis by Natterer in 1828, who dissected the animal in the former capital Mato Grosso (=Vila Bela), Brazil. The flukes were described by Diesing in 1850, and redescribed by Braun in 1901. Both descriptions do not allow to identify the species. Therefore, P. rudis must be regarded a "nomen nudum". Because its rediscovery is desirable with regard to historical reasons and nomenclatoric questions, a field study was performed in Mato Grosso in 1980. Of 354 freshwater crabs from 24 localities collected and examined for parasitic infections, about 25% were found to be infected with 7kinds of trematode larvae, which differed distincly from Paragonimus-metacercariae. The question, whether P. rudis or other lung fluke species do not seem to occur or cannot be found any longer in the area investigated by us, is discussed.

[Species characterization of the lung fluke Paragonimus ecuadoriensis by isoenzyme -electrophoresis (author's transl)]

Whole body lysates of 35 adult lung flukes (25 Paragonimus ecuadoriensis, 2 P. africanus, 8 P. uterobilateralis) were electrophorized on thin-layer starch gel. Specific staining was performed for the isoenzymes of the following three enzymes: alanine aminotransferase (ALAT), peptidase 1 (PEP) and malate dehydrogenase (ME) (decarboxylating) (NADP). Two enzymes showed polymorphism and proved to be useful for intra- and interspecific comparison. The individuals of P. ecuadoriensis showed homogeneity and differed remarkably from two other Paragonimus species examined as controls.

[A new lung fluke from the coastal range of ecuador: Paragonimus ecuadoriensis n.sp. (paragonimidae, trematoda) (author's transl)]

P. ecuadoriensis in the first lung fluke described from Ecuador. The description is based on 10 adult flukes from a natural infected Coati (Nasua nasua), 23 adults from 2 experimentally infected cats, and 200 metacercariae from the second intermediate host, the freshwater crab Hypolobocera aequatorialis. The new species is characterized by the following features: mouth succer larger than acetabulum or nearly of the same size; integument spines ("cuticular" spines) single; ovary with 5-6 short branches, which divide into more or less short broad lobes; testes larger than ovary with 5-6 simple or polymorphic lobes; eggs longish-ovoid, shell thin and uniform in thickness; surface undulated. Metacercariae not encysted. The adults of the new species are differentiated from probably related lung flukes P. peruvianus, P. mexicanus, and P. inca by the different morphology of ovary and testes, and by the size and form of the eggs. The metacercariae of P. ecuadoriensis are located not only in the hepatopancreas of the crab host - as it is in the case of P. peruvianus - but also and more frequently in the musculature. Paragonimus-eggs from sputum of two patients show partly the same characteristics as the eggs from animal hosts. One may therefore assume that P. ecuadoriensis is infecting humans in the investigated area.

[On the occurrence of human paragonimiasis in Ecuador (1972--76) (author's transl)]

During 1972 and 1976 316 cases of human paragonimiasis were stated in the following provinces of Ecuador: 19 cases in El Oro, 16 cases in Los Rios, 74 cases in Pichincha, and 206 cases in Manabi. 153 patients were males and 163 females. For localization of the probable origin of the infections the data of 192 patients could be utilized. The home villages and towns of these persons have been marked on a map. The majority of the patients were between 10 and 29 years of age. The youngest case was 4 years, the oldest 75 years old.

[Histopathological alterations in rhesus monkeys after experimental infections with African lung flukes (Paragonimus africanus and P. uterobilateralis) (author's transl)]

Histopathological observations in monkeys experimentally infected with African lung flukes are reported. The observations were made on 3 Rhesus monkeys, infected with Paragonimus africanus from West-Cameroon, and on 5 Rhesus monkeys, infected with P. uterobilateralis from Eastern Nigeria. For comparison, the lung of a naturally infected Drill (Mandrillus leucophaeus) was included in the study. The following lesions were found: formation of parasite cavernae, intense infiltration of the cavern wall with plasma cells; formation of egg granulomata in the lung tissue with intense plasma cell infiltration; peribronchial and perivascular cellular infiltration, concomitant and consistent pleuritis; reactive cellular hyperplasia of hilar lymph nodes and of spleen. Evidently, in the stages of infection examined so far, the immune response of the host is mainly of the humoral type. Experimental Paragonimus infections in monkeys may serve as a model in studies on human paragonimiasis in Eastern Nigeria and West-Cameroon. Likewise, they may serve in studies on granulomatous inflammation.

[On the distribution of the lung flukes, Paragonimus africanus and P. uterobilateralis, in the South West Province of Cameroon and in Eastern Nigeria as determined by examination of the intermediate crab hosts for infection with metacercariae (author's transl)]

During 1973-75 the distribution of the lung flukes, Paragonimus africanus and P. uterobilateralis, was studied in South West-Cameroon and in Eastern Nigeria, on the basis of parasitological examinations of the intermediate crab hosts Sudanonautes africanus, S. pelii, and S. aubryi, belonging to the family Potamonidae. 1000 freashwater crabs from 80 localities were examined for prevalence and intensity of infection with Paragonimus methacercariae. In Cameroon S. pelii was found to be a new intermediate host for P. uterobilateralis, and S. aubryi a new host for P. africanus. The morphology, behavior, and habitats of the crabs are summarized. In Eastern Nigeria only metacercariae of P. uterobilateralis were found. The main endemic area was located in the basin of the upper Imo River. Outside this area infected crabs were found only in and around Arochukwu, in the lower tributaries of the Cross River. This distribution differs from that given by Nwokolo (1974), which was based on the origin of clinical cases. These differences are discussed. In South West-Cameroon both Paragonimus species were found. The highest prevalence and intensity of metacercariae of P. africanus was seen in certain tributaries of the Mungo River in the area of Lower Bakossi. Proceeding northwards towards Mamfe, infections with P. africanus decreased steadily, whereas infections with P. uterobilateralis increased. On the upper reaches of the Cross River from the region around Mamfe and extending as far as the Nigerian fronter at Ekok, the crabs were infected exclusively with P. uterobilateralis. The unexplored mildle reaches of the Cross River may form a bridge between the endemic areas of this lung fluke in Nigeria and Cameroon.

A primate, Mandrillus leucophaeus, as natural host of the African lung flukeParagonimus africanus in West-Cameroon

Paragonimus africanus was recovered from a free-living drill (Mandrillus leucophaeus) in Cameroon. This is the first record on the natural infection of a non-human primate with lung flukes in Africa.