Pathophysiology of middle ear epithelium: a new role for prostaglandin E2

INTRODUCTION

Otitis media with effusion is a disease of the middle ear epithelium resulting from a decreased sol layer as well as increased mucus secretion and plasma-derived protein transudation, which causes mucus plugging. Because the epithelium keeps the middle ear cavities fluid-free and air-filled, we investigated its fluid transport capacities, which may be involved in both efficacy of the mucociliary clearance and drying-out of the posterior ear cavities (Yen PT et al: Acta Otolaryngol (Stockh) 113, 1993). We have established the absorptive capacity of middle ear epithelial cells in primary culture (Herman P, et al: Am J Physiol 262, 1992). However, the paucity of cells obtained by enzymatic digestion led us to develop a new model for further investigation of middle ear epithelial cell.

METHODS

We established a middle ear cell line (MESV) using simian virus 40 (SV40) infection of middle ear epithelial cells from the Mongolian gerbil.

RESULTS

Investigation of the transport processes using the short-circuit current technique showed that MESV cells retain most characteristics of the original middle ear epithelial cells. Transepithelial sodium transport from the apical to the basal side was responsible for the transepithelial lumen-negative potential difference.

CONCLUSION

The presence of high concentrations of prostaglandin E2 in the middle ear effusions has been documented. This work investigates the effect of prostaglandin E2 on the rate of transepithelial ion transport of MESV cells. Prostaglandin E2 increased the rate of electrogenic sodium transport by means of increase in the intracellular cyclic adenosine monophosphate (cAMP) content. Such a modulation of sodium transport in the course of otitis media could be responsible for the reduced periciliary sol layer that impairs the mucociliary clearance.

Localization of the human CD40 gene to chromosome 20, bands q12-q13.2

CD40 is a surface glycoprotein, member of the nerve growth factor receptor family, which is expressed on B cells and plays an important role in their development, growth, and differentiation. Using chromosomal in situ hybridization, we localized the CD40 gene to the long arm of chromosome 20, bands q12-q13.2. This localization correlates well with the mapping of the murine CD40 gene to the distal region of chromosome 2, syntenic to the human 20q11-q13 region.

Time-resolved polarized fluorescence studies of the temperature adaptation in Bacillus subtilis using DPH and TMA-DPH fluorescent probes

The validity of the concept of homeoviscous adaptation was tested for bacteria Bacillus subtilis. The Bacillus subtilis grown at 20 degrees C (referred to as Bs20) exhibit a considerable increase of branched anteiso-C15, the major fatty acid component of membrane lipids, relative to membranes grown at 40 degrees C (Bs40). The time-resolved fluorescence depolarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH) showed that these changes in the lipid composition are accompanied by changes in a mean lipid order. In particular, the DPH order parameters <P2> and <P4> measured in Bs20 membranes at 18 degrees C and in Bs40 membranes at 45 degrees C, respectively, tend to be equal. This effect was less pronounced for TMA-DPH. Our observations suggest that a physical parallel to the changes of lipid composition is the maintenance of an optimal lipid order in the hydrophobic core of the cytoplasmic membranes. It can be interpreted as a tendency of Bacillus subtilis to keep the lateral pressure in its membranes at an optimal value, independent of the temperature of cultivation.

[Transformation of hepatic adenoma into hepatocellular carcinoma in patients with prolonged use of oral contraceptives]

Liver cell adenomas were relatively rare until the use of oral contraceptives. Most of these tumors have occurred in otherwise healthy young women who have been exposed to oral contraceptives. The treatment of this condition remained controversial for a long time. However, bleeding is still a frequent complication and can lead to a significant mortality rate. The better surgical results in hepatic resection, due to technological advances, has contributed to the indication of surgical management as therapeutic option in hepatic cell adenoma. Some authors believe that liver cell adenomas were potentially premalignant and could degenerate into hepatocellular carcinoma but there is very few well documented reports of this transformation. We report our experience in the management of liver cell adenoma.

Primary culture of Reissner's membrane from the gerbil: growth, morphologic features, and characterization

To overcome the technical difficulties encountered in investigating the physiology of Reissner's membrane (RM), primary culture of RM was established. Minute explants obtained by mechanical dissociation were seeded on impermeable substrate coated with collagen type I in serum-free, hormone-supplemented medium. Within 2 weeks, a large cultured area was obtained which reproduced the two cell layers of the original explant. One layer, deep or superficial depending on the side to which the explant adhered, was made of cells exhibiting light and electron microscopy characteristics of an epithelium. Immunohistochemical methods revealed that they expressed cytokeratin, demonstrating their epithelial nature. The second layer was made of mesenchymal cells. This study suggests that cell culture of RM will facilitate further investigation of its physiology.

Ion transport processes and middle ear physiopathology. An experimental approach using cell culture

The role of the middle ear (ME) epithelium is primarily to keep the cavities air-filled and fluid-free. This condition requires elimination of mucus and cellular debris from the tympanic cavity by the ciliary activity. This clearance activity may be related to active ion transport processes in the epithelium. This paper presents a review of the experimental data suggesting the existence of ion transports in ME, and demonstrating the contribution of the culture of ME epithelial cells to the investigation of ion transport properties. Primary cultures of ME epithelial cells from Mongolian gerbils (Meriones unguiculatus) were undertaken. Polarized monolayers exhibited domes on non-porous supports. On porous supports, the absorptive function was shown to be related to a Na+ absorption from apical to basal sides of the epithelium, by means of apical amiloride-sensitive Na+ channels and basolateral Na+, K(+)-ATPase. In turn, this sodium absorption would generate an osmotic gradient and drive a water flow. An amiloride-induced chloride transport is also suggested. A hormonal modulation of these ion transport properties might play a role in the development of the mucociliary impairment that initiates chronic otitis media. The establishment of a middle ea cell line using wild-type SV 40 infection is in progress. This might provide further information on the physiology of the ME.

Middle ear cell line that maintains vectorial electrolyte transport

The middle ear epithelium plays a major role in keeping the temporal bone cavities fluid-free and air-filled, which is a mandatory condition to allow optimum transmission of the sound vibrations from the tympanic membrane to the inner ear. Previous works have recently established the absorptive function of the middle ear epithelium, using primary cultures derived from Mongolian gerbil (Meriones unguiculatus). Because of the paucity of cells as obtained by enzymatic digestion, we developed a middle ear cell line (MESV) using wild-type SV40 infection of primary culture of Mongolian gerbil's middle ear epithelial cells. Transformation was attested by nuclear expression of SV40 large T antigen, prolonged in vitro passages (presently beyond 50 passages), and tumor-inducing ability when subcutaneously injected in athymic mice. Transport properties were evaluated after the fifteenth passage. MESV cells retained most cardinal properties of the original middle ear epithelial cells: cell polarization was evidenced by the presence of mature junctional complexes that separate the cell membrane in two distinct domains, with apical microvilli at the luminal side, and by vectorial sodium transport responsible for the transepithelial lumen-negative potential difference (-9.3 +/- 0.14 mV in culture conditions (n = 9), -2.1 +/- 0.25 mV after overnight growth factors and serum deprivation). Short-circuit current was, like in primary cultures, mainly related to a sodium transport occurring through amiloride-sensitive apical sodium channels, since apical addition of amiloride (10(-5) M) reduced ISC from 7.0 +/- 1.4 to 0.6 +/- 0.1 microA/cm2 (P < 0.01, n = 6). Cellular cAMP content was increased by isoproterenol and prostaglandin E2 from 40.5 +/- 5.6 to 258.5 +/- 17.3 and 55.6 +/- 6.2 pmol/mg protein per 5 min, respectively (P < 0.05, n = 10). Isoproterenol and prostaglandin E2 increased ISC with very similar maximal effects: isoproterenol (10(-4) M) increased ISC from 5.73 +/- 0.31 to 12.77 +/- 0.39 microA/cm2, while prostaglandin E2 increased ISC from 5.47 +/- 0.21 to 12.87 +/- 0.42 (n = 3). Since amiloride (10(-5) M) abolished this stimulation, this may be related to an increase of the electrogenic sodium transepithelial transport. The MESV cell line could provide an interesting tool as a model of middle ear epithelial cells for the study of pathophysiological modulations of ion transport.

[Contribution of cell culture to the study of cochlear endolymph]

Investigation of the mechanisms involved in the secretion of cochlear endolymph is hindered by the heterogeneity, the fragility, and the difficulty of access to the secretory structures of the inner ear, i.e. stria vascularis and Reissner's membrane. Cell culture may overcome these limitations and allow the study of the epithelial transport processes. Cultured cells derived from gerbil's explants of stria vascularis and Reissner's membrane presented morphological and immunohistochemical properties similar to those of the native cells. Investigation by the patch clamp technique of the apical membranes of marginal-like cells showed the presence of non specific cationic channels that could allow passive K+ flow towards endolymph and, thus, play a major role in the production of endolymph. Biochemical studies demonstrated that a cAMP production by these marginal-like cells. Primary culture of stria vascularis and Reissner's membrane is a suitable model to further investigate the physiology of endolymph production.

c-myc antisense oligonucleotides inhibit the colony-forming capacity of Colo 320 colonic carcinoma cells

Colo 320 cells are colonic carcinoma cells known to express abundant c-myc mRNA. Based on the response of several hematopoietic cell lines to chemical inducers of differentiation, we reasoned that such agents might have similar inductive activity in Colo 320 cells. Accordingly, we exposed Colo 320 cells to 5 mM sodium butyrate (NaBT) for 7 d. C-myc expression decreased threefold and self-replicative potential decreased (defined as a greater than 60% decrease in colony-forming capacity in soft agar that did not contain inducer). In an effort to demonstrate a direct cause and effect between myc expression and the colony-forming capacity of Colo 320 cells, we exposed these cells to a 15-base antisense c-myc oligonucleotide (complementary to the translation initiation region of exon II). Cells were also exposed to equimolar (20 microM) amounts of sense and missense oligonucleotides. Subsequently, cells were incubated at 10, 20, 30, and 40 microM antisense DNA for 16 h, then washed and plated in oligonucleotide-free agar medium. We demonstrated that: (a) the oligomers were stable in the extracellular medium and in the cell cytoplasm; (b) the uptake of the oligonucleotides was 0.7%; (c) sense and missense oligonucleotides had no effect on colony-forming capacity; and (d) the antisense c-myc oligonucleotide resulted in a 40-75% concentration-dependent decrease in colony-forming capacity. The specific inhibition of colony-forming capacity by antisense DNA suggests that the role of myc expression in Colo 320 cells is similar to its role in hematopoiesis, and that the failure to inhibit myc expression maintains colony-forming capacity. This system provides a new strategy for inducing differentiation and may provide further insight into the genetic factors that govern the process of colonic carcinogenesis.

Ion transport by primary cultures of Mongolian gerbil middle ear epithelium

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)

[Differential diagnosis of cholestasis in pancreatic cancer and chronic pancreatitis]

The clinical, biochemical and radiological data of 25 patients with carcinoma of the head of the pancreas were compared with the same parameters of 25 patients with chronic pancreatitis producing cholestasis. History of alcohol abuse, pruritus and palpable gallbladder were the only clinical findings useful for the differential diagnosis. Plasma bilirubin levels were significantly higher in patients with malignancy (20.0 +/- 14.3 vs 2.5 +/- 2.4) but the course of the bilirubinemia was similar in the two groups after hospital admission. Preoperative ultrasound and cholangiography were usefull in differentiating both groups of patients. Sensibility of a point score based on significant differences was 100% for pancreatitis and 96% for malignancy.

A new method of measuring dimensional change

A new method of measuring linear dimensional change in denture base resins is presented and its precision in determining distances between two points was investigated. Chrome steel ball bearings 1.57 mm in diameter were invested in a stone mold and were used to record measurements by a reflection from the surface of the ball bearings. The accuracy of this method was determined by performing repeated measurements between two points in a stone mold. Random measurements were made to an accuracy of 0.002 mm. The dimensional change of light-cured, heat-cured, and self-cured denture base resins was also determined with this method, followed by an analysis of variance of the data. The findings support the accuracy and reproducibility of this new method in recording linear measurements. The dimensional changes of all three resins were different from each other after the specimens were processed and stored in distilled water for 7 days at 37 degrees C.

[Splenic abscess: report of 8 cases and review of the literature]

Eight patients with splenic abscess are reported. Etiological factors were sepsis, mainly due to endocarditis. Diagnosis was made by ultrasonography and computed tomography scans. Splenectomy was performed in four cases, transcutaneous drainage in three and abscess puncture in one case. Mortality was 12.5% (1/8). Since the introduction of US and CT scans early diagnosis and treatment was possible by which the mortality decreased.

Transmembrane potential measurement with carbocyanine dye diS-C3-(5): fast fluorescence decay studies

The mechanism of carbocyanine dye diS-C3-(5) fluorescence intensity variations with transmembrane potential changes has been studied using time-resolved fluorescence spectroscopy. Clear evidence is given of the transmembrane-potential-dependent partition of the dye among various sites with different fluorescence lifetimes. It was found that fluorescence decay profiles reflect the transmembrane potential changes.

Computed tomography of primary malignant fibrohistiocytoma of the lung

A case of malignant fibrous histiocytoma of the lung is reported in pediatric patient-uncommon location as well as age group.

Effect of diltiazem on plasma glucose, insulin and glucagon during an oral glucose tolerance test in healthy volunteers

The effect of the calcium antagonist, diltiazem, on glycoregulation was investigated in 12 healthy volunteers using a standard glucose tolerance test. No significant change was observed in plasma glucose, insulin or glucagon levels after oral treatment for B days with diltiazem 180 mg/day.

Organicity and mental retardation: organic mental syndrome battery

Fifteen mentally retarded children were tested and compared to 10 normal school children. They were administered a battery of tests reflecting organic brain disease, consisting of the Face-Hand, Midline Crossing and Independent Eye Movements Tests. Normals performed correctly 98% of the time on the three combined tests, while the mentally retarded scored only 34% correct. There was a significant correlation between IQ and this battery of tests (the 'OMSB'). When the IQ and OMSB were conflicting, a repeat of the former indicated that the IQ value was erroneous. The OMSB may be useful along with IQ testing as a rapid screening method to evaluate the presence of organicity and its severity.