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Biomedical subjects

E Emmerich

Publications and source records attributed to E Emmerich.

At least 19 recordsLinked to original sources
PubMed2004

Is there a close relationship between changes in amplitudes of distortion product otoacoustic emissions and hair cell damage after exposure to realistic industrial noise in guinea pigs?

In long-term experiments in awake guinea pigs (n = 12), distortion product otoacoustic emissions (DPOAEs) at various frequencies were measured repeatedly over 6-8 months. About 9 weeks after the first measurement, the animals were exposed to industrial noise (car industry, maximal intensity about 110 dB SPL) for 2 h. The amplitudes of DPOAE were measured prior to noise exposure and 10 min, 70 min, 1 day and 2 days after the noise exposure and then once every week. Three to four months after noise exposure, the animals were killed, and the cochleae were prepared for scanning electron microscopy. The row of inner hair cells (IHCs) was complete in all animals, while the rows of outer hair cells (OHCs) showed a considerable hair cell loss in some of the animals without a correlation to the change in amplitudes of DPOAE. However, a closer relationship between the decline of amplitudes of DPOAE and the number of missing and changed OHCs (fused stereocilia bundles, missing tip links) could be established. The number of lost OHC does not reflect the decline in DPOAE in all cases. This discrepancy must be considered when the degree of hearing loss needs to be established from changed DPOAE.

Animals↗
PubMed2003

Wicking assays for the rapid detection of West Nile and St. Louis encephalitis viral antigens in mosquitoes (Diptera: Culicidae).

The recent outbreaks of West Nile (WN) encephalitis and St. Louis encephalitis (SLE) in the United States have highlighted the need for rapid and specific methods of detecting arboviral antigens in mosquitoes. We evaluated rapid, field-usable assays for detecting and differentiating WN and SLE viruses in mosquito pools, based on a patent-pending, immunochromatographic technology (VecTest) formatted on a dipstick. The device provides results in less than 20 min and can be used in laboratories with adequate containment facilities. In laboratory assessments, both the SLE and WN virus tests demonstrated sensitivity comparable with that of an antigen capture ELISA, but less than can be achieved with Vero cell plaque or reverse-transcriptase polymerase chain reaction assays. There was no evidence of cross-reaction when tested with high concentrations of heterologous flavivirus antigens or with Eastern equine encephalitis or Western equine encephalitis viruses. Both the WN and SLE dipstick tests delivered a clear positive result with a single positive specimen in a pool of 50 mosquitoes. This virus assay technology reduces the time required to obtain test results and will allow rapid medical threat assessment and effective targeting of vector control measures.

Animals↗
PubMed2001

Dipsticks for rapid detection of plasmodium in vectoring anopheles mosquitoes.

Malaria remains the most serious vector-borne disease, affecting some 300-500 million people annually, transmitted by many species of Anopheles mosquitoes (Diptera: Culicidae). Monoclonal antibodies developed against specific circumsporozoite (CS) proteins of the main malaria parasites Plasmodium falciparum and P. vivax have been used previously for enzyme-linked immunosorbent assays (ELISA), widely employed for detection of malaria sporozoites in vector Anopheles for local risk assessment, epidemiological studies and targeting vector control. However, ELISA procedures are relatively slow and impractical for field use. To circumvent this, we developed rapid wicking assays that identify the presence or absence of specific peptide epitopes of CS protein of the most important P. falciparum and two strains (variants 210 and 247) of the more widespread P. vivax. The resulting assay is a rapid, one-step procedure using a 'dipstick' wicking test strip. In laboratory assessment, dipsticks identified 1 ng/ mL of any of these three CS protein antigens, with sensitivity nearly equal to the CS standard ELISA. We have developed and are evaluating a combined panel assay that will be both qualitative and quantitative. This quick and easy dipstick test (VecTest Malaria) offers practical advantages for field workers needing to make rapid surveys of malaria vectors.

Animals↗
PubMed2000

The effect of impulse noise exposure on distortion product otoacoustic emissions in the awake guinea pig.

Distortion product otoacoustic emissions (DPOAE) are a sensitive detector of outer hair cell (OHC) function and were monitored in awake guinea pigs before and after impulse noise damaging the cochlea (peak intensity 153 dB SPL, rise time < 0.1 ms). Animals had stable DPOAE levels before noise exposure. In the first hours after noise exposure DPOAE levels were reduced significantly. Three different patterns of recovery of DPOAE were seen in the post-exposure period:restitution exceeding controls, partial recovery and no recovery. In general, DPOAE levels declined and types of recovery closely corresponded to changes in amplitudes of cochlear microphonics after noise exposure. These data suggest that the monitoring of DPOAE is a suitable method for diagnosing impaired OHC function.

Animals↗
PubMed2000

Effects of industrial noise exposure on distortion product otoacoustic emissions (DPOAEs) and hair cell loss of the cochlea--long term experiments in awake guinea pigs.

Distortion product otoacoustic emissions (DPOAEs), a sensitive detector of outer hair cell (OHC) function, cochlear microphonics (CM), and hair cell loss have been monitored in 12 awake guinea pigs before and after 2 h exposure to specific, played-back industrial noise (105 dB SPL maximal intensity). All animals had stable DPOAE levels before noise exposure. In the first hours after noise exposure DPOAE levels were reduced significantly. In about 70% a partial recovery of the DPOAEs was found within 4 months after noise exposure. In 16% of the investigated ears no recovery of DPOAEs was observed. However, in a few ears increased DPOAEs were observed after noise exposure. Exposure to industrial noise caused both morphological changes in the middle turns of the cochlea and electrophysiological changes in the middle frequency range. A close correlation existed between reduced DPOAE levels, loss in CM potentials, and area of damaged or lost OHCs, but not with the numbers of damaged or lost OHCs in the cochlea. It can be concluded that continuous industrial noise causes a damage to OHCs which differs form the damage caused by impulse noise.

Animals↗
PubMed2000

[Scanning electron microscopic findings concerning the formation of the organ of Corti near the helicotrema in guinea pigs].

We report on findings in guinea pigs with objectively tested normal hearing ability. At the apical end of the Corti organ only in the inner row of hair cells the stereociliae are detectable by scanning electron microscopy. Here the row is interrupted several times. Near the helicotrema we find first the inner row of the outer hair cells, then the middle row and finally the outer row. At the beginning of the D-turn their arrangement is disordered. Normally, at the basal end of the D-turn all rows of inner and outer hair cells show their typical formation. This finding should be taken into consideration when making a cochleogram for proving of experimental noise damages.

Animals↗
PubMed1998

Hemispheric differences in frequency dependent dipole orientation of the human auditory evoked field component N100m.

Auditory evoked fields (AEF) of 19 healthy male subjects were recorded bilaterally with a Philips 31 -channel biomagnetometer, using two conditions of stimulation (1000 vs. 5000 Hz tones). The N100m latency was characterized by a single moving dipole for each condition and hemisphere using a boundary element model (BEM) as volume conductor. While the right hemispheric dipole orientations and locations did not change with respect to condition, the left hemispheric dipoles differed significantly between the 1000 and 5000 Hz tones, especially in dipole orientation. The left hemispheric dipoles were orientated on average 10.8 degrees more vertically for the 5000 Hz condition. This result points to interhemispheric differences on the level of sensory processing.

Acoustic Stimulation↗
PubMed1990

Auditory evoked responses in awake rabbits after exposure to high intensity noise impulses.

Impulse noise effects were tested in chronic experiments on 8 awake rabbits. Alterations of cochlear potentials and evoked responses from the inferior collinulus and the medial geniculate body were studied. The rabbits were subsequently exposed to 10 noise impulses of 144 dB SPL, then (after recovery) to 10 impulses of 153 and 164 dB SPL. After exposure the amplitudes of all potentials were reduced. Time of restitution depended on the intensity of the noise, the restitution failed after exposure to 164 dB SPL impulses. Time lapses of the amplitude-reduction and restitution process were comparable for both structures of the auditory pathway. The peak latencies were prolonged significantly in only two of the rabbits after this impulse intensity. Impulses of 164 dB SPL were followed by irreversible changes of all evoked responses.

Acoustic Stimulation↗
PubMed1986

[Action of a dietary Mg2+ deficiency and overload in the male rat: measurement of certain parameters of testicular and spermatozoan activity].

The specific activities of several enzymes were investigated as possible markers of the Mg2+ impact on testicular and spermatozoa glucidic metabolism: no modification was noticed. However, as a reflection of hormonal metabolism, 17 beta-OH steroid-deshydrogenase activity, AMPc and testosterone levels were measured in the testes and showed significant variations.

Animals↗
PubMed1980

[ERG changes caused by stimulation of the reticular formation of the mesencephalon].

During stimulation of the Formatio reticularis mesencephali by different intensities in awake rabbits three types of the ERG were observed. During and 20 min after subthreshold stimulation (no alteration in the hippocampal EEG) the b-wave of the ERG was enhanced. However, the b-wave amplitude was diminished during stimulation and enhanced 20 min after stimulus application when the stimulus intensity evoked a hippocampal theta-rhythm of 5-7 waves/s. During and 20 min after RFm stimulation with the highest stimulus intensity which evoked a hippocampal theta-rhythm of 7-8 waves/s the b-wave was diminished.

Animals↗
PubMed1978

[Changes of electroretinograms following hippocampus stimulation].

In chronical experiments the ERG of 5 rabbits were recorded before and after stimulation of the hippocampus. Stimulation of the hippocampus causing short generalized afterdischarge produced changes of the b-wave amplitude. Immediately after the stimulation the b-wave amplitude was larger than the amplitude in the control series. If the intensity of hippocampal stimulation was lower (no generalized afterdischarges) changes of b-wave amplitude were also produced, though being less pronounced. The results suggest that retinal processes are influenced by hippocampus.

Animals↗
PubMed1975

[The effect of pregnant mare's serum on the level of K+ ions in the immature rat ovary].

Pregnant Mare Serum Gonadotrophin enhanced potassium level in immature rat ovaries in comparison with controls, three hours after intravenous injection. In vivo 42K uptake was also 36% higher (p less than or equal to 0,01) in PMSG primed rat ovaries. This response was specific to the ovary. Experiments are carried out to determine correlation between K+ level and macromolecule biosynthesis.

Animals↗