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Biomedical subjects

S Preyer

Publications and source records attributed to S Preyer.

16 recordsLinked to original sources
PubMed1995

Benign supraclavicular tumorous lymphangiectasia--a new disease?

We describe an isolated recurrent non-inflammatory tumorous swelling of the supraclavicular fossa in four premenopausal women. Ultrasonography, magnetic resonance imaging and computer tomography of the neck each suggested an inhomogeneous mass consistent with "lymphangioma." In each patient the clinical course and histopathologic findings suggested that the swellings were due to chronic localized lymph stasis with subsequent lymphangiectasia, possibly initiated by intermittent obstruction of the juncture of the thoracic or right lymph duct with the internal jugular vein. Enlargement may have been hormonally triggered by estrogens as each woman was taking oral contraceptive pills at the onset of the disease. To characterize this unique entity, we have termed the disorder benign supraclavicular tumorous lymphangiectasia.

Adult↗
PubMed1995

[Tinnitus models for use in tinnitus counselling therapy of chronic tinnitus patients].

Tinnitus models are an integral part of tinnitus counselling. In cases with compensated tinnitus, counselling represents the only therapeutic measure necessary. In contrast, patients with uncompensated tinnitus require further therapy in the form of medication, tinnitus-maskers or psychotherapy. Sound processing along the peripheral and central auditory pathways is achieved by functional loops that direct mechanical, electrical or chemical information to various points in the pathway. Minor damage to a loop can cause destabilization of this finely balanced system and can induce tinnitus. Current peripheral tinnitus models are reviewed and discussed with respect to in vitro data from isolated outer hair cells of the guinea pig cochlea. Audiological findings of a patient with central tinnitus after brainstem surgery are discussed in view of central tinnitus models. Specific models for common hearing disorders, such as tinnitus with normal hearing, noise trauma, sudden hearing loss, toxic cochlear lesions, presbyacusis, acoustic neurinoma and Menière's disease are presented for the ENT-surgeon involved with tinnitus-counselling.

Adult↗
PubMed1994

Frequency response of mature guinea-pig outer hair cells to stereociliary displacement.

Outer hair cells (OHC) were isolated from the apical two turns of the guinea-pig cochlea and their hair-bundle stimulated mechanically by a glass probe. In accordance with in vivo data (Dallos, 1985), the resting membrane potential was typically -64 mV (N = 200). The maximum amplitudes of the receptor potentials were between 0.4 and 5.2 mV peak-to-peak, with mean of 1.5 mV +/- 0.9 mV (N = 81). The sensitivity was 0.015 mV/nm or 2 mV/deg. The frequency response of the receptor potential followed a first order low-pass filter characteristic with a corner frequency of about 63 Hz. For frequencies up to at least 1.6 kHz, the frequency response of mechanoelectrical transduction was dominated by the electrical input impedance of the cell. The presence of a single time constant in the voltage response to stereociliary deflection implies that the frequency response of mechanoelectrical transduction far exceeds that of the electrical input impedance of the cell; its time constant must be faster than 100 microseconds. Under in vivo conditions, OHC should be capable of providing a sufficiently large receptor potential to supply enough energy for electromechanical feedback.

Acoustic Stimulation↗
PubMed1994

Electromotility of outer hair cells from the cochlea of the echolocating bat, Carollia perspicillata.

Isolated outer hair cells (OHCs) and explants ot the organ of Corti were obtained from the cochlea of the echolocating bat, Carollia perspicillata, whose hearing range extends up to about 100 kHz. The OHCs were about 10-30 microns long and produced resting potentials between -30 to -69 mV. During stimulation with a sinusoidal extracellular voltage field (voltage gradient of 2 mV/microns) cyclic length changes were observed in isolated OHCs. The displacements were most prominent at the level of the cell nucleus and the cuticular plate. In the organ of Corti explants, the extracellular electric field induced a radial movement of the cuticular plate which was observed using video subtraction and photodiode techniques. Maximum displacements of about 0.3-0.8 microns were elicited by stimulus frequencies below 100 Hz. The displacement amplitude decreased towards the noise level of about 10-30 nm for stimulus frequencies between 100-500 Hz, both in apical and basal explants. This compares well with data from the guinea pig, where OHC motility induced by extracellular electrical stimulation exhibits a low pass characteristic with a corner frequency below 1 kHz. The data indicate that fast OHC movements presumably are quite small at ultrasonic frequencies and it remains to be solved how they participate in amplifying and sharpening cochlear responses in vivo.

Animals↗
PubMed1994

[Microvascular tissue transplantation in plastic reconstruction of the external head-neck area].

Free tissue transfer is under certain circumstances an ideal reconstructive method for skin and soft tissue defects of the head and neck region. These are multilayer, large defects, recurrences after previous reconstructive methods, in cases of aesthetic disturbances due to local flaps, in difficult reconstructive areas due to chronic infection and radiotherapy and if local tissue is not available. From 1987 to 1993 we performed 30 reconstructions of the surface of the head and neck region with free flaps, mainly the forearm flap and the scapular flap. But also the latissimus dorsi flap and in one case the rectus abdominis flap were used. There was no flap failure. In only one case of a forearm flap we saw a delayed healing of the donor defect. There was no functional impairment of the donor defect. All cosmetical results were acceptable. Flaps from the trunk mainly showed considerable differences in colour and texture to the surrounding skin.

Adult↗
PubMed1993

[Mechanical stimulation of isolated outer hair cells as a test system. Inhibition of transduction by streptomycin treatment].

Deflection of the hair bundle of isolated outer hair cells from the guinea pig cochlea can induce a receptor potential. Outer hair cells from the third and fourth turns of the guinea pig cochlea were isolated according to the method described by Zenner et al. Cells were maintained in Hank's balanced salt solution at room temperature. The whole cell potential was measured by the patch-clamp technique with soda glass capillaries (resistance 3-5 M omega) filled with KCl-Ringer solution. After compensation for the junction potential the stable resting potential of 46 cells was -63 mV +/- 5 mV. The hair bundle was deflected sinusoidally, with amplitudes ranging from 6 degrees to a maximum of 31 degrees in the positive direction (i.e., in the direction of the longest stereocilium). The stimulus was a piezo-driven glass capillary with an opening diameter of 5 microns. This mechanical stimulation induced in 33% of all stimulated cells (n = 46) a receptor potential response of 2.1 +/- 1.4 mV (maximally 5.5 mV). Deflection of the hair bundle in the opposite direction led to no change in the membrane potential, i.e. the cells were not hyperpolarized (minimal resolution 0.5 mV). Since the resting potential of the cells was more positive than the potassium equilibrium potential under our experimental conditions, the receptor current was most likely mediated by an influx of Na+ ions into the cell. The receptor potential response could be completely and reversibly blocked by the addition of dihydro-streptomycin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[Polypoid pansinusitis in an unusual, extra-intestinal manifestation of Crohn disease].

A 17-year-old female patient with known Crohn's disease developed a polypoid pansinusitis and a peritonsillitis during an acute inflammatory phase of her disease. The symptoms observed in the paranasal sinuses and in the oropharynx disappeared after treatment with cortisone and antibiotics was started. The histological findings in the biopsy specimens taken from the affected regions as well as the course of the disease suggest the extraintestinal manifestation of Crohn's disease.

Adolescent↗
PubMed1992

[A short history of hearing research. IV: Physiology].

In 1863, Hensen concluded from measurements of the width of the basilar membrane that tones of high and low pitch were represented at the base and apex of the cochlea, respectively. According to his calculations on the tonotopic representation of sound stimuli in the cochlea Helmholtz proposed additional resonators that would transmit the amplified signal to the afferent nerve endings. He speculated that the pillar cells of the tunnel of Corti or strands of the basilar membrane might be these proposed resonators. The resonance theory was contradicted by Wien in 1905. However, further experiments by Held and Kleinknecht in 1927 and by Békésy in 1928 demonstrated that Helmholtz's ideas on the tonotopic dispersion of the vibration of the basilar membrane were correct. Békésy measured the vibration of the cochlear partition in human and animal cadavers and discovered the travelling-wave of the basilar membrane. At the turn of the century Ter Kuile noted that the vibration of the cochlear partition caused a deflection of the sensory hairs of the hair cells, the auditory receptor cells. Wever and Bray described in 1930 stimulus-evoked electrical currents near the cochlea with a wave form similar to that of the original sound stimulus. It was Adrian who later coined the term "cochlear microphonics" for this phenomenon. According to calculations of Gold (1948) and others active mechanical amplification would be required for such a sharp tuning in the cochlea. The first to measure action potentials of the afferent auditory nerve was Tasaki (1954).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Prospective study of the cardiovascular risk of patients with sudden deafness].

In this prospective case control study 135 patients with sudden hearing loss were compared with regard to their cardiovascular risk with 135 otologically healthy patients and 111 patients with coronary heart disease. The groups were matched according to age, sex and date of onset of disease. The risk factors investigated were: serum cholesterol, low-density lipoproteins, high-density lipoproteins, triglycerides, blood pressure, body weight, diabetes mellitus, positive family history of coronary heart disease and smoking habits. There was no significant difference between the patients with sudden hearing loss and otologically healthy patients. However, the difference between these two groups of patients and the patients with coronary heart disease was very pronounced. The groups of patients with a low frequency, high frequency or pantonal hearing loss did not differ with respect to the distribution of coronary risk factors. Furthermore, no statistical correlation was found between the degree of recovery of hearing function after sudden hearing loss and coronary risk factors.

Coronary Artery Bypass↗
PubMed1991

[A brief history of hearing research. III. Microscopic anatomy].

The present review provides merely a glimpse of the vast field of modern anatomy of the ear, which began with the introduction of the light microscope and histological techniques. Owing to the poor accessibility and small size of the inner ear, the investigation of its structure was highly dependent on the development of modern histological techniques, i.e. fixation, embedding, sectioning and staining of tissue, which took place in the 19th century. In 1824 Huschke discovered the papilla spiralis acoustica and in 1851 Corti described the structure of the sensory epithelium of the inner ear, and also detected the outer hair cells. A little later Deiters also found the inner hair cells, while Leydig discovered the stereocilia on the hair cells. In 1863 Hensen showed that the hair cells were provided with nerve endings, but it was Retzius who proved that the nerve fibres terminate at the basal end of the hair cells. He concluded from his studies that the hair cells are the actual receptors of the organ of hearing. Hensen, Retzius and Held provided morphometric data of the cochlea which are still largely valid today. In 1926 Held managed to isolate single hair cells. He also described two different types of nerve fibre in the cochlea. In 1926, Kolmer was the first to propose that apart from afferent nerve fibres there might also be an efferent innervation of the cochlea. In 1942 this was confirmed by Rasmussen. In animal experiments, he and others demonstrated the efferent nature of the olivo-cochlear bundle by dividing the nerve, which subsequently showed secondary descending degeneration.(ABSTRACT TRUNCATED AT 250 WORDS)

Anatomy↗
PubMed1987

[Antibiotics and blood coagulation--current references for the ENT physician].

A rare but important side effect of antibiotics is their inhibitory effect on haemostasis and blood coagulation. Modern antibiotics with a wide spectrum like cephalosporins of the 2nd and 3rd generation, as well as semisynthetic penicillins, can imitate warfarin in its effect on the blood clotting system. Other antibiotics can enhance the effect of warfarin derivatives when given simultaneously. The mechanism by which penicillin and its derivatives inhibit platelet aggregation is not yet clear. Other antibiotics can induce thrombo-cytopenia. Before antibiotic treatment is started the doctor should consider liver and kidney function, a possible malnutrition, interaction with other drugs (especially inhibitors of platelet aggregation and warfarin derivatives), and other diseases of the patient that also prolong bleeding time.

Anti-Bacterial Agents↗
PubMed1986

Immunoassay of bovine and human low-density-lipoprotein receptors using monoclonal antibodies.

Two methods are described for the assay of low-density-lipoprotein (LDL) receptor protein based on the binding of receptor to microtitre plate wells coated with a specific monoclonal antibody or with LDL, followed by detection with radioactive antibody that recognizes a different part of the molecule. The two-antibody procedure detected approx. 2 ng of pure bovine receptor at twice background, and there was a linear relationship on a double-logarithm plot between radioactive antibody bound and the amount of receptor added, up to at least 500 ng of receptor protein per well. The procedure using immobilized LDL was less sensitive and the binding of receptor was inhibited by low concentrations of NaCl, which restricted its usefulness for routine assay of tissue extracts. LDL receptor protein could be readily assayed using the two-antibody procedure in normal human skin fibroblast extracts prepared by bulk-elution from small columns of DEAE-cellulose followed by rapid desalting. No radioactive antibody bound with extracts of cells from a receptor-negative familial hypercholesterolaemic subject. The LDL receptor content of normal fibroblasts preincubated with lipoprotein-deficient serum was estimated, using bovine receptor as standard, to be approx. 60 ng of receptor protein/mg of cell protein.

Adrenal Cortex↗
PubMed1986

Influence of lysophosphatidylcholine on the C-apolipoprotein content of rat and human triglyceride-rich lipoproteins during triglyceride hydrolysis.

Remnants produced from rat chylomicrons in hepatectomized rats or from human chylomicrons by incubation in postheparin plasma contained much less C-apolipoproteins, but more lysophosphatidylcholine than the parent chylomicrons. A phospholipid-triglyceride emulsion absorbed C-apolipoproteins during incubation in serum, yet not in postheparin plasma, which led to lipid-hydrolysis and increased in lysophosphatidylcholine. The fraction d = 1.006-1.019 g/ml of human serum comprised more lysophosphatidylcholine and less C-apolipoproteins than the fraction d less than 1.006 g/ml. Injection of heparin induced hydrolysis with an increase in lysophosphatidylcholine and loss of C-apolipoproteins in both fractions. These inverse changes of lysophosphatidylcholine and C-apolipoproteins during lipid-hydrolysis suggest a causal relationship, which is strongly supported by the induction of loss of C-apolipoproteins from rat chylomicrons and human triglyceride-rich lipoproteins by addition of lysophosphatidylcholine in vitro. Apolipoprotein C-II was more affected than C-III. These results may elucidate a mechanism for the regulation of the termination of the triglyceride hydrolysis and the final hepatic uptake of remnants.

Animals↗