Proper fitting of hearing aids performed by well-trained medical professionals results in a very low incidence of significant complications. Perforation of the tympanic membrane with impaction of earmold material in the middle ear or mastoid bowl may occur and can be successfully managed by standard otologic surgical techniques.

The transport properties of Mongolian gerbil middle ear epithelial cells grown in primary culture were studied. These cells formed polarized monolayers that exhibited domes on nonporous supports. On porous supports, monolayers developed an apical-negative transepithelial electric potential difference (VT = -37.2 +/- 2.7 mV) and a transepithelial resistance (RT = 519 +/- 56 omega.cm2). The short-circuit current equivalent (Ieq) was 62.4 +/- 6.2 microA/cm2 (mean +/- SE, n = 15). Na+ and Cl- accumulated in the basal bath and generated a basolateral hyperosmolarity that drove a net water flow. Amiloride (10 microM), when added to the apical but not to the basal bath, induced a 23.4 +/- 1.5 mV and 44.1 +/- 1.3 microA/cm2 decrease of VT and Ieq, respectively, while RT increased by 403 +/- 69 omega.cm2 (P less than 0.001, n = 15). Exposure of the monolayers to a low-Cl- solution (30 mM) enhanced the transepithelial potential, possibly by means of a Cl- secretion through apical Cl- channels. Isoproterenol (10(-4) M basolateral) increased intracellular adenosine 3',5'-cyclic monophosphate (cAMP) content (concentration of half-maximal response = 2.5 x 10(-7) M) and decreased VT, RT, and Ieq. The isoproterenol-induced fall of VT occurred even in the presence of low-Cl-solutions. This suggested an increase of the paracellular pathway conductance, although there was no significant modification of the mannitol permeability.(ABSTRACT TRUNCATED AT 250 WORDS)

Ex vivo expanded bone marrow CD34 ؉ DR ؊ cells could offer a graft devoid of malignant cells able to promptly reconstitute hemopoiesis after transplant. We investigated the specific expansion requirements of this subpopulation compared to the more mature CD34 ؉ and CD34 ؉ DR ؉ populations. The role of stromal factors was assessed by comparing the expansion obtained when the cells were cultured in (1) long-term bone marrow culture (LTBMC) medium conditioned by an irradiated human BM stroma (CM), (2) medium supplemented with 15% FBS (FBSM) and (3)

Autologous bone marrow (BM) transplantation for acute myeloid leukaemia (AML) in complete remission (CR) is frequently followed by a slow haemopoietic recovery. We assessed the haemopoietic capacity of purified BM stem cell (CD34+ DR-) and progenitor cell (CD34+ DR+) populations from patients with AML in CR, and compared these data with those of normal BM. The feasibility of ex vivo expansion in stroma-conditioned medium supplemented with cytokines was also investigated. The number of CFU-GM produced by initial patient CD34+ DR- cells was decreased compared to normal, whereas these values were similar to normal for CD34+ DR+ cells. BFU-E, HPP-CFC and LTC-IC were reduced for both patient CD34+ DR- and CD34+ DR+ subpopulations. In contrast to normal, the patient CD34+ DR- fraction was not enriched in LTC-IC. CFU-GM expansion from patient CD34+ DR- cells was poor and decreased after 14 d of culture. No HPP-CFC expansion could be observed for patient cells. LTC-IC were below the level of detection after 14-21 d of expansion culture of CD34+ DR- patient cells, whereas they were variably maintained or expanded for normal cells. After expansion culture, cytogenetic and/or FISH analyses did not reveal the anomalies present at diagnosis, regardless of the cell subpopulation analysed. In conclusion, BM cells of patients with AML in CR show a profound defect at the level of a stem cell enriched population. No meaningful ex vivo expansion could be obtained in culture conditions allowing for a significant expansion from a normal stem cell population.

No abstract

The nature of the cellular reactions underlying contact photoallergy to a salicylanilide compound has been examined. The typical dermal mononuclear cell infiltrate in positive photopatch tests has been shown to consist of cells staining negatively for lysosomal hydrolytic enzymes. Furthermore, peritoneal macrophages from salicylanilide-photosensitive guinea pigs lost their staining capacity for lysosomal enzymes when exposed to specific antigen. The relationship of these findings to the pathogenesis of cutaneous damage in photoallergy is discussed.

Mucus and cellular debris are eliminated from the middle-ear cavity through the E-tube by the mucocüiary system. Depth of the periciliary fluid layer is thought to be regulated by epithelial ion transport activity. Since impairment of the mucocüiary system is a key step in the development of otitis media with effusion, we investigated the ion transport mechanisms of the middle-ear epithelium using the middle-ear MESV cell line. ATP has been shown to modulate ion transport as well as various cellular functions in several cell types via purinoceptors. In order to investigate a possible modulation of the transport activity of MESV cells, we evaluated short-circuit current (I_sc) changes in response to specific stimulation of putative purinoceptors by ATP and its various analogs. ATP dramatically increased I_sc, while adenosine had no effect, thus demonstrating the presence of P₂ receptors according to the original classification by Burnstock. The rank order of potency of purinoceptor agonists for stimulation of Isc on the apical side (ATP > UTP > γ-SATP>>β-SADP > 2-methylthio-ATP, 2MeSATP > β, γ-methylene-ATP, βγ-MeATP) and on the basolateral side (ATP > γ-SATP > UTP>>β-SADP > 2MeSATP > βγ-MeATP), along with studies using selective antagonists and intracellular calcium measurements are consistent with a P_2Y receptor subtype. The ATP-induced increase in I_sc was related to sodium transport. This modulation might be of importance in stress conditions such as inflammation.

The middle ear epithelium and respiratory epithelia share basic properties such as homeostasis of air-filled cavities and mucociliary clearance toward the pharynx. With the middle ear SV40-transformed (MESV) cell line, we used the short-circuit current (Isc) technique to investigate changes in ion transport induced by oxidants. Xanthine and xanthine oxidase on the basal side of the monolayers dramatically increased Isc up to 50%. This effect was not affected by superoxide dismutase or mannitol, but could be blunted by catalase or 1,3-dimethyl-2-thiourea. Increasing concentrations of H2O2 from 10(-5) to 5 x 10(-4) M produced a dose-dependent increase in Isc from 0.26 +/- 0.16 up to 4.21 +/- 0.43 microA/cm2 (P < 0.05, n = 5). Concentration of half-maximal stimulation (EC50) was 4.68 x 10(-5) M. This effect was inhibited by indomethacin and was related to a sodium transport, since the H2O2-induced increase in Isc could be prevented or abolished by 1) apical addition of benzamil (10(-6)M) and 2) substitution of sodium with N-methyl-glucamine. H2O2 exposure also induced indomethacin-sensitive increase in released prostaglandin (PG) E2 (EC50 = 5.62 x 10(-5) M) and in cAMP content (EC50 = 3.95 x 10(-5) M) with similar kinetics. These results suggest that exposure of MESV cells to oxidants stimulates the production of PGE2, which in turn increases the transepithelial sodium transport rate.