Implantable hearing aid. Report of the first human applications

To our knowledge, this is the first report of human application of the partial implantable hearing aid. Direct driving of the stapes by an ossicular vibrator of piezoelectric ceramic bimorph is the fundamental mechanism of this device. Acoustic signals received by a microphone were transmitted to the external link coil after amplification. By means of electromagnetic induction, the internal coil placed under the retroauricular skin excited electroacoustic energy, which is transmitted to the vibrator directly coupled with the stapes. The device used in this first patient has been functioning for longer than one year. Excellent frequency response of the vibrator and highly efficient direct transmission of electroacoustic signals to the inner ear gave rise to acoustic perception of superior quality that could not be obtained by other surgical or rehabilitative measures.     

Osteopontin regulates adhesion of calcium oxalate crystals to renal epithelial cells.

BACKGROUND: The association of calcium crystals with renal tubular cells is an important factor during the formation of urinary stones. We previously reported the strong expression of osteopontin (OPN) on renal tubular cells in the stone-forming kidney, suggesting that OPN plays a role in the crystal-cell interaction. In the present study, we examined the biological consequences of inhibiting OPN expression at the translational level on the formation and adhesion of crystals. METHODS: We synthesized antisense OPN expression vector (pTet-OPNas) using the tetracycline-regulated expression system. The pTet-OPNas was constructed using a mouse OPN cDNA sequence in an inverted (antisense) orientation. Two clones (NRK-52E/ASs) were identified by transfection of pTet-OPNas into NRK-52E cells and they showed a marked reduction of OPN synthesis in the absence of tetracycline. Calcium oxalate (CaOx) crystal suspension was spread homogeneously on top of the NRK-52E cells. After incubation, the association of CaOx crystals and cells was visualized by scanning electron microscopy. RESULTS: Intact NRK-52E cells, NRK-52E cells transfected with empty vector and tetracycline-treated antisense clones (NRK-52E/ASs), under identical conditions, were associated with CaOx crystals. In contrast, the expression of antisense OPN prevented the association of CaOx crystals with NRK-52E cells. CONCLUSIONS: Osteopontin plays a crucial role in the adhesion process of CaOx crystals to renal tubular cells in stone formation.     

Occlusion of the abdominal aorta caused by enlargement of the false lumen after graft replacement for a DeBakey type IIIb dissecting aneurysm: Report of a case

(Received for publication on July 10, 1997; accepted on Mar. 10, 1998)     

Incidence of inflammation in completely impacted lower third molars

The influence of ageing and the contact of the adjacent tooth on purulent inflammation associated with the completely impacted lower third molar was assessed in 26 patients with clinical symptoms of infection out of 800 patients who had roentgenographically-confirmed completely impacted lower third molars. These 26 patients were 23 years of age or older. The 9 with pain alone ranged from 25 to 44 years of age, whereas the 17 patients with inflammation ranged from 29 to 67 years of age, and non-contact to adjacent tooth was associated with purulent inflammation in older patients, indicating completely impacted lower third molars may cause pain only until 45 years of age; but purulent inflammation occurs even in the group of non-contact to adjacent tooth after 45 years of age. The authors recommend that a completely impacted lower third molar should be removed if the risk factors of advanced age and contact with the adjacent tooth are present.     

Evidence for the neurotransmitter role of norepinephrine in the ventral thalamic nucleus of the guinea pig: Localization, uptake and release

The localization, uptake and release of norepinephrine (NE) by the isolated guinea pig ventral thalamic nucleus (VT) were studied to determine the possible neurotransmitter role of this catecholamine. The NE content in the VT was 356 +/- 24 ng/g wet weight and intraneuronal localization of NE was demonstrated in the VT by histofluorescence. [3H]NE accumulation into the VT slices was about 3 times that of [3H]NE (10(-7) M) in the medium 10 min after incubation. Kinetic analyses indicated 2 components of [3H]NE accumulation, one representing a high (Km1 4 X 10(-7) M and Vmax1 1.5 pmol/mg/10 min) and a low (Km2 1.8 X 10(-6) M and Vmax2 5 pmol/mg/10 min) affinity uptake system. Desmethylimipramine (10(-5) M) reduced the high affinity uptake of [3H]NE by 30% of the control value. Electrical stimulation of the slices increased the efflux of [3H]NE from tissues preloaded with [3H]NE, in a current- and frequency-dependent fashion. The release of [3H]NE induced by stimulation of up to 1 mA was inhibited by tetrodotoxin (10(-6) M) or Ca-free medium containing EGTA (10(-4) M). These findings provide strong evidence for the neurotransmitter role of NE in the VT.     

Involvement of tissue plasminogen activator-plasmin system in depolarization-evoked dopamine release in the nucleus accumbens of mice

Tissue plasminogen activator (tPA), a serine protease, catalyzes the conversion of plasminogen to plasmin. In the present study, we investigated the role of the tPA-plasmin system in depolarization-evoked dopamine (DA) and acetylcholine (ACh) release in the nucleus accumbens (NAc) and hippocampus, respectively, of mice, by using in vivo microdialysis. Microinjection of either tPA or plasmin significantly potentiated 40 mM KCl-induced DA release without affecting basal DA levels. In contrast, plasminogen activator inhibitor-1 dose-dependently reduced 60 mM KCl-induced DA release. The 60 mM KCl-evoked DA release in the NAc was markedly diminished in tPA-deficient (tPA-/-) mice compared with wild-type mice, although basal DA levels did not differ between the two groups. Microinjections of either exogenous tPA (100 ng) or plasmin (100 ng) into the NAc of tPA-/-mice restored 60 mM KCl-induced DA release, as observed in wild-type mice. In contrast, there was no difference in either basal or 60 mM KCl-induced ACh release in the hippocampus between wild-type and tPA-/-mice. Our findings suggest that the tPA-plasmin system is involved in the regulation of depolarization-evoked DA release in the NAc.