[Effects of prophylactic chemotherapy on outcomes and prognosis of patients older than 40 years with invasive mole]

Objective: To discuss the effects of prophylactic chemotherapy on the outcomes and prognosis of invasive mole patients. Methods: One hundred and fifteen invasive mole (IM) patients older than 40 years were registered in Peking Union Medical Collage Hospital.Eleven of them were treated with prophylactic chemotherapy before diagnosed as IM prophylactic chemotherapy group, while the other 104 cases received therapeutic chemotherapy after diagnosed as IM (non-prophylactic chemotherapy group). The general clinical data (including age, clinical stage, risk factor score), treatment, outcomes and relapse of patients were retrospectively compared between two groups. Results: (1) The age of prophylactic chemotherapy group and non-prophylactic chemotherapy group were (47±5) versus (46±4) years old. Ratio of clinical stageⅠ-Ⅱ were 3/11 versus 29.8% (31/104), clinical stage Ⅲ-Ⅳ were 8/11 versus 70.2% (73/104). Ratio of risk factor score 0-6 were 11/11 versus 84.6% (88/104), risk factor score >6 were 0 versus 15.4% (16/104). There were no significant statistical differences between two groups in age, clinical stage or risk factor score (all P>0.05). (2) Treatment: the total chemotherapy courses between prophylactic chemotherapy group and non-prophylactic chemotherapy group (median 7 versus 5) were significantly different (Z=3.071,P=0.002). There were no significant statistical differences between two groups in the chemotherapy courses until negative conversion of β-hCG, consolidation chemotherapy courses, total therapeutic chemotherapy courses or ratio of hysterectomy (all P>0.05). (3) Outcomes and relapse: between the prophylactic chemotherapy group and the non-prophylactic chemotherapy group, the complete remission rate were 11/11 versus 98.1%(102/104), the relapse rate were 0 versus 1.0%(1/102). There were no significant difference between the two groups in outcomes or relapse rate (P>0.05). Conclusions: Prophylactic chemotherapy does not substantially benefit the IM patients older than 40 years. Prophylactic chemotherapy may not significantly improve patients' prognosis, in which increased sample size is required in further study.

[LB100 reverses the acquired resistance to gefitinib in lung adenocarcinoma cells with EGFR mutation]

Objective: To investigate the possibility of the Protein Phosphatase 2A (PP2A) inhibitor, LB100, in reversing acquired resistance to gefitinib in lung adenocarcinoma with epidermal growth factor receptor (EGFR) gene mutation. Methods: Cell line NCI-H1975 and established primary culture cell line 44-1 with gefitinib resistance were sequenced to determine the mutation type of EGFR gene. Cells were treated with gefitinib alone or combined with LB100 to determine the half maximal inhibitory concentration (IC50), and sensitivity of 44-1 and NCI-1975 to gefitinib alone or combined with LB100 was compared. The volume of NCI-H1975 xenografts with different drug treatments was observed to determine the efficiency of gefitinib with or without LB100 in tumor growth inhibition. Results: Both 44-1 and NCI-1975 cells had double EGFR mutation (sensitive L858R mutation and resistant T790M mutation). Both cells showed significant gefitinib resistance (IC50: 23.0 μmol/L in 44-1, 16.7 μmol/L in NCI-1975). When combined with LB100, IC50 of gefitinib decreased to 6.9 μmol/L in 44-1 cell and decreased to 3.4 μmol/L in NCI-H1975 cells. In NCI-1975 xenografts experiments, LB100 enhanced the ability of gefitinib in tumor growth inhibition (P<0.05). Conclusion: LB100 reverses acquired resistance to gefitinib in lung adenocarcinoma cell lines.

Blockade of Interleukin-17 Restrains the Development of Acute Lung Injury

The acute respiratory distress syndrome (ARDS), a clinical complication of severe acute lung injury (ALI) in humans, is a leading cause of morbidity and mortality in critically ill patients. Here, we explored the association between IL-17 and development of ALI using LPS-induced murine model. We found that IL-17 level was elevated in bronchoalveolar lavage (BAL) fluid of ALI mice. Upregulation of IL-17 resulted in increased severity of ALI as evidenced by decreased body weight and survival rate, elevated level of total protein and albumin in BAL fluid, as well as more apparent histopathology changes of lung. Induction of ALI was impaired in IL-17-deficient mice. Management of IL-17 could modulate LPS-induced pulmonary inflammation, as reflected by the total cell and neutrophil counts, proinflammatory cytokines, as well as chemokines in BAL fluid. Of note, blockade of IL-17 effectively inhibited the lung inflammation and alleviated ALI severity. Finally, we confirmed the clinical relevance and found that IL-17 expression was elevated and associated with the disease severity in patients with ARDS. In essence, IL-17 was crucial for development of ALI, suggesting a potential application for IL-17-based therapy in clinical practice.

Deep roots and soil structure

In this opinion article we examine the relationship between penetrometer resistance and soil depth in the field. Assuming that root growth is inhibited at penetrometer resistances > 2.5 MPa, we conclude that in most circumstances the increases in penetrometer resistance with depth are sufficiently great to confine most deep roots to elongating in existing structural pores. We suggest that deep rooting is more likely related to the interaction between root architecture and soil structure than it is to the ability of a root to deform strong soil. Although the ability of roots to deform strong soil is an important trait, we propose it is more closely related to root exploration of surface layers than deep rooting.

Kinetic analysis of RNA editing of Newcastle disease virus P gene in the early period of infection

As a paramyxovirus, Newcastle disease virus (NDV) has the ability to edit its P (phosphoprotein) gene to synthesize three kinds of viral protein (P, V and W). It is technically very difficult to differentiate P, V and W mRNAs, and little was known about NDV regulation of RNA-editing frequency. To investigate the rules of NDV RNA editing, the ratio of the P gene-derived transcripts (P, V and W) was determined by sequencing at different time points post-infection. The results showed unstable ratio of V and W mRNA at different time points, and the frequency of NDV editing was significantly increased at the early period of infection (P 

KEYWORDS

Newcastle disease virus; phosphoprotein; RNA editing; G insertion.

Non-volatile memory devices with redox-active diruthenium molecular compound

Reduction-oxidation (redox) active molecules hold potential for memory devices due to their many unique properties. We report the use of a novel diruthenium-based redox molecule incorporated into a non-volatile Flash-based memory device architecture. The memory capacitor device structure consists of a Pd/Al2O3/molecule/SiO2/Si structure. The bulky ruthenium redox molecule is attached to the surface by using a 'click' reaction and the monolayer structure is characterized by x-ray photoelectron spectroscopy to verify the Ru attachment and molecular density. The 'click' reaction is particularly advantageous for memory applications because of (1) ease of chemical design and synthesis, and (2) provides an additional spatial barrier between the oxide/silicon to the diruthenium molecule. Ultraviolet photoelectron spectroscopy data identified the energy of the electronic levels of the surface before and after surface modification. The molecular memory devices display an unsaturated charge storage window attributed to the intrinsic properties of the redox-active molecule. Our findings demonstrate the strengths and challenges with integrating molecular layers within solid-state devices, which will influence the future design of molecular memory devices.

Analysis of Th17-associated cytokines in tears of patients with dry eye syndrome

PURPOSE

To determine the levels of Th17-associated cytokines, particularly interleukin (IL)-17 and IL-22 in tears of patients with dry eye syndrome.

METHODS

Tear samples were collected from 20 healthy volunteers, 20 dry eye (DE) patients with non-Sjögren's syndrome (NSSDE) and 20 DE patients with Sjögren's syndrome (SSDE). Symptom questionnaire was self-administered and multiple dry eye disease (DED)-related clinical tests were performed. The levels of IL-17 and IL-22 in tears were measured by enzyme-linked immunosorbent assay.

RESULTS

The levels of IL-17 and IL-22 were significantly increased in tears of DE patients compared with those of controls and also higher in SSDE patients compared with those of NSSDE patients (P<0.05). Moreover, the levels of IL-17 and IL-22 were positively correlated with questionnaire score and keratopathy score but negatively correlated with tear film break-up time and Schirmer I test in both NSSDE and SSDE patients (P<0.05).

CONCLUSIONS

The levels of IL-17 and IL-22 in tears were significantly increased in DE patients, which were associated with the disease severity. Therefore, Th17 cell-associated cytokines, particularly IL-17 and IL-22, may have important roles in the immunopathogenesis of the DED.

HTLV-1 Tax deregulates autophagy by recruiting autophagic molecules into lipid raft microdomains

The retroviral oncoprotein Tax from Human T cell leukemia virus type 1 (HTLV-1), an etiological factor that causes adult T cell leukemia and lymphoma, plays a crucial role in initiating T lymphocyte transformation by inducing oncogenic signaling activation. We here report that Tax is a determining factor for dysregulation of autophagy in HTLV-1-transformed T cells and Tax-immortalized CD4 memory T cells. Tax facilitated autophagic process by activating IκB kinase complex, which subsequently recruited an autophagy molecular complex containing Beclin1 and Bif-1 to the lipid raft microdomains. Tax engaged a crosstalk between IκB kinase complex and autophagic molecule complex by directly interacting with both complexes, promoting assembly of LC3+ autophagosomes. Moreover, expression of lipid raft-targeted Bif-1 or Beclin1 was sufficient to induce formation of LC3+ autophagosomes, suggesting that Tax recruitment of autophagic molecules to lipid rafts is a dominant strategy to deregulate autophagy in the context of HTLV-1 transformation of T cells. Furthermore, depletion of autophagy molecules such as Beclin1 and PI3 kinase class III resulted in impaired growth of HTLV-1-transformed T cells, indicating a critical role of Tax-deregulated autophagy in promoting survival and transformation of virally infected T cells.

Molecular cloning, characterization, and expression analysis of the Muscovy duck Toll-like receptor 3 (MdTLR3) gene

Toll-like receptor 3 (TLR3) is an important membrane-bound receptor for recognizing double-stranded RNA in innate immunity. In this study, we described the cloning and characterization of the Muscovy duck TLR3 (MdTLR3) gene. The full-length MdTLR3 cDNA (2,836 bp) encoded a polypeptide of 895 amino acids. The deduced amino acid sequence contained 4 main structural domains: a signal peptide, an extracellular leucine rich repeats domain, a transmembrane domain, and a Toll/IL-1 receptor domain. Quantitative real-time PCR analysis indicated that MdTLR3 mRNA was constitutively expressed in all sampled tissues of uninfected Muscovy duck except muscle. Expression of MdTLR3 in brain was significantly upregulated at 24 h (1.94-fold, P < 0.05), reached a peak at 48 h (4.64-fold, P < 0.05), and recovered to normal levels at 72 h postinfection with the H5N1 highly pathogenic avian influenza virus. In contrast, MdTLR3 expression was downregulated during the test period in spleen and lung. These results implicated MdTLR3 was a novel member of the TLR family, which is involved in the early stage of antiviral innate immunity.

Acidic Biopolymers as Dispersants for Ceramic Processing

Some acidic biopolymers serve as dispersants for colloidal processing of ceramics. One biopolymer we tested was alginate, a heteropolysaccharide containing two carboxylic sugar acids, D-mannuronic and D-guluronic. Kelp alginate was a suitable dispersant, provided that its viscosity was reduced by partial acid hydrolysis. Low molecular weight polymers rich in guluronic acid proved to be better dispersants than those rich in mannuronic acid, perhaps due to their greater charge density caused by their buckled molecular configuration. In situ processing of ceramic materials was tested by growing the alginate-producing bacterium, Azotobacter vinelandii, in the presence of alumina particles. Growth occurred at 15 vol% alumina in medium. Alumina particles which were exposed to such treatment showed a high packing density comparable to that with purified polymer. We also tested polypeptide polymers of the dicarboxylic amino acids, glutamate and aspartate, which also served as excellent dispersants for small alumina particles.

Spontaneous basilar membrane oscillation and otoacoustic emission at 15 kHz in a guinea pig

A spontaneous otoacoustic emission (SOAE) measured in the ear canal of a guinea pig was found to have a counterpart in spontaneous mechanical vibration of the basilar membrane (BM). A spontaneous 15-kHz BM velocity signal was measured from the 18-kHz tonotopic location and had a level close to that evoked by a 14-kHz, 15-dB SPL tone given to the ear. Lower-frequency pure-tone acoustic excitation was found to reduce the spontaneous BM oscillation (SBMO) while higher-frequency sound could entrain the SBMO. Octave-band noise centered near the emission frequency showed an increased narrow-band response in that frequency range. Applied pulses of current enhanced or suppressed the oscillation, depending on polarity of the current. The compound action potential (CAP) audiogram demonstrated a frequency-specific loss at 8 and 12 kHz in this animal. We conclude that a relatively high-frequency spontaneous oscillation of 15 kHz originated near the 15-kHz tonotopic place and appeared at the measured BM location as a mechanical oscillation. The oscillation gave rise to a SOAE in the ear canal. Electric current can modulate level and frequency of the otoacoustic emission in a pattern similar to that for the observed mechanical oscillation of the BM.

Genetic characterization of H5N1 avian influenza viruses isolated in southern China during the 2003–04 avian influenza outbreaks

The recent H5N1 avian influenza outbreaks in Asia spread over more than 8 countries. It has caused enormous economic loss and grand challenges for the public health. During these breakouts we isolated three strains of H5N1 Avian Influenza Virus (AIV) from chickens and one from duck in different farms of Southern China. We completely sequenced these four AIVs. Molecular characterization demonstrated that these strains retain the reported H5N1 AIV sequence properties relevant to virus virulence and host adaptation. Phylogeny results demonstrated that three of these isolates (except A/Chicken/Guangdong/174/04) were closely linked to other H5N1 AIVs isolated from the recent H5N1 outbreaks in Asia. Six of 8 segments (except PA and M) of A/Chicken/Guangdong/174/04 also shares a close linkage to other H5N1 AIVs isolated from the recent H5N1 outbreaks. However, the PA gene of A/Chicken/Guangdong/174/04 and another H5N1 strain forms a distinct subgroup along with an H6N1 AIV, and the M gene of A/Chicken/Guangdong/174/04 shows a close linkage to some H5N1 AIVs from aquatic species in China. Our findings suggest that a new genotype of AIV (in addition to previous reported ones) was present during the 2003-04 Asian bird flu outbreaks and that continuing virus surveillance of AIVs be conducted to monitor the evolutionary paths of the A/Chicken/Guangdong/174/04-like AIVs.

Mechanisms regulating the development of the corpus callosum and its agenesis in mouse and human

The development of the corpus callosum depends on a large number of different cellular and molecular mechanisms. These include the formation of midline glial populations, and the expression of specific molecules required to guide callosal axons as they cross the midline. An additional mechanism used by callosal axons from neurons in the neocortex is to grow within the pathway formed by pioneering axons derived from neurons in the cingulate cortex. Data in humans and in mice suggest the possibility that different mechanisms may regulate the development of the corpus callosum across its rostrocaudal and dorsoventral axes. The complex developmental processes required for formation of the corpus callosum may provide some insight into why such a large number of human congenital syndromes are associated with agenesis of this structure.

Synthesis of galactosyl compounds for targeted gene delivery

Cell-specific DNA delivery offers a great potential for targeted gene therapy. Toward this end, we have synthesized a series of compounds carrying galactose residues as a targeting ligand for asialoglycoprotein receptors of hepatocytes and primary amine groups as a functional domain for DNA binding. Biological activity of these galactosyl compounds in DNA delivery was evaluated in HepG2 and BL-6 cells and compared with respect to the number of galactose residues as well as primary amine groups in each molecule. Transfection experiments using a firefly luciferase gene as a reporter revealed that compounds with multivalent binding properties were more active in DNA delivery. An optimal transfection activity in HepG2 cells requires seven primary amine groups and a minimum of two galactose residues in each molecule. The transfection activity of compounds carrying multi-galactose residues can be inhibited by asialofetuin, a natural substrate for asialoglycoprotein receptors of hepatocytes, suggesting that gene transfer by these galactosyl compounds is asialoglycoprotein receptor-mediated. These results provide direct evidence in support of our new strategy for the use of small and synthetic compounds for cell specific and targeted gene delivery.

Increased Bcl-w expression following focally evoked limbic seizures in the rat

Control of seizure-induced neuronal death may involve members of the Bcl-2 family of cell death regulating proteins. Bcl-w is a newly described anti-apoptotic member of this family that may confer neuroprotective effects. We therefore investigated Bcl-w expression in rat brain following focally evoked limbic seizures. Seizures were induced by unilateral microinjection of kainic acid into the amygdala of the rat and terminated after 40 min by diazepam. Constitutive Bcl-w expression was detected by Western blotting and immunohistochemistry. Bcl-w expression was increased 4-72 h following seizures within the injured hippocampus. Immunohistochemistry determined Bcl-w was predominantly expressed in neurons and seizures increased Bcl-w immunoreactivity within piriform cortex and surviving regions of the injured hippocampus. These data suggest Bcl-w may be involved in the modulation of seizure-induced brain injury.

Expanding Cavitand Chemistry: The Preparation and Characterization of [n]Cavitands withn≥4

The preparation of cavitands composed of 4, 5, 6, and 7 aromatic subunits ([n]cavitands, n=4-7) is described. The simple, two-step synthetic procedure utilized readily available starting materials (2-methylresorcinol and diethoxymethane). The two cavitand products having 4 and 5 aromatic subunits exhibited highly symmetric cone conformations, while the larger cavitands (n = 6 and 7) adopt conformations of lower symmetry. 1H NMR spectroscopic studies of [6]cavitand and [7]cavitand revealed that these hosts undergo exchange between equivalent conformations at room temperature. The departure of these two cavitands from cone conformations is related to steric crowding on their Ar-O-CH2-OAr bridges and is predicted by simple molecular mechanics calculations (MM2 force field). X-ray diffraction studies on single crystals of the [4]cavitand, [5]cavitand, and [6]cavitand hosts afforded additional experimental support for these conclusions.

Quinine-induced alterations of electrically evoked otoacoustic emissions and cochlear potentials in guinea pigs

Quinine is a well-known ototoxic drug which may affect portions of the auditory system with different biochemical effects, causing reversible hearing loss and tinnitus. Recent investigations indicate that quinine at high concentrations can act directly on cochlear outer hair cells to affect their motility and the mechanical response of the basilar membrane. This study aimed to investigate the effect of quinine on the electromotility of outer hair cells in vivo by means of measuring the electrically evoked otoacoustic emissions (EEOAEs), and the relationship between EEOAE and hearing sensitivity alterations in guinea pigs. Quinine was infused into the scala tympani with concentrations between 0.05 and 5 mM. An alternating current (35 microA RMS) swept from 400 Hz to 40 kHz was applied to the round window to evoke the EEOAE. The compound action potential (CAP), cochlear microphonic (CM) and summating potential (SP) were also measured. Results show that quinine affects the EEOAE in a dose-dependent manner and that its effects are reversible. Two aspects of the EEOAE were affected by quinine, depending on concentration: (1) the 'fine structure' only for concentrations below 0.1 mM and (2) the overall amplitude and the 'fine structure' for concentrations above 0.1 mM. At 5 mM the fine structure was completely absent and the mean amplitude of the EEOAE greatly decreased. Multiple component analysis shows the short delay component of the EEOAE is related to the mean value of the amplitude spectrum while the long delay component is related to the fine structure. The alterations of the EEOAE are roughly comparable to that of the cochlear potentials. A 'threshold concentration' for quinine's effects was found at 25 microM. CAP was significantly affected at 25 microM while EEOAE, CM and SP were not. Enhancement of the EEOAE amplitude was noticed in five out of 20 animals in the current study. The enhancement appears only related to the EEOAE mean level or short delay component. The results suggest that quinine can affect in vivo electromotility of outer hair cells at low concentration and therefore change the cochlear amplifier performance via an effect on electro-mechanical transduction. Its effects on the cochlear spiral ganglion neurons and/or their presynaptic process are also suggested, and these are speculated to be the primary sites for quinine's effects on the auditory system.

Nitric oxide distribution and production in the guinea pig cochlea

Production sites and distribution of nitric oxide (NO) were detected in cochlear lateral wall tissue, the organ of Corti and in isolated outer hair cells (OHCs) from the guinea pig using the fluorescent dye, 4,5-diaminofluorescein diacetate. Fluorescent signal, indicating the presence of NO, was found in the afferent nerves and their putative endings near inner hair cells (IHCs) and putative efferent nerve endings near OHCs, the IHCs and OHCs, the endothelial cells of blood vessels of the spiral ligament, the stria vascularis, and the spiral blood vessels of the basilar membrane. An increased NO signal was observed following exposure to the substrate for NO, L-arginine, while exposure to NO synthase inhibitors resulted in a decrease in NO signal. Observation of OHCs at the subcellular level revealed differentially strong fluorescent signals at the locations of cuticular plate, the subcuticular plate region, the infranuclear region, and the region adjacent to the lateral wall. The findings indicate the presence of NO in the cochlea and suggest that NO may play an important role in both regulating vascular tone and mediating neurotransmission in guinea pig cochlea.

Recording depth of the heterodyne laser interferometer for cochlear vibration measurement

Measurement of the cochlear partition vibration as a function of the optical-axis (z-axis) position in the gerbil cochlea showed that the velocity distributes over a range of more than 300 microm, which is larger than the thickness of the cochlear partition. This finding suggests that the recording depth (RD) of the heterodyne interferometer probably is not as small as reported in the literature. In the current experiment, the RD of the heterodyne laser interferometer was studied by measuring the velocity of a vibrating mirror as a function of the z-axis position. Results demonstrate that the optical sectioning characteristic, measured by the intensity of the reflected laser beam as a function of the z-axis position, is not able to correctly estimate the RD of the heterodyne interferometer: the RD is much larger than optical sectioning, indicating a poor spatial resolution along the z axis.

Electrically evoked otoacoustic emissions from apical and basal perilymphatic electrode positions in the guinea pig cochlea

Stimulation of the cochlea with sinusoidal current results in the production of an otoacoustic emission at the primary frequency of the stimulus current. In this study we test the hypothesis that the wide frequency response from round window (RW) stimulation is due to the involvement of a relatively large spatial segment of the organ of Corti. Tonotopically organized group delays would be evident from perilymphatic electrode locations that restrict the spatial extent of hair cell stimulation. Monopolar and bipolar-paired stimulus electrodes were placed in perilymphatic areas of the first or third cochlear turns and the electrically evoked otoacoustic emissions (EEOAE) produced by these electrodes were compared to that from the RW monopolar electrode in the anesthetized guinea pig. Current stimuli of 35 microA RMS were swept across the frequency range between 60 Hz and 100 kHz. The EEOAE was measured using a microphone coupled to the ear canal. It was found that the bandwidth of EEOAEs from RW stimulation extended to at least 40 kHz and was a relatively insensitive to electrode location on the RW. The group delay of the EEOAE from stimulation at the RW membrane (corrected to stapes motion) was about 53 micros. First and third turn stimulations from electrode placements in perilymph near the bony wall of cochlea yielded narrower band EEOAE magnitude spectra but which had the same short group delays as for RW stimulation. A confined current (from a bipolar electrode pair) applied close to the basilar membrane (BM) in the first turn produced the narrowest frequency-band magnitude emissions and a mean corrected group delay of 176 micros for a location approximately 3 mm from the high frequency end of the BM (corresponding to about the 18 kHz best frequency location). Bipolar electrodes in the third turn scala tympani produced low pass EEOAE magnitude functions with corrected group delays ranging between approximately 0.3 and 1 ms. The average phase slopes did not change with altered cochlear sensitivity and postmortem. These data indicate that the EEOAE from RW stimulation is the summed response from a wide-tonotopic distribution of outer hair cells. A preliminary model study indicates that short time delayed emissions are the result of a large spatial distribution of current applied to perilymphatic locations possibly giving rise to "wave-fixed" emissions.

Basilar membrane vibration in the basal turn of the sensitive gerbil cochlea

The basal membrane (BM) velocity responses to pure tones were measured using a newly developed laser interferometer microscope that does not require placing a reflecting object on the BM. It was demonstrated that the instrument is able to measure sub-nanometer vibration from the cochlear partition in the basal turn of the gerbil. The overall shape of the amplitude spectra shows typical tuning features. The 'best' frequencies (BFs) for the BM locations studied were between 14 kHz and 27 kHz, depending on the longitudinal position. For a given BM location, tuning sharpness was input level dependent, indicated by the Q(10dB), which varied from approximately 3 at low stimulus levels to near 1.5 at high input levels. At frequencies below BF, parallel amplitude/frequency curves across stimulus levels indicate a linear growth function. However, at frequencies near BF, the velocity increased linearly at low levels (<40 dB SPL) and became compressed between 40 and 50 dB SPL. Although the velocity gain for the frequency range below BF was a function of frequency, for a given frequency the gains were approximately constant across different levels. At frequencies near BF, the velocity gain at low sound pressure level was greater than that at a high sound pressure level, indicating a nonlinear negative relationship to stimulus level. The data also showed that the BF shifts toward the low frequencies with stimulus intensity increase. The phase spectra showed two important features: (1) at frequencies about half octave below the BF, phase slope is very small, indicating an extremely short delay; (2) the greatest phase lag occurs at frequencies near the BF, indicating a significant delay near this frequency range.

Effect of ligustrazine on hematopoiesis in bone marrow transplantation mice

The effect of Ligustrazine on the hematopoiesis after bone marrow transplantation (BMT) in allogenic BMT mice was investigated. After the typical mice model of allogenic BMT had been established, the mice were randomly divided into three groups: BMT group, Ligustrazine group and normal group. The BMT group was given normal saline (0.2 ml, twice a day) through gastric tube, while the Ligustrazine group was given Ligustrazine through gastric tube (0.2 ml, twice a day). At the 1st, 7th and 14th day after BMT, we observed the peripheral blood cells and bone marrow nuclear cells (BMNC), as well as the expression level of Heparan Sulfate (HS) and stromal cell derived factor-1 (SDF-1) on bone marrow sections by using immunohistochemistry (SABC-AP), the expression of CXCR4 on the BMNC. The results showed that on the 7th and 14th day, the peripheral blood white cells, platelets, BMNC and the expression levels of CXCR4, HS and SDF-1 were significantly higher in Ligustrazine group than in the BMT group (P < 0.05). It was concluded that Ligustrazine could promote hematopoiesis at the early stage of hematopoietic reconstitution after BMT.

HRT gene function requires interaction between a NAC protein and viral capsid protein to confer resistance to turnip crinkle virus

An Arabidopsis protein was found to interact specifically with the capsid protein (CP) of turnip crinkle virus (TCV) through yeast two-hybrid screening. This protein, designated TIP (for TCV-interacting protein), was found to be a member of the recently recognized NAC family of proteins. NAC proteins have been implicated in the regulation of development of plant embryos and flowers. TIP alone was able to activate expression of reporter genes in yeast if fused to a DNA binding domain, suggesting that it may be a transcriptional activator. The TIP binding region in the TCV CP has been mapped to the N-terminal 25 amino acids. Site-directed mutagenesis within this region revealed that loss of the TIP-CP interaction in the yeast two-hybrid assay correlated with loss of the ability of TCV to induce the hypersensitive response and resistance in the TCV-resistant Arabidopsis ecotype Dijon (Di-0 and its inbred line Di-17). These data suggest that TIP is an essential component in the TCV resistance response pathway.

Production and consumption of nitric oxide by three methanotrophic bacteria

We studied nitrogen oxide production and consumption by methanotrophs Methylobacter luteus (group I), Methylosinus trichosporium OB3b (group II), and an isolate from a hardwood swamp soil, here identified by 16S ribosomal DNA sequencing as Methylobacter sp. strain T20 (group I). All could consume nitric oxide (nitrogen monoxide, NO), and produce small amounts of nitrous oxide (N(2)O). Only Methylobacter strain T20 produced large amounts of NO (>250 parts per million by volume [ppmv] in the headspace) at specific activities of up to 2.0 x 10(-17) mol of NO cell(-1) day(-1), mostly after a culture became O(2) limited. Production of NO by strain T20 occurred mostly in nitrate-containing medium under anaerobic or nearly anaerobic conditions, was inhibited by chlorate, tungstate, and O(2), and required CH(4). Denitrification (methanol-supported N(2)O production from nitrate in the presence of acetylene) could not be detected and thus did not appear to be involved in the production of NO. Furthermore, cd(1) and Cu nitrite reductases, NO reductase, and N(2)O reductase could not be detected by PCR amplification of the nirS, nirK, norB, and nosZ genes, respectively. M. luteus and M. trichosporium produced some NO in ammonium-containing medium under aerobic conditions, likely as a result of methanotrophic nitrification and chemical decomposition of nitrite. For Methylobacter strain T20, arginine did not stimulate NO production under aerobiosis, suggesting that NO synthase was not involved. We conclude that strain T20 causes assimilatory reduction of nitrate to nitrite, which then decomposes chemically to NO. The production of NO by methanotrophs such as Methylobacter strain T20 could be of ecological significance in habitats near aerobic-anaerobic interfaces where fluctuating O(2) and nitrate availability occur.

Fine structure and multicomponents of the electrically evoked otoacoustic emission in gerbil

Like the acoustically evoked distortion product otoacoustic emissions (DPOAE), the amplitude spectrum of the extracochlear electrically evoked otoacoustic emission (EEOAE) also shows peaks and valleys, which are termed the fine structure (FS) of the EEOAE. The hypothesis that the FS of the EEOAE is generated by multiple wave interactions in the cochlea is investigated by examining the relationship between the FS and the multiple-delay components of the EEOAE. The bulla of the gerbil was exposed using a ventral surgical approach. One pole of a bipolar electrode was placed in the round window niche, and the other pole on the surface of the first cochlear turn. A microphone was used to measure electrically evoked sound pressure change in the ear canal. A recently developed multicomponent analysis method was used to detect the EEOAE multiple delays. It was found that the FS is the spectral representation of the multiple-delay components. The relative power of a prominent long delay component (LDC) shows a negative relationship to the electrical stimulus level. Both the FS and the LDC were abolished by intravenous furosemide. Reconstructed signals showed that mathematical removal of the EEOAE LDC also completely eliminated the FS. These data demonstrate that the FS and the EEOAE multicomponents are properties of normal cochlear mechanics in a healthy ear and that the FS is a manifestation of the multicomponents. The findings in this study strongly indicate that the FS of the EEOAE evoked by extracochlear electrical stimulation is generated by wave interaction in the cochlea. The similarity between the EEOAE FS and the DPOAE FS suggests that they may share the same mechanism.

Structural basis of DOTMA for its high intravenous transfection activity in mouse

Eleven structural analogues of two known cationic lipids, N-[1-(2, 3-dioleyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTMA) and N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTAP) were synthesized and utilized to evaluate the structural characteristics of DOTMA for its high intravenous transfection activity. Using a CMV-driven expression system and luciferase gene as a reporter, the transfection activity of these analogues was evaluated in mice using tail vein injection. Results concerning the structure-activity relationship with regard to the influence of the backbone, relative position between head group and the hydrophobic chains on the backbone, linkage bonds, as well as the composition of the aliphatic chains revealed that cationic lipids which give a higher in vivo transfection activity share the following structural characteristics: (1) cationic head group and its neighboring aliphatic chain being in a 1,2-relationship on the backbone; (2) ether bond for bridging the aliphatic chains to the backbone; and (3) paired oleyl chains as the hydrophobic anchor. Cationic lipids without these structural features had lower in vivo transfection activity. These structural characteristics, however, did not significantly influence their in vitro transfection activity. The contribution that cationic lipids make to the overall in vivo transfection activity is likely to be determined by the structure of DNA/lipid complexes and by the outcome of the interaction between the DNA/lipid complexes and blood components upon intravenous administration.

Synthesis and evaluation of vitamin D-based cationic lipids for gene delivery in vitro

A new panel of steroidal cationic lipids has been synthesized for gene delivery. Using commercially available vitamin D2 (calciferol) or vitamin D3 (cholecalciferol) as hydrophobic motifs and a variety of cationic head groups as binding sites for negatively charged phosphate groups in DNA, we demonstrated that the transfection activity of the synthetic vitamin D-based cationic lipids 1d, 2d formulated with dioleoylphosphatidylethanolamine (DOPE) as a co-lipid is comparable to that of 3-(-[N-N',N'-dimethylaminoethane)carbamoyl]cholesterol (DC-Chol). These synthetic lipids are effective in transfecting a variety of cell lines. These results suggest that vitamin D-based cationic lipids are useful transfection reagents for in vitro gene transfer studies.

[Periodontal regeneration by application of the porous beta-TCP/BMP artificial bone to Class II furcation defects]

OBJECTIVE

To study the regeneration of periodontal tissue after the application of beta-TCP/BMP artificial bone to class II furcation defects.

METHODS

Periodontal defects were produced surgically around premolar teeth in 4 dogs. The flap surgery was performed and the root surfaces were curetted to remove the periodontal ligament and the cementum. A synthetic bioabsorble barrier manufactured from poly DL-lactide was used. The defects were divided into 3 groups (beta-TCP/BMP + PDLLA, PDLLA, control). 12 weeks after surgery, the animals were sacrificed and the teeth with their supporting periodontium were processed for light microscopic evaluation.

RESULTS

The definitive evidences of regeneration were founded both in BMP/GTR group and GTR group, but the BMP/GTR group exhibited more new bone formation, cementum deposition occupying the majority of the furcation defects than the other two groups.

CONCLUSION

It was concluded that the beta-TCP/BMP artificial bone can be used in GTR technique to promote periodontal regeneration.

Deltamethrin induces altered expression of P53, Bax and Bcl-2 in rat brain

In this study we investigated the effects of deltamethrin on the expression of P53, Bax and Bcl-2 in rat brain. Immunohistochemical analysis demonstrated that the immunoreactivity for P53 was markedly increased in the cerebral cortex and hippocampus at 5 h after deltamethrin treatment, and maintained at an increased level at 24 and 48 h, whereas little immunoreactivity for P53 was seen in the same brain regions of control rats. The immunostaining for Bax was also elevated in the same brain regions, showing the same time course of P53 expression after deltamethrin treatment. However, the immunolabeling for Bcl-2 was markedly decreased at 24 h after a transient increase at 5 h following deltamethrin treatment. These results indicate that deltamethrin leads to the persistent increase of P53 and Bax expression and transient elevation of Bcl-2 expression, resulting in an increased ratio of Bax to Bcl-2, which may contribute to apoptotic cell death in rat brain following deltamethrin treatment.

[Epidemiological studies on the relationship between body weight and the prevalence rate of impaired glucose tolerance (IGT) in the population of urban areas of Tianjin city]

OBJECTIVE

In order to explore the relationship between body weight and the prevalence rate of IGT in a community - based population and to provide scientific informations of IGT for prevention and control.

METHODS

Cluster sampling was carried out in prevalence survey, together with clinical examination and test of blood plasma glucose.

RESULTS

A sample of 62,577 people was performed by cluster random sampling. Results showed that the crude prevalence rate of IGT in the whole population of three communities was 13.13 per thousand in males, 19.18 per thousand in females, and 16.23 per thousand in both sexes respectively. The IGT prevalence rate of different body weight group in community population had a marked difference. There was a trand that the IGT prevalence rate increased markedly with the increase of body weight.

CONCLUSION

The incidence of IGT is related to body weight and obesity.

Quantitative measure of multicomponents of otoacoustic emissions

A method for quantitatively measuring measuring multicomponents of otoacoustic emissions (OAE) was developed in this study. The method is based on the rationale that, if the acoustic emission is a vector sum of multicomponents coming from different locations in the cochlea, each component will show a delay. The proposed method consists of the following steps: (1) the amplitude and phase of the emission is measured when the emission frequency is swept; (2) the real part of the spectrum is obtained based on the amplitude and phase spectra; and (3) the real part of the emission spectrum is then analyzed using a Fourier transform to extract the multiple components. The theoretical basis and practical procedure of this method are described, and in vitro and in vivo tests are used to demonstrate the validity of the method. Preliminary data demonstrate the multicomponents of the extracochlear electrically evoked otoacoustic emission (EEOAE).

Synthesis and characterization of aromatic ring-based cationic lipids for gene delivery in vitro and in vivo

A new series of cationic lipids has been synthesized for gene delivery using 3,5-dihydroxybenzyl alcohol as the backbone and starting material. Using CMV driven expression system and luciferase gene as a reporter, we demonstrated that the transfection activity of these new lipids when formulated with Tween 80 as co-lipid is comparable to that of DOTAP, one of the most commonly used cationic lipids for transfection. Among the four different cell lines tested including murine melanoma BL-6 cells, human embryonic kidney 293 cells, HepG2 and HeLa cells, the highest transgene expression was seen in 293 cells. Results from in vivo experiments using mice as an animal model show that these cationic lipids preferentially transfect the cells in the lung upon tail vein administration. The cationic lipid, N,N,N-trimethyl-N-[3,5-bis(tetradecyloxy)benzyl] ammonium bromide 4c(di-C14:0) with two 14-hydrocarbon chains exhibits the best transfection activity. These results suggest that these new aromatic ring-based cationic lipids are useful transfection reagents for both in vitro and in vivo gene transfer studies.

Membrane properties and the excitatory junction potentials in smooth muscle cells of cochlear spiral modiolar artery in guinea pigs

Blood circulation changes in the inner ear play an important role in many physiological and pathological conditions of hearing function. The spiral modiolar artery (SMA) is the terminal artery to the cochlea. It was surrounded with nerve fibers immunostained by an antibody for tyrosine hydroxylase. By using intracellular recording techniques on the acutely isolated SMA, membrane properties of the smooth muscle cells and the neuromuscular transmission in this preparation were investigated. With minimum tension and normal extracellular K(+) concentration (5 mM), the majority of muscle cells showed a resting potential near -80 mV and an input resistance of about 8 MOmega. V/I plot showed an inward rectification in these cells. Barium (50-500 microM) caused strong depolarization and an increase in input resistance. Transmural electrical stimulation evoked stimulation intensity-dependent depolarizations (2-31 mV) following a short latency ( approximately 20 ms). The evoked potential by a low intensity stimulus was completely blocked by 1 microM tetrodotoxin. The potential and a depolarization induced by norepinephrine (10 microM) was usually partially (40-90%) blocked by alpha-receptor antagonists prazosin and/or idazoxan with concentrations up to 1 microM. Action potentials were observed when the depolarization was more than -40 mV. It is concluded that SMA smooth muscle cells, similar to those in other brain small arteries, highly express inward rectifying potassium channels; the cells receive catecholaminergic innervation, and stimulation of the nerves elicited an excitatory junction potential that is partially mediated by adrenergic receptors.

Synthesis of diether-linked cationic lipids for gene delivery

Quaternary ammonium lipids 1b-d, with diether linkages between hydrocarbon chains and butane or hexane backbone, were synthesized for cationic liposome-mediated gene delivery. The synthetic strategy of using C-4 or C-6 synthon permits the achievement of the variation of the hydrophobic domain as well as changes of space between the quaternary ammonium head and the hydrophobic domain in the diether-linked cationic lipids.

The radial pattern of basilar membrane motion evoked by electric stimulation of the cochlea

Electric current applied to the cochlea can evoke in situ electromotile responses of the organ of Corti. These nonsound-generated responses can give insight into the mechanics of the organ as the putative forces produced by outer hair cells (OHC) must couple to the modes of vibration of the basilar membrane (BM). In this study, platinum-iridium wire electrodes were positioned into the scala vestibuli and scala tympani of the first cochlear turn in the guinea pig. Current (1.5 ms rectangular-shaped pulses) was applied to these electrodes at levels to 500 microA peak. A laser Doppler velocimeter was used to record the velocity or displacement of the basilar membrane at the tonotopic 18 kHz place via an opening into the scala tympani of the first cochlear turn. Beads were positioned across the width of the BM so that the velocity or displacement of the BM could be studied in the radial direction. It was found that the current pulses evoked linear displacements of up to 2 nm for current levels of 500 microA (higher levels were damaging to the organ of Corti). The pattern of motion across the width of the BM was such that maximum displacement and velocity was located near the first row of OHCs and the position of the outer pillar cell footplate. The BM motion was biphasic in that the zona arcuata moved in the opposite direction to that of the zona pectinata. The results of this study demonstrate that the level of force produced by OHCs is effective in moving the BM and that the distribution of force within the organ of Corti leads to a multimodal motion pattern of the BM for this experimentally artificial means of evoking OHC motion.

[Effect of low dose gamma-irradiation and cigarette smoking on growth and reflex behavior in mice]

Pregnant mice were exposed to different level of gamma-irradiation(60Co 0, 0.25, 0.5 and 1.0 Gy) and water solutions containing different contents of substance from cigarette smoke(0, 0.5, 1.0, 1.5 and 2.0 cigarette/mouse). Results showed that the effect of low dose gamma-irradiation and high concentration cigarette smoke substance could delay the appearance of four physiological markers (eye opening, pinna detachment, hair growth and tooth growth) and the acquisition of four reflexes(surface righting, air righting, virual placing and auditory orienting). A significant combined effect was also observed.

Modification of development by the CFTR gene in utero

The in utero infection of rats at 16-17 days gestation with a recombinant adenovirus carrying the human cystic fibrosis transmembrane conductance regulator (cftr) gene resulted in altered lung development and morphology. These structural alterations prompted an evaluation of concurrent functional changes in the cftr-treated lung. CFTR protein could be detected in treated lungs for up to 30 days postinfection, although it was not detected in the intestines at this time. Increased levels of secreted glycoconjugates and lipids were found in lungs treated in utero with human cftr and large vacuoles containing glycoconjugates were detected within cells of the intestines. The scope and durability of these changes suggested that in utero cftr treatment influenced the activity of secretory cells in the developing lung. Altered secretory products in the lungs of cystic fibrosis patients are thought to be associated with increased susceptibility to Pseudomonas aeruginosa infection. We challenged 3-month-old rats (treated in utero with the human cftr gene) with a lethal, intratrachial dose of this bacteria. Rats treated with cftr exhibited enhanced resistance to Pseudomonas infection when compared to controls. These animals displayed little or no associated inflammatory response. No evidence of the adenovirus transgene was detectable at the time of P. aeruginosa inoculation, indicating that continuous ectopic expression of hcftr was not required for enhanced protection. These data demonstrate that in utero, cftr expression influenced the development and function of cells involved in the primary host defense against bacterial infection in the lung.

Age-related changes in cochlear blood flow response to occlusion of anterior inferior cerebellar artery in mice

Previous studies suggest that autoregulation of cochlear blood flow (CBF) may be impaired by aging. In this study, we quantified the capacity of CBF autoregulation in young adult (6-month-old) and aged (21-month-old) CBA mice, to examine the effect of aging on CBF autoregulation. The technique of anterior inferior cerebellar artery (AICA) occlusion was employed to manipulate cochlear perfusion pressure. The CBF was measured by laser Doppler flowmetry during intermittent occlusion of the AICA with a microvascular clamp, which causes an initial decrease in CBF. The autoregulation of CBF was evaluated by quantifying the CBF increase (compensatory dilatory response in the cochlear vessels) during AICA occlusion. Our results demonstrated that autoregulation of CBF was significantly reduced and that collateral vascular function supplying CBF was significantly lower in the aged group. These findings suggest that the aged ear has less capacity to maintain stable blood flow and thus may be more vulnerable to stress factors that affect cochlear function.

Acoustical modulation of electrically evoked otoacoustic emission in intact gerbil cochlea

In order to study the interaction between mechanical-electrical and electrical-mechanical transductions of outer hair cells (OHCs) in vivo, we observed the acoustically induced changes in the electrically evoked otoacoustic emission (EEOAE). One pole of a bipolar electrode was placed in the round window niche and the other pole on the surface of the first cochlear turn in the gerbil. A microphone and a speaker were used to monitor the EEOAE and to deliver an acoustical tone, respectively. It was found that a high sound level acoustical tone enhanced the EEOAE fine structure at frequencies below the acoustical frequency, and suppressed the overall level of the EEOAE at frequencies above the acoustical frequency. In addition, the EEOAE at frequencies approximately one half octave lower than the acoustical frequencies were relatively more enhanced or showed relatively less suppression than at other frequencies. The amplitudes of these changes had a positive relationship with acoustical tone levels. Furosemide eliminated the acoustically caused EEOAE change indicating that the acoustically caused change in the EEOAE is a phenomenon of the normal cochlea. One possible mechanism for the results is that the electrically and acoustically evoked basilar membrane (BM) vibrations interact at the EEOAE generation site and change the local mechanical and electrical properties. The second possible mechanism is that the acoustical stimulus creates an impedance discontinuity at its characteristic frequency location leading to a change in the reflected electrically evoked traveling wave, which may enhance or suppress the EEOAE by the vector summation of two waves.

Comparative health risk assessment of nuclear power and coal power in China

The public health risk of ionising radiation released from the coal-fired energy chain, 20 deaths (GW a)(-1), is about 18 times that of the nuclear energy chain, 1.1 deaths (GW a)(-1), in China. The main contributors to the fatality risk for the former are the public dose caused by the use of coal ash and the occupational exposure caused by radon and its progeny in coal mines. The total health risk (but excluding low probability/high consequence accidents) of the coal-fired energy chain, 57.1 deaths (GW a)(-1), is about 12 times of that of the nuclear energy chain, 4.6 deaths (GW a)(-1). The health risk of coal-fired energy chain could be significantly reduced if technique and management were improved. Even then the risk of the coal-fired energy chain is about 4.4 times that of the nuclear energy chain.

Basilar membrane velocity noise

Basilar membrane (BM) noise, measured as a velocity signal under the quiet acoustic condition, was investigated in the guinea pig. The cochleas of anesthetized young healthy guinea pigs were surgically exposed and a hole was made on the lateral wall of the scala tympani of the first cochlear turn for visualization of the BM and measurement of the BM velocity with a laser interferometer. The amplitude and frequency of the BM velocity noise were analyzed by a spectrum analyzer under different conditions. The spectrum of the BM velocity noise was a band limited function with a peak velocity at the topographic best frequency of the measured location on the BM. The peak velocity ranged to about 8 microm/s and depended on the physiological condition of the cochlea. Saline blockage of the external auditory canal or the middle ear did not change the BM noise. BM noise was much smaller, or was not evident, when the cochlear sensitivity decreased. The suppression tuning curve of the BM velocity noise indicates that the maximum suppression caused by an acoustic pure tone occurred at the best frequency location. A low sound level wide band acoustic noise given to the external ear canal produced a spectrum function having the same frequency and amplitude response as the BM noise. Electrical stimulation of the crossed olivocochlear bundle significantly depresses the BM velocity noise. These data demonstrate that the BM noise is a representation of internal rather than external noise. The amplitude and frequency of the BM noise reflect the usual cochlear sensitivity and frequency selectivity. Since the organ of Corti in the sensitive cochlea is a highly sensitive and tuned mechanical system, the internal (to the animal) noise responsible for the BM noise may originate from mechanical vibrations remote from the cochlea and propagated to the ear, or may be caused by Brownian motion of cellular structures in the cochlea.

ATP-induced cochlear blood flow changes involve the nitric oxide pathway

Although control mechanisms of cochlear blood flow (CBF) have been intensively studied since laser Doppler flowmetry was introduced for CBF measurement in animals and humans, the role of adenosine 5'-triphosphate (ATP) in CBF regulation is not known. Since ATP is a potent vasoactive agent in other organs, the aim of this study is to examine ATP-induced changes in CBF and to test whether the nitric oxide pathway is involved in ATP-induced CBF changes. The anterior inferior cerebellar artery (AICA) of anesthetized pigmented guinea pigs was exposed, and ATP was perfused into the AICA. For CBF measurement, the bulla was opened and the 0.7 mm laser probe of a Perimed PF2B flowmeter was positioned on the basal turn of the cochlea. AICA perfusion of an ATP solution caused dose-dependent transient CBF increases. The maximum CBF increase induced was 220% of the baseline. In some animals, CBF showed a dual effect; a transient decrease followed by a longer-lasting increase. The perfusions of sodium nitroprusside (SNP) also resulted in dose-dependent CBF changes. The intravenous application of N(omega)-nitro-L-arginine methyl ester (L-NAME) significantly attenuated ATP-induced CBF increases, and enhanced ATP-induced decreases, but did not affect SNP-induced CBF changes. The ATP-induced CBF responses indicate that ATP plays a role in CBF regulation. The biphasic characteristic of the ATP-induced CBF change suggests the involvement of both P2x- and P2y-subtype purinoceptors. That L-NAME caused attenuation of the ATP-induced CBF increase implies that the ATP-induced CBF increase is mediated by the release of endothelium-derived relaxing factor, nitric oxide, following activation of endothelial P2y-purinoceptors in the cochlear vascular bed and/or cochlear supplying vessels.

Aromatic-aromatic ring interaction revisited with model compounds of Wilcox

Aromatic-aromatic nonbonded interactions have been reexamined using model compounds of Wilcox and collaborators (J. Am. Chem. Soc. 1994, 116, 4497). It was found that at low temperatures down to 210 degrees K, the population of the folded conformers (A) is higher than that of the unfolded conformers (B), suggesting that edge-to-face aromatic-aromatic ring interactions are in effect. However, the free energy difference between the two types of conformers did not vary linearly with temperature, which is against what we expected from the thermodynamic relationship of delta G = delta H-T delta S. This suggests that in the presence of solvent molecules a free energy cancellation effect operates between the two conformers. Although A has a free energy gain of only approximately 0.5 kcal/mol over B in organic solvents, as obtained by subtracting the solvent-induced unfolding effect, it could still be a significant energy with respect to conformational preference.

[Research on basilar membrane vibration of guinea pigs elicited by direct current pulse]

To investigate the electromotility of basilar membrane (BM) of guinea pigs in vivo, a couple of Platinum-iridium wire electrodes were placed into holes drilled in the scala vestibuli and scala tympani on the basal turn of cochlea separately. The organ of Corti was stimulated with rectangular direct current pulses. The displacement and velocity of BM were measured with Laser Doppler velocimeter. The results indicated that the displacement of BM elicited by current moved toward the scala where positive current was injected. The waveform of BM displacement was corresponding to the rectangular pulse of electric current step. Ringing responses could be seen at the onset and offset of current pulse that was the transient responses of outer hair cells. The frequency of the ringing was the same as that of characteristic frequency of partition in BM. It is supposed that the ringing of BM is an active process of depletive energy and participate with cochlear amplifier. In the insensitive cochlea or dead animal, direct current can still elicit a BM displacement but the ringing response is decreased or disappeared. This phenomenon is probably because of metabolic disturbance in damaged outer hair cells. The BM vibration induced by direct current is similar to that of induced by acoustic stimulation, which can transfer to other partition of BM by traveling wave. This characteristic has laid a foundation of electromotile hearing and electrically evoked otoacoustic emission.