Distribution of DMT 1 within the human glandular system.

BACKGROUND & AIMS: DMT1 is a transmembrane protein which transports the divalent metal ions Fe2+, Zn2+, Cu2+ and Mn2+. Although DMT1 has been functionally linked to duodenal absorption and cellular utilisation of iron hardly anything is known about its distribution and potential role within the human glandular system. METHODS: Two polyclonal antibodies were raised to study the expression of DMT1 in tissues obtained from human corpus by the means of immunocytochemistry and Western blotting. RESULTS: All antibodies specifically detected a 60 kD protein band referring to human DMT1. Significant amounts of DMT1 expression were detected on the luminal site of organs, which are involved in excretion/re-absorption processes, such as salivary glands, pancreas, biliary tract and gallbladder. CONCLUSIONS: Our results suggest that DMT1 may be of pivotal importance for the regulation of metal ion homeostasis within organs involved in absorption and excretion of ions.

The time-course of furosemide-induced strial changes in guinea pigs after pretreatment with daltroban.

It was shown previously (Ernst et al., 1989) that pretreatment of guinea pigs with a thromboxane (TX) receptor antagonist attenuates the decline of the endocochlear potential (EP) induced by furosemide. The present paper is aimed at investigating a possible correlation between the electrophysiological data and ultrastructural changes of the stria vascularis by electron microscopy. The dosages of 40, 60, and 80 mg/kg furosemide were injected after the pretreatment with the TX receptor antagonist daltroban and compared to controls which were injected with furosemide only. It was found at all furosemide concentrations that the strial changes 10 min after injection were nearly unchanged against controls. 30 min after furosemide injection, the most pronounced changes were seen when pretreating the animals: a clear reduction of the marginal cell swelling and edema in general were observed at 40 and 60 mg/kg furosemide. The guinea pigs injected with 80 mg/kg furosemide after pretreatment displayed nearly the same changes as controls.

Localization of chat-like immunoreactivity in the vestibular endorgans of the rat.

In vertebrates acetylcholine (ACh) has been generally considered as a neurotransmitter of the vestibular efferent system. The precise localization and innervation of the cholinergic nerve endings in the vestibular sensory periphery is still unknown. We examined choline acetyltransferase (ChAT)-like immunoreactivity in all five endorgans of the rat vestibule with light and electron microscopy using a modified pre-embedding immunostaining technique. The results were: (1) ChAT-like immunoreactivity was widespread in all five endorgans of the vestibule and confined to the vesiculated efferent nerve endings. (2) Two types of ChAT-like immunostained nerve endings can be identified according to their size and innervation pattern: a large nerve ending and a small--middle size one. (3) Vestibular endorgans differ in their ChAT-like immunoreactivity: staining is dense in the macula of the utricule and the three ampullary cristae, but less so in the macula of the saccule. (4) We found also a regional difference of the ChAT-like immunostaining in ampullary crista. ChAT-like immunostained nerve endings were predominant in the periphery close to the semilunar plane, and less in density in the central area. These findings demonstrate that ACh is a major neurotransmitter in the vestibular efferent system.

Immunocytochemical detection of choline acetyltransferase in the human organ of Corti.

In the mammalian cochlea acetylcholine has been considered a major neurotransmitter of the lateral and medial efferent fibers. The aims of the present study were to investigate the expression of ChAT in the human cochlea and to develop a new method for immunohistochemical investigations in the human cochlea both at the light and electronmicroscopic level. We thus examined the ChAT-like immunoreactivity in the human inner ear using light and electron microscopy with a pre-embedding technique. Our present results agree with the previously published data acquired in rodent species. The ChAT-like immunostaining could be found in the inner spiral fibers, the inner spiral bundle, tunnel crossing fibers and at the base of the outer hair cells. No staining was noted in the negative controls experiments, while rat cochleas used as positive controls showed the usual ChAT-like immunostaining as described above. The main difference between human and rat cochleas was that the efferent nerve supply seems to be less pronounced in the human cochleas.

Dendritic cells in the normal human tympanic membrane.

Dendritic cells (DCs) are antigen-presenting cells that possess an outstanding capacity to initiate primary immune responses. They reside in the tissues in an immunologically immature state. Upon antigenic challenge in vivo or short-term culture in vitro, they undergo a maturation process and turn into mature "lymphoid DCs." Langerhans cells (LCs) of the epidermis were identified as members of this DC system. They have been demonstrated in cholesteatoma matrix and in inflamed tympanic membranes, but the normal tympanic membrane was hitherto thought to be devoid of them. To clarify this question, we removed 12 normal tympanic membranes postmortem and processed them for a sheet preparation. The epidermal layers were peeled off and immunostained with the following monoclonal antibodies: HLA-DR, OKT6/CD1a, and LAG (specific for the Birbeck granules of LCs). Two tympanic membranes were also processed for routine electron microscopy. In all epidermal sheets a dense network of DCs could be demonstrated. They showed a positive immunostaining reaction with HLA-DR, but a negative one with OKT6 and LAG. Thus, they differ in their immunohistochemical properties from typical epidermal LCs. At the ultrastructural level, DCs could also be identified, but without the typical Birbeck granules. This explains the negative reaction with the LAG antibody. These findings were extended and supported by a tissue culture examination of three normal tympanic membranes. After 3 days, typical "veiled" cells (ie, mature DCs), showing positive immunostaining with HLA-DR, could be recovered from the culture medium. In an oxidative mitogenesis assay, these cells displayed strong stimulatory capacity for resting T lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

A study of neurotransmitters in human inner ear. Preservation of human temporal bone and value of organ donation for inner ear research.

Twenty-nine human temporal bones (TBs) from 3 different groups of patients were used to investigate an effective preservation method of the inner ear and to study the suitability of TBs from organ donors for human inner ear research. Inner ears were fixed by perilymphatic perfusion and immersion fixation. Choline acetyltransferase (ChAT) and gamma-aminobutyric acid (GABA) activities were detected either by an indirect immunostaining method or by the peroxidase-anti-peroxidase (PAP) technique. The results show that the cytoarchitecture of the sensory epithelia is excellently preserved in specimens fixed within 2 h after death. ChAT- and GABA-immunoreactivities were revealed in the efferent nerve endings and fibers of the cochlea. Morphological preservation of the sensory epithelia was also good in specimens fixed within 5 h after death. However, inner ear sensory epithelia of organ donors that had died from head trauma and were in the definite brain death state for at least 7 1/2 h were severely damaged and showed cellular debris due to autolysis, although they were fixed within 2 1/2 h after death. The mechanisms underlying this damage of the sensory epithelia are discussed.

[N-acetylneuraminic acid (sialic acid) as a tumor marker in head and neck cancers]. / N-Azetylneuraminsäure (Sialinsäure) als Tumormarker bei Kopf-Hals-Karzinomen.

N-acetyl-neuraminic-acid (sialic acid) is a natural component of the cell surface. Cancer cells show a higher concentration of sialic acid in the cell membrane, and the serum also shows an elevated level of sialic acid. The concentration of sialic acid was measured in the serum of 76 new tumour patients and 113 previously treated patients who were clinically free of recurrence. The primary tumour was classified as T1-T4 according to the UICC classification. A further group consisted of patients with recurrent tumours. The values were compared with the sialic acid concentration in the sera of 63 healthy probands. Patients with manifest tumours showed an increased level of sialic acid that correlated with the extent of the tumour. The sialic acid level in 71% of patients with a recurrence lay above the upper limit of normal (82 mg/dl) recorded in the sera of healthy probands. The measurement of the serum sialic acid is a useful parameter for early detection of recurrence.

Intermediate filaments in the cochleas of normal and mutant (w/wv, sl/sld) mice.

Using monoclonal and polyclonal antibodies to intermediate filaments in the cochleas of normal and mutant mice, we were able to distinguish between different cell types of the stria vascularis. Immunostaining for vimentin was found in the intermediate and basal cells of the stria vascularis of the normal mice. In contrast, vimentin was seen to stain only the basal cells in the mutant mice, confirming our previous findings of the absence of intermediate cells in these cases of hereditary deafness. Immunostaining for cytokeratin was identical in both the mutant and control mice.

Innervation of cholinergic vestibular efferent system in vestibular periphery of rats.

The innervation of cholinergic efferent fibers in the vestibular endorgans of the rats was investigated using a modified preembedding immunostaining technique of immunoelectron microscopy. A monoclonal antibody to choline acetyltransferase (ChAT) was used as a marker of cholinergic fibers. It was found that there were four types of cholinergic innervation in the vestibular endorgans of the rat: (1) cholinergic nerve endings formed axo-dendritic synapses with afferent chalice surrounding the type I sensory hair cells; (2) cholinergic nerve endings formed axo-somatic synapses with type II hair cells; (3) cholinergic fibers synapse with afferent nerve fibers and (4) a synaptic contact developed between cholinergic nerve endings. The results demonstrated that a multiform innervation of the cholinergic efferents exists in the rats vestibular periphery.

The effects of locally applied PAF in inner ear morphology.

The effect of a PAF-containing artificial perilymph (10(-7) M PAF) on the ultrastructure of the stria vascularis was investigated in acute perilymphatic perfusion experiments in guinea-pigs. We have shown previously that locally applied PAF at this concentration reversibly changes the endolymphatic potential (EP) (Ernst et al., 1989a) which suggests an interference with ion transport. Controls which were perfused with artificial perilymph as well as experimental animals were decapitated at 10, 30 and 60 min after starting the perfusion. Subsequently, the cochleae were removed and evaluated by electron microscopy. The histological findings do not correspond to those obtained with different substances modifying ion transport in the stria vascularis, e.g., ouabain, loop diuretics. There are only minor strial changes in our study. The relevance of PAF in cochlear physiology is discussed.

A quantitative study of nerve fibers in the human facial nerve.

The facial and intermediate nerves were quantitatively evaluated in seven patients who died from systemic malignancies not involving the facial nerve. In addition, five of the specimens were also qualitatively evaluated by measuring the total and axon diameters of the facial and intermediate nerve fibers. In two cases the facial nerve fibers were counted at five different levels. The total number of myelinated nerve fibers in the facial nerve varied from 7500 to 9370. The total number of myelinated nerve fibers in the intermediate nerve varied between 3120 and 5360. The peak diameter of the facial nerve axon was between 4 and 6 microns, and was between 2 and 3 microns in the intermediate nerve. When comparing nerve segments at different anatomical levels, the largest amount of nerve fibers was found at the level of the middle mastoid portion. However, this number did not reach the amount of nerve fibers counted in the internal acoustic meatus.