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Biomedical subjects

H Scherer

Publications and source records attributed to H Scherer.

At least 37 records · Page 2Linked to original sources
PubMed2004

CO2 laser stapedotomy with the "one-shot" technique--clinical results.

OBJECTIVE: To further optimize the surgical technique with the CO 2 laser in stapes surgery a scanner system was used to obtain a footplate perforation of 0.5 to 0.6 mm with only 1 laser application ("one-shot" stapedotomy). STUDY DESIGN: 188 patients with otosclerosis were submitted to a primary CO 2 laser stapedotomy with the SurgiTouch scanner. This study surveys the surgical technique and clinical results. RESULTS: An adequately large perforation diameter could be achieved with a single shot in 68% of the patients treated with the SurgiTouch scanner. In 11% of the patients, a second laser application at the same site was necessary. In 21% of the patients, the perforation had to be enlarged by several slightly overlapping laser applications without scanner. The clinical data of this study clearly documents that there is no evidence of laser depending inner ear affections. CONCLUSION: The CO 2 laser combined with modern scanner systems is well suited for application in stapes surgery.

Adult↗
PubMed2003

Oesophageal squamous cell neoplasia in head and neck cancer patients: upregulation of COX-2 during carcinogenesis.

Patients with (previous) head and neck cancer (HNC) are at high risk for developing second squamous cell cancer of the oesophagus. The role of cyclooxygenase-2 (COX-2) in oesophageal squamous carcinogenesis has not yet been investigated in this high-risk group. Therefore, this study examined COX-2 mRNA and protein expression in oesophageal biopsies and resected tissues of 44 HNC patients. The evaluation covered 55 oesophageal tissue samples (18 invasive oesophageal squamous cell cancers, four high- and eight low-grade dysplasias, 25 normal squamous epithelia) from the 44 patients. mRNA levels of COX-2 were measured by real-time PCR using a LightCycler. COX-2 protein expression was studied immunohistochemically and graded by a staining score. COX-2 mRNA was detected in all samples, and its levels correlated positively with the immunohistochemical staining score (P<0.05). COX-2 expression was upregulated during oesophageal squamous carcinogenesis in HNC patients, that is COX-2 expression increased significantly from normal oesophageal squamous epithelium to low- and high-grade dysplasia and finally to invasive squamous cell cancer (P<0.001). Our findings suggest that COX-2 upregulation contributes to oesophageal squamous carcinogenesis in HNC patients. Prospective studies are needed to evaluate the chemopreventive potential of COX-2 inhibitors in this high-risk group.

Base Sequence↗
PubMed2003

[Therapeutic and histological features of basaloid squamous cell carcinoma].

BACKGROUND AND OBJECTIVE: Basaloid squamous cell carcinoma s a rare, highly malignant carcinoma variant typically situated in the tongue base, supraglottis and pyriform sinus. It is usually only diagnosed at a very advanced stage due to its tendency towards submucosal growth, deep infiltration and early local and distant metastases. PATIENTS/METHODS: The case described involves a 39-year-old man with the clinical and histopathological findings typical for this neoplasm. RESULTS: In contrast to simple squamous cell carcinomas, the basaloid variant with its very poor prognosis calls for therapeutic decisions that give particular consideration to quality of life. It should be stressed that highly invasive surgery is justified only in exceptional cases because of the high local recurrence rate and early distant metastases. CONCLUSIONS: The case presented shows that radio- and chemotherapeutic approaches are just as important as surgery.

Adult↗
PubMed2002

Screening for oesophageal neoplasia in patients with head and neck cancer.

Due to advanced disease at the time of diagnosis the prognosis of oesophageal cancer is generally poor. As mass screening for oesophageal cancer is neither feasible nor reasonable, high-risk groups should be identified and surveilled. The aim of this study was to define the risk of oesophageal cancer in patients with (previous) head and neck cancer. A total of 148 patients with (previous) head and neck cancer were prospectively screened for oesophageal cancer by video-oesophagoscopy and random oesophageal biopsies. Even in a macroscopically normal looking oesophagus, four biopsy specimens were taken every 3 cm throughout the entire length of the squamous oesophagus. Low- or high-grade squamous cell dysplasia was detected histologically in 10 of the 148 patients (6.8%). All but one dysplasias were diagnosed synchronously with the head and neck cancers. In addition, oesophageal squamous cell carcinoma was diagnosed in 11 of the 148 patients (7.4%). Most invasive cancers (63.6%) occurred metachronously. The risk of squamous cell neoplasia of the oesophagus is high in patients with (previous) head and neck cancer. Surveillance is recommended in this high-risk group.

Aged↗
PubMed2002

[Laser tonsillectomy in tonsillar hyperplasia of early childhood].

Tonsillotomy, the partial resection of hyperplastic tonsils, is generally rejected in Germany as a treatment option for obstructions of the isthmus faucium in early childhood. We think this approach merits consideration. The favorable results obtained with tonsillotomy in the University Hospital Benjamin Franklin (n = 637), a private clinic, and an ENT practice with surgical facilities (n = 189) showed that there is no justification for adhering to literature reports of severe late complications with scarred tonsillar crypts and peritonsillar abscesses. No patient has developed any of these complications thus far. Following tonsillotomy, preoperative complaints (snoring, respiratory obstruction, dysphagia, and failure to grow) decreased considerably. Thus, tonsillotomy proved to be a suitable modality for treating tonsillar hyperplasia in early childhood. The prerequisite for long-term success is strict limitation of this intervention to the diagnosis of tonsillar hyperplasia.

Airway Obstruction↗
PubMed2001

The strong connection between sensory and cognitive performance in old age: not due to sensory acuity reductions operating during cognitive assessment.

Cognitive aging research has documented a strong increase in the covariation between sensory and cognitive functioning with advancing age. In part, this finding may reflect sensory acuity reductions operating during cognitive assessment. To examine this possibility, the authors administered cognitive tasks used in prior studies (e.g., Lindenberger & Baltes, 1994) to middle-aged adults under age-simulation conditions of reduced visual acuity, auditory acuity, or both. Visual acuity was lowered through partial occlusion filters, and auditory acuity through headphone-shaped noise protectors. Acuity manipulations reduced visual acuity and auditory acuity in the speech range to values reaching or approximating old-age acuity levels, respectively, but did not lower cognitive performance relative to control conditions. Results speak against assessment-related sensory acuity accounts of the age-related increase in the connection between sensory and cognitive functioning and underscore the need to explore alternative explanations, including a focus on general aspects of brain aging.

Adult↗
PubMed2001

Measuring unilateral otolith function via the otolith-ocular response and the subjective visual vertical.

In the present study, attention is directed to the unilateral response of the otolith system to static and dynamic tilt, as reflected by subjective estimation of the visual vertical (oculogravic perception). Measurements were performed with a variable radius rotary chair, which permits controlled modulation of the centripetal, or radial, acceleration. By limiting the radius, i.e. eccentric displacement of the head by 3.5 cm during constant-velocity rotation about the earth-vertical axis, adequate unilateral stimulation of the otolith organ--predominantly the utricle--is generated, without involving the semicircular canals. This paradigm has been employed to measure the unilateral utriculo-ocular response. In contrast to the otolith-ocular response (OOR), the subjective visual vertical (SVV) reflects the processing of otolithic information in the higher brain centres (thalamus, vestibular cortex). Exploitation of these two complementary approaches provides useful information for both experimental and clinical scientists. The findings also reveal that centripetal acceleratory stimulation during constant angular velocity with the subject centred on axis is sufficient to localize peripheral otolith dysfunction by means of SVV estimation. This represents a novel test of otolith function that can be easily integrated into routine clinical testing.

Acceleration↗
PubMed2001

Electron microscopic studies of ion- and H2O-transporting epithelial cells in the horizontal ampulla of the pigeon.

Earlier morphological studies of the epithelial structure in the semicircular canals of mammals have focused on the sensory cells of the crista ampullaris. This report draws attention to the fact that there exist at least seven further cell types in the horizontal ampulla walls of pigeon with various functions; the role of ion- and H2O-transporting epithelial cells is dealt with here in detail. While the dark cells appear to play a decisive role in the regulation of ionic composition, the cells in the planum semilunatum may transport H2O and assist in the regulation of endolymph volume. In addition, protein-secreting structures are located in the apical region of the cells of the planum semilunatum. The question whether the proteins are dispersed in the endolymph or contribute to cupula formation remains unclear. The morphology and possible functions of these two cell types are discussed on the basis of electron microscopic results.

Animals↗
PubMed2001

Passage of dextran magnetite nanoparticles through the subcupular space of the pigeon.

We examined the permeability of the subcupular space for endolymph flow in the pigeon. A new technique was developed in which nanoparticles consisting of dextran magnetite were attracted by use of a magnet, instead of injecting a dye solution. The method was revealed to prevent an excess pressure application by the injection of dye solution. The Berlin blue color resulting from the dextran magnetite nanoparticles was found mainly within the subcupular space contacting with the sensory hairs. Further formation of the Berlin blue was found within the sensory cells. The result supports the idea that the fluid passes through the subcupular space.

Animals↗
PubMed2001

Cupular response and functional anatomy to pressure application in the pigeon.

In this study, horizontal semicircular canal of the pigeon was inserted with a microfill, 164 micrometers in outer diameter, to gauge the pressure change in the canal and to clarify two things. One is whether the endolymph passes through the crista ampullaris or not. The other is as to the space where the endolymph passes through in the crista ampullaris if the endolymph goes through the crista. The pressure applications were performed by using Evans blue solution and as a result three pressure groups, i.e., 1) high, 2) moderate and 3) low were discriminated. Our results suggest that the endolymphatic fluid passes through the subcupular space or the top of the crista ampullaris when the pressure is enough small like the head rotates in daily life. Accordingly we present a new hypothesis as to the functional anatomy of the cupula in contrast to current hypotheses e.g. drum membrane or revolving door.

Animals↗
PubMed2001

Motion sickness and otolith asymmetry.

There is a highly scattered inter-individual susceptibility in man to motion sickness. It is discussed whether different masses of otoconias between right and left sides are responsible for a high susceptibility. In order to proof this theory, we measured the otoliths of fish (salmons, trouts, Xiphophorus Helleri; Sumatra barbes) and found big differences in the utricular stones up to 140%. The mass differences of the saccular stones were much smaller. In fish, showing abnormal swimming behavior during off-vertical axis rotation we found big mass differences compared to that of normal swimmers. This difference was only seen in the utricular and not in the saccular stones. We therefore assume, that a big mass difference is one of the factors to trigger motion sickness especially for the high susceptibility to it. The macula utriculi seem to be much more integrated in the vestibular sense than the macula sacculi.

Animals↗
PubMed2000

[Morphological studies of the form of the cupula in the semicircular canal ampulla].

BACKGROUND AND OBJECTIVE: The cupula in the ampulla of the semicircular canal, like the tectorial membrane in the cochlea, forms the essential link in transferring endolymph fluid movement stimuli to the hair cells. Clear understanding of physiological cupula movement only started evolving towards the end of the 1970s. Currently, the cupula is assumed to adhere firmly to the ampulla wall, with diaphragm-like displacement in the central section and at the base. PATIENTS/METHODS: In contrast to detailed functional descriptions, there have been very few investigations on cupula morphology. These have proved difficult due to the extremely hydrous structure, which inevitably results in shape distortion during fixation. This difficulty applies particularly to electron microscopy. RESULTS: The present morphological investigations were performed in artificial endolymph on fresh preparations in the salmon (Salmo salar). After staining and isolating the cupula from the ampulla, a precise morphological investigation was performed. A relatively uniform basic structure was observed, with considerable interindividual variability in cupula shape. CONCLUSIONS: Such variability suggests that impairment of cupular form can occur and could be associated with altered peripheral vestibular function.

Animals↗
PubMed2000

The three-dimensional vestibulo-ocular reflex during prolonged microgravity.

Single-case, longitudinal studies of the three-dimensional vestibulo-ocular response (VOR) were conducted with two spaceflight subjects over a 180-day mission. For reference, a control study was performed in the laboratory with 13 healthy volunteers. Horizontal, vertical and torsional VOR was measured during active yaw, pitch and roll oscillations of the head, performed during visual fixation of real and imaginary targets. The control group was tested in the head-upright position, and in the gravity-neutral, onside and supine positions. Binocular eye movements were recorded throughout using videooculography, yielding eye position in Fick co-ordinates. Eye velocity was calculated using quaternion algebra. Head angular velocities were measured by a head-mounted rate sensor. Eye/head velocity gain and phase were evaluated for the horizontal, vertical and torsional VOR. The inclination of Listing's plane was also calculated for each test session. Control group gain for horizontal and vertical VOR was distributed closely around unity during real-target fixation, and reduced by 30-50% during imaginary-target trials. Phase was near zero throughout. During head pitch in the onside position, vertical VOR gain did not change significantly. Analysis of up/down asymmetry indicated that vertical VOR gain for downward head movement was significantly higher than for upward head movement. Average torsional VOR gain with real-target fixation was significantly higher than with imaginary-target fixation. No difference in phase was found. In contrast to vertical VOR gain, torsional VOR gain was significantly lower in the gravity-neutral supine position. Spaceflight subjects showed no notable modification of horizontal or vertical VOR gain or phase during real-target fixation over the course of the mission. However, the up/down asymmetry of vertical VOR gain was inverted in microgravity. Torsional VOR gain was clearly reduced in microgravity, with some recovery in the later phase. After landing, there was a dip in gain during the first 24 h, with subsequent recovery to near baseline over the 13-day period tested. Listing's plane appeared to remain stable throughout the mission. The findings reflect various functions of the otolith responses. The reduced torsional VOR gain in microgravity is attributed to the absence of the gravity-dependent, dynamic stimulation to the otoliths (primarily utricles). On the other hand, the reversal of vertical VOR up/down gain asymmetry in microgravity is attributed to the off-loading of the constant 1-g bias (primarily to the saccules) on Earth. The observed increase in torsional VOR gain from the 1st to the 6th month in microgravity demonstrates the existence of longer-term adaptive processes than have previously been considered. Likely factors are the adaptive reweighting of neck-proprioceptive afferents and/or enhancement of efference copy.

Eye Movements↗