摘要:

This study, using mice, correlated serum osmotic pressure, experimentally elevated with an intravenous injection of glycerol of varying tonicity (1.3, 2.6 and 5.2 g glycerol/kg body weight) with endolymphatic sac (ES) response. The injection produced a rise in serum osmotic pressure that was measured after 15min (from 308 ± 12.9 mosm/kg b.w. to 320 ± 1.9, 353 ± 19.3, 427 ± 9.4 mosm/kg b.w., respectively). Normal levels were noted about 60 min after the injection. The ES was graphically displayed at 0 min, 1, 2 and 4 h using as a basis composite electron micrographs. The ES responded with signs of active secretion and degradation of macromolecular substances which appeared to be related to the rise in serum osmotic pressure. The study showed that the ES responds to glycerol injection with fine structural changes indicative of increased intra-epithelial synthesis of sugar/protein residues which are secreted and degraded within its lumen. The technique used made it possible to characterize the ultrastructural secretory pathways from the epithelial cells into the sac lumen. The results indicate that the ES may sense and respond to dynamic changes of the micro-osmotic environment probably via alterations in inner ear fluid homeosta

ISSN:0301-1569    

DOI:10.1159/000276420

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

To evaluate the mechanism of endocochlear potential (EP) and the validity of the two-component theory in its production, we perfused the endolymphatic space of normal and kanamycin-deafened guinea pigs with artificial endolymph containing 50 mM K+. The K+ activities and EP were simultaneously measured with a double-barreled K+ electrode during and after perfusion. The relationship between the mangitude of the electrogenic potential and K+ active transport was calculated and compared between the two groups of animals. The results showed that the positive component of the EP (positive EP) was mainly dependent on K+ active transport in the stria vascularis but included other electrogenic components not dependent on K+ active transport. The K+ and Na+ conductances (Gk and Gna) between the endolymph and perilymph were also calculated in the normal and kanamycin-deafened guinea pigs. The Gk was much lower in kanamycin-deafened guinea pigs but the Gna did not differ between the two groups of animals. The theoretical EP value during anoxia (negative EP) was consistent with that observed in each group. The difference in the negative EP was approximately 30 mV, but the steady-state EP did not differ between groups. It is concluded that EP is probably not the simple mathematical sum of the positive and negative potentials but involves more complex mechanisms.

ISSN:0301-1569    

DOI:10.1159/000276421

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

To elucidate efferent inhibitory mechanisms of the cochlear inner hair cells (IHCs), the effects of candidate efferent neurotransmitters on intracellular Ca2+ concentrations ([CA2+]i) in the isolated IHCs of guinea pig were determined using the Ca2+ sensitive dye fura-2 and digital imaging microscopy. In the presence of 1 mM acetylcholine (ACh), there was a gradual and reversible increase in [Ca2+]i. In the presence of 10µM ATP, there was a rapid and marked rise in [Ca2+]i. Thus, both ACh and ATP seem to be efferent neurotransmitters in IHCs of guinea pig. The ATP-induced elevation of [Ca2+]i in IHCs was suppressed when ACh was concomitantly applied; therefore, ACh may act as an antagonist of ATP-induced Ca2+ entry. With the independent addition of 10 µM calcitonin generelated peptide and 10 µM enkephalin, there were no significant increases in [Ca2+]i. These neuropeptides are putative candidates for the efferent neuromodulators in IHCs of the guinea

ISSN:0301-1569    

DOI:10.1159/000276422

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Human blood-group antigens are transiently expressed in developing cochlear hair cells. This temporal antigen expression seems to correspond to the main events of inner ear differentiation (e.g. hair cell development, synaptogenesis, ciliogenesis). In the present report, the cochlear expression of H human blood group antigen has been analyzed with the aid of the electron microscope. Ultrastructurally, cochleas stained with anti-H antibody exhibited an intense immunoreactivity on the apical hair cell membrane and on stereocilia. Cell surface glycoconjugates may serve a large number of functions and could be important during cell development. The temporal expression of H blood-group antigen in developing cochlear hair cells could be related to stereocilia differentiation.

ISSN:0301-1569    

DOI:10.1159/000276423

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The development of olivocochlear efferent fibers has been studied by means of the immunocytochemical detection of the growth-associated protein GAP-43. This study has been carried out in pre- and postnatal, developing, pigmented rats. Results indicate that olivocochlear efferents reach the developing auditory epithelium from embryonic day 18 on. GAP-43-like immunoreactivity persists in the organ of Corti until the beginning of the second postnatal month. The relationships between the expression of GAP-43 in olivocochlear efferent fibers and other plasticity-related phenomena are discussed.

ISSN:0301-1569    

DOI:10.1159/000276424

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The neurotoxic effects of two glutamate agonists, kainic acid (KA) and mono-sodium glutamate (MSG), were analyzed in the pigmented rat cochlea. Neural damage occurring after KA or MSG treatments were evidenced by the presence of a majority of swollen fibers in the inner spiral bundle. The use of diltiazem (DI), a Ca2+ L-channel antagonist, to prevent cochlear neural damage induced by glutamate agonists resulted in a significant increase of unswollen afferent nerve fibers. MSG-treated animals, after DI pretreatment, recovered the normal latency of the compound action potential, and only unswollen nerve fibers were observed.

ISSN:0301-1569    

DOI:10.1159/000276425

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Oxide ceramic materials (partial and total ossicular replacement prostheses) have been implants of preference for the reconstruction of the ossicular chain because of their excellent biocompatibility. The reaction on the surface of the implants takes place at three biodynamic levels according to the model of Stern’s bilayer. We investigated the adsorption of proteins, which is determined by the cellular reaction and degradation to the surface using radial immunodiffusion and immunohistochemical methods. First, ceramic implants of aluminum oxide, hydroxyapatite, glass ceramic and zirconium oxide have individual actual (i.e. biological) surfaces. With a perthometer and the contact-free laser Focodyn method we determined each actual (i.e. biological) surface of the various ceramic implants mentioned above. Using radial immunodiffusion, the adsorption of albumin, glycoprotein, plasminogen, fibronectin, IgA, IgG and IgM shows characteristic rates of adsorption to the respective ceramic surfaces in correlating to the actual surface. A cross-check with fluorescent antibodies confirmed the protein adsorption. The individual surface adsorption of the proteins remains characteristic and is the basis for the recording of cellular reactions after implantatio

ISSN:0301-1569    

DOI:10.1159/000276426

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The use of cartilage allografts is being discussed because of the possible transmission of the human immunodeficiency virus (HIV). To further delineate the possibility for an HIV infection of cartilage cells the susceptibility and permissivity of normal human chondrocytes to HIV-1 was assessed in culture. Isolated cartilage cells were incubated during 30 days with the HIV, testing the production of viral p24 antigens and the formation of particle-bound reverse transcriptase (RT) in the supernatant. The H9 cell line was used as positive control. The production of p24 antigen did not occur on chondrocytes during the whole culture time. Furthermore, no RT activity was detected throughout the entire experimental period. Our results indicate clearly that HIV was not able to infect cartilage cells under these in vitro conditions, and, conclusively, HIV infection of cartilage in vivo is improbable.

ISSN:0301-1569    

DOI:10.1159/000276427

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

In a prospective study, 126 children were followed for 1 year after the placement of tympanostomy tubes especially for recurrent acute otitis media. About 7 in 10 children remained free of middle ear infection and 1 in 10 showed frequent (i.e. 3 or more) episodes of otorrhea during the follow-up period. However, the most conclusive observation was that the otorrhea episodes were not equally distributed over the different ages: they were markedly more frequent in the group younger then 2 years old, although the prestudy infection rate was similar in all age groups. Furthermore, the incidence of middle ear infection was positively correlated with upper respiratory infection but not with other variables such as prestudy spontaneous perforations, contents of the middle ear, presence of the tube at the end of the study, and swimming habits. It seems that middle ear infection with ventilation tubes in place is influenced by age and upper respiratory infection as it is for acute otitis media in the population as a whole.

ISSN:0301-1569    

DOI:10.1159/000276428

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

After the failure of interferon monotherapies for head and neck cancer, an increasing number of combination experiments with chemotherapy and interferons have been carried out to improve the antiproliferative effect. In vitro drug testing requires sensitive assay to detect synergistic effects of tested combinations in order not to get false-negative results. The widely used MTT assay (3,4,5-dimethylthiazol-2,5-diphenyltetrazolium bromide) and the BrdU assay 5-bromo-2-deoxyuridine were compared. It could be shown that the BrdU assay is over 10 times more sensitive and that it reflects the cell proliferation status as shown by flow-cytometric analysis using double staining with BrdU. Labeling with BrdU also allows the estimation of the S phase time. Because of the direct effect of interferons on the cell cycle, the BrdU assay could be appropriate for proliferation studies using interferons.

ISSN:0301-1569    

DOI:10.1159/000276429

出版商:S. Karger AG    

年代:1993

数据来源: Karger