A New Hypothesis on the Frequency Discrimination of the Cochlea.

OBJECTIVE: Medial olivocochlear efferent (MOCE) neurons innervate outer hair cells (OHCs) of the cochlea, which in turn leads to basilar membrane motion. We hypothesized that MOCE-induced alterations in basilar membrane motion, independent of traveling waves, is responsible for the cochlear frequency discrimination of sound. MATERIALS AND METHODS: Eleven guinea pigs underwent bilateral otoscopic and audiologic evaluations under general anesthesia. The study comprised two parts. Part I (n=11) included spontaneous otoacoustic emission (SOAE) recordings with or without contralateral pure-tone acoustic stimuli (1 and 8 kHz) at 60 dB sound pressure level (SPL). Part II involved pure-tone (1 or 8 kHz) acoustic trauma in the right ears of two randomly selected subgroups (G1: 1 kHz; n=4 and G8: 8 kHz; n=4). The remaining three animals served as controls. After frequency-specific deafness was confirmed by distortion product otoacoustic emission (DPOAE), SOAEs were recorded in the left ears in the presence of a contralateral pure-tone (1 and 8 kHz) stimulus of 60 dB SPL. Furthermore, the surface of the organ of Corti was examined by scanning electron microscopy (SEM). RESULTS: The contralateral pure tone led to frequency-specific activation in SOAEs in part I (without trauma) and part II (with trauma) measurements. SEM showed heterogeneous OHC damage along the cochlea in traumatized ears with pure tone. CONCLUSION: We suggest that MOCEs convey acoustic information from traumatized ears to intact ears. Traumatized ears can show frequency-specific activation in the presence of diffuse damage in OHCs that excludes the passive transmission of the pressure wave from the perilymph to the basilar membrane.

Comparison of bone prefabrication with vascularized periosteal flaps, hydroxyapatite, and bioactive glass in rats.

BACKGROUND: Periosteal flaps possess osteoprogenitor cells and an osteoinductive potential that can be further augmented by combination with a biodegradable scaffold; therefore, various osteoconductive and osteostimulative biomaterials are frequently combined with periosteal flaps in studies of bone prefabrication. An experimental study was designed to determine and compare the contribution of bioactive glass and hydroxyapatite to osteoneogenesis in rats when combined with a periosteal flap. MATERIALS AND METHODS: In 60 Sprague Dawley rats, saphenous artery periosto-fasciocutaneous island flaps were transposed to abdomen. In group 1, the flap was left alone, in group 2, an empty artificial pocket made of Gore-Tex (W. L. Gore & Associates, Inc.; Flagstaff, AZ) was sutured onto the periosteal layer, and in groups 3 and 4, the pocket was filled with bioactive glass and hydroxyapatite, respectively. Following sampling for histological analysis, a 4-point scoring system was used to grade inflammatory cell infiltration, osteogenesis, angiogenesis, and cell migration into the bioactive material. RESULTS: The combination of the periosteal flap with any of the bioactive materials resulted in significantly higher percentages of animals exhibiting osteogenesis (80% in hydroxyapatite group and 93.3% in the bioactive glass group; p = 0.0000528) and angiogenesis. Comparison of the bioactive material groups revealed that a significantly higher proportion of animals in the bioactive glass group exhibited moderate or severe inflammation (80 vs. 20%; p = 0.002814). CONCLUSION: Periosteal flaps prefabricated with hydroxyapatite or bioactive glass in rats exhibit osteogenic capacities that are not dependent on direct bone contact or proximity to vascular bony tissue. The innate capacity of the periosteal flap when utilized alone for osteoneogenesis was found to be rather insufficient.

WITHDRAWN: Riluzole alleviates early neutrophil infiltration, brain oedema and lipid peroxidation in the traumatic brain tissue but does not induce neurotoxicity in non-traumatic brain tissue in rats.

This article has been withdrawn at the request of the editor since, in breach of ethical guidelines and journal policies, the manuscript was submitted without the full knowledge and consent of all authors listed. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

Prophylactic feeding with immune-enhanced diet ameliorates chemoradiation-induced gastrointestinal injury in rats.

PURPOSE: To investigate the protective effect of immune-enhanced diet (IED) on chemoradiation-induced injury of the gastrointestinal mucosa. MATERIALS AND METHODS: Forty-eight Sprague-Dawley rats were divided into control (C, n=6), irradiation (IR, n=14), fluoropyrimidine (5-FU, n=14)-treated, IR + 5-FU (n=14)-treated groups. Half of each irradiated and/or 5-FU-treated groups were previously fed with IED containing arginine, omega-3-fatty acids and RNA fragments, while the other half were fed a standard rat diet (SD) for eight days before the induction of IR or injection of 5-FU. In IR groups, whole abdominal irradiation (11 Gy) was performed with 6 MV photons. In the 5-FU groups, fluoropyrimidine (100 mg/kg) was administered intraperitoneally 30 min prior to irradiation. All animals were sacrificed on the 4th day of IR or 5-FU injection. RESULTS: Bacterial colony counts in the ceca and mesenteric lymph nodes of IED-fed rats, which have received either 5-FU and/or irradiation were significantly lower than the corresponding SD-fed groups. Morphometric results revealed that gastric, ileal and colonic injuries were less in IED-treated IR or IR + 5-FU + IED groups, as compared to SD-fed groups. However, IED did not alter DNA fragmentation ratios. CONCLUSION: Prophylactic feeding of IED has a protective effect on chemoradiation-induced gastrointestinal injury, which appears to involve the eradication of bacterial overgrowth.

Halofuginone has a beneficial effect on gentamicin-induced acute nephrotoxicity in rats.

The aim of this study was to investigate the putative beneficial effect of halofuginone on gentamicin-induced nephrotoxicity in rats. Sprague-Dawley rats were treated with gentamicin sulphate (GEN; 80 mg/kg) or saline intraperitoneally (i.p.) for 7 days. Halofuginone was administered (0.1 mg/kg/day; i.p.) following GEN or saline injections. Blood and urine samples were collected to measure the renal function tests. Kidneys were excised for histological evaluation and for the measurement of malondialdehyde (MDA), glutathione (GSH), myeloperoxidase (MPO) activity, and chemiluminescence (CL). Halofuginone treatment to animals with GEN-induced renal injury caused a significant decrease in serum blood urea nitrogen level and reduced the elevated MDA, GSH content, and MPO activity. It was also effective in reversing the elevated CL values of rats with GEN-induced nephrotoxicity and preserving renal morphology, as examined microscopically. In conclusion, halofuginone was beneficial in GEN-induced acute nephrotoxicity. The mechanism could be attributed, at least in part, to decreased tissue leukocyte infiltration and reactive metabolite production.

Comparison of regeneration results of prefabricated nerve graft, autogenous nerve graft, and vein graft in repair of nerve defects.

The purpose of this study was to evaluate the effectivity of prefabricated nerve grafts in the repairing nerve defect and to compare them with the autogenous nerve graft and vein graft. Four groups were created, each containing 10 rats. First, nerve prefabrication was carried out in groups I and II during 8 weeks. For this purpose, jugular vein graft was sutured to the epineural windows on the peroneal and tibial nerve at the right side in an end-to-side fashion. To create neurotrophic stimulus, partial incision was performed on the nerves in group I, and gene therapy was performed by plasmid injecting to the adjacent muscles in group II. At the end of the eighth week, prefabricated nerve grafts, jugular vein, and the axons passing through it were taken. Then, gap was created on the left peroneal nerve in all groups. Defect on the peroneal nerve was repaired by using the prefabricated nerve grafts in groups I and II, the autogenous nerve graft in group III, and the vein in group IV. Assessment of nerve regeneration was performed by using electromyography. Morphological assessment was performed after follow-up period. According to electrophysiological and morphological results, the results of first three groups were similar. There was no statistically significant difference between three groups. Prefabricated nerve graft is as effective as autogenous nerve graft, and it can be used in the repair of nerve defects as autogenous nerve graft as an alternative.

Nerve graft prefabrication: preliminary study.

This study aimed to produce prefabricated nerve graft as effective as autologous nerve graft without donor site morbidity for repairing segmental nerve defects. Thirty rats were used and were separated into three groups. In the first group, vein graft excised from jugular vein was sutured to make a bridge between epineural gaps of tibial and peroneal nerve. In the second group, one-quarter of the nerve diameter was incised after excision of the epineurial sheath, and the vein graft was sutured between epineurial gaps. In the third group, the vein graft was sutured between epineurial gaps, and plasmid including vascular endothelial growth factor (VEGF) gene were injected into muscle next to the nerve. Functional and morphological assessments were performed at the end of the 8 weeks. We prefabricated nerve graft by using autologous vein as a conduit material between two intact nerves and by gene therapy, which increases the VEGF level in the medium.

Electrokinetic and adsorption properties of sepiolite modified by 3-aminopropyltriethoxysilane.

Surface modification of clay minerals has become increasingly important for improving the practical applications of clays such as fillers and adsorbents. An investigation was carried out on the surface modification of sepiolite with aminopropylsilyl groups in 3-aminopropyltriethoxysilane (3-APT). The zeta potential of the modified sepiolite suspensions was measured as a function of initial electrolyte concentration and equilibrium pH using a Zeta Meter 3.0 for modified sepiolite. The utility of the 3-APT-modified sepiolite was investigated as an adsorbent for removal of various heavy metal ions such as Fe, Mn, Co, Zn, Cu, Cd and Ni from aqueous solutions. The effects of various factors on the adsorption, such as pH, ionic strength and temperature of the solution were studied. The results showed that the amount adsorbed increases with solution pH in the pH range of 1.5 and 7.0; indicated that the modified sepiolite adsorbed Fe and Mn ions more than other metal ions such as Co, Zn, Cu, Cd and Ni. It was found that the temperature had an important effect on metal ion adsorption by the modified sepiolite. The adsorption isotherm has been determined and data have been analyzed according to the Langmuir and Freundlich models.

Uptake of trivalent chromium ions from aqueous solutions using kaolinite.

The sorption of Cr(III) from aqueous solutions on kaolinite has been studied by a batch technique. We have investigated how solution pH, ionic strength and temperature affect this process. The adsorbed amount of chromium ions on kaolinite has increased with increasing pH and temperature when it has decreased with increasing ionic strength. The sorption of Cr(III) on kaolinite is endothermic process in nature. Sorption data have been interpreted in terms of Freundlich and Langmuir equations. The adsorption isotherm was measured experimentally at different conditions, and the experimental data were correlated reasonably well by the adsorption isotherm of the Langmuir, and the isotherm parameters (q(m) and K) have been calculated as well. The enthalpy change for chromium adsorption has been estimated as 7.0 kJ mol(-1). The order of enthalpy of adsorption corresponds to a physical reaction.

Purification and characterization of Ocimum basilicum L. polyphenol oxidase.

A partial characterization of polyphenol oxidase (PPO) activity in Ocimum basilicum L. is described. PPO in O. basilicum L. was extracted and purified through (NH4)2SO4 precipitation, dialysis, and a Sepharose 4B-l-tyrosine-p-aminobenzoic acid affinity column. The samples obtained from (NH4)2SO4 precipitation and dialysis were used for the characterization of PPO. At the end of purification by affinity chromatography, 11.5-fold purification was achived. The purified enzyme exhibited a clear single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular mass of the enzyme was estimated to be approximately 54 kDa. The contents of total phenolic and protein of O. basilicum L. extracts were determined. The total phenolic content of O. basilicum L. was determined spectrophotometrically according to the Folin-Ciocalteu procedure and was found to be 280 mg 100 g(-1) on a fresh weight basis. The protein content was determined according to the Bradford method. The enzyme showed activity to 4-methylcatechol, catechol, and pyrogallol substrates, but not to tyrosine. Therefore, of these three substrates, 4-methylcatecol was the best substrate due to the highest V(max)/K(m) value, followed by pyrogallol and catechol. The optimum pH was at 6, 8, and 9 for 4-methylcatechol, catechol, and pyrogallol, respectively. The enzyme had an optimum temperature of 20, 40, and 50 degrees C for 4-methylcatechol, catechol, and pyrogallol, respectively. It was found that optimum temperature and pH were dependent on the substrates studied. The enzyme activity with increasing temperature and inactivation time for 4-methylcatechol, catechol, and pyrogallol substrates decreased due to heat denaturation of the enzyme.