Role of 20-HETE in mediating the effect of dietary K intake on the apical K channels in the mTAL

We have used the patch-clamp technique to study the effect of dietary K intake on the apical K channels in the medullary thick ascending limb (mTAL) of rat kidneys. The channel activity, defined by the number of channels in a patch and the open probability (NPo), of the 30- and 70-pS K channels, was 0.18 and 0.11, respectively, in the mTAL from rats on a K-deficient diet. In contrast, NPo of the 30- and 70-pS K channels increased to 0.60 and 0.80, respectively, in the tubules from animals on a high-K diet. The concentration of 20-hydroxyeicosatetraenoic acid (20-HETE) measured with gas chromatography-mass spectrometry was 0.8 pg/microg protein in the mTAL from rats on a high-K diet and increased significantly to 4.6 pg/microg protein in the tubules from rats on a K-deficient diet. Addition of N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS) or 17-octadecynoic acid (17-ODYA), agents that inhibit the formation of 20-HETE, had no significant effect on the activity of the 30-pS K channels. However, DDMS/17-ODYA significantly increased the activity of the apical 70-pS K channel from 0.11 to 0.91 in the mTAL from rats on a K-deficient diet. In contrast, inhibition of the cytochrome P-450 metabolism of arachidonic acid increased NPo from 0.64 to 0.81 in the tubules from animals on a high-K diet. Furthermore, the sensitivity of the 70-pS K channel to 20-HETE was the same between rats on a high-K diet and on a K-deficient diet. Finally, the pretreatment of the tubules with DDMS increased NPo of the 70-pS K channels in the mTAL from rats on a K-deficient diet to 0.76. We conclude that an increase in 20-HETE production is involved in reducing the activity of the apical 70-pS K channels in the mTAL from rats on a K-deficient diet.

[Central low frequency hearing loss]

OBJECTIVE

To study the pathogenesis of the bilateral central low frequency hearing loss.

METHODS

Audiologic findings [auditory brainstem response(ABR), evoked otoacoustic emission (EOAE), et al] of 101 cases with bilateral central low frequency hearing loss were studied.

RESULTS

The typical clinical manifestations of bilateral central low frequency hearing loss were normal EOAE which cannot be suppressed by contralateral white noise, abnormal ABR, no acoustic reflex and--SP/AP > 0.44.

CONCLUSIONS

The results suggest that cochlear outer hair cells are normal in function with dysfunction of the cochlear nuclei. The main lesion of the disease are neural pathways related to Acoustic reflex and medial olivo-cochlear efferent nervous system. The cochlear afferent nerve may also be involved.

[Self-assembly of nano-structured silver particle and its surface-enhanced Raman spectroscopic application]

Planar arrays of nano-structured silver particle were self-assembled on poly-lysine modified glass surfaces. SEM characterization indicates that silver particles were assembled as a sub-monolayer. A comparison of the UV/Vis spectra of silver colloid and the arrays demonstrates that the poly-lysine layer showed size selectivity for the self-assembling silver particles. Surface-enhanced FT-Raman spectrum of methylviolegen on the array reveals that Raman scattering in near IR region was mainly enhanced via a chemical enhancement mechanism.

[Cochlear hypoxia and mtDNA deletion: possible correlated factors to cause presbycusis]

OBJECTIVE

To find the relationship among the most common mitochondrial DNA (mtDNA) 4,977 bp deletion, aging and deterioration of acoustic organ and determine the pathologic factors causing mtDNA 4,977 bp deletion.

METHODS

Sixty-seven temporal bones from a presbycusis group, an age-matched control group and a young control group were evaluated. The nested PCR and tri-nested PCR techniques were used to test the presence of mtDNA 4,977 deletion. Computer imaging processing was used to measure the parameters of blood vessels in the internal acoustic meatus.

RESULTS

Temporal bones from patients aged 50 years or over frequently showed mtDNA 4,977 deletions. In presbycusis patients, 17 of 34 ears showed mtDNA 4,977 deletion, whereas only 4 of 19 ears from the age-matched control group showed mtDNA 4,977 deletions. mtDNA 4,977 deletions were often seen in the spiral ganglion and vestibular ganglion neurons. In the presbycusis group, the lumen of the vasa nervosum of the internal auditory meatus showed a more severe reduction in patients with mtDNA 4,977 deletion than in those without deletion.

CONCLUSION

There is a strong correlation between presbycusis and mtDNA 4,977 deletion. We hypothesize that cochlear hypoxia may cause mtDNA 4,977 deletions and other mtDNA mutants which in turn may cause a reduction of mitochondrial oxidative phosphorylation and decreased auditory nerve function. The symptoms of neural presbycusis, however, may appear only after mtDNA metabolism decreases below a specific threshold.

[Two-dimensional surface Raman imaging of a roughened iron electrode in saline solution]

By using a confocal microprobe Raman system and proper surface roughening procedure for iron, the pit corrosion behavior of bare iron electrode in 3.4% NaCl (saline solution) solution has been investigated. The surface-enhanced Raman scattering (SERS) spectra of the corrosion products due to the pit corrosion at positive potential was obtained with high ratio of signal to noise. The application of SERS technique has been extended successfully to the study of iron corrosion. The two-dimensional surface Raman imaging acquired at 660 cm-1 was obtained also with the utility of surface Raman image technique. Results show that different iron oxides should coexist in the pit corrosion region and the distribution of the corrosion products was not uniform.

[Resonance Raman and surface-enhanced Raman spectroscopic study of microperoxidase-11]

The electron transfer and structure of microperoxidase-11 (MP-11) in solution and at electrode/solution interface were studied by electrochemical, resonance Raman and surface-enhanced Raman spectroscopic techniques. Results show that the central iron in heme group was six-coordinated in solution, whereas it was converted to five-coordinated state as MP-11 was adsorbed on the surface of a roughened silver electrode, due to the reorientation of MP-11 molecules. The electrochemical properties of MP-11 were directly affected by the coordination state of heme iron.

Protein-tyrosine phosphatase reduces the number of apical small conductance K+ channels in the rat cortical collecting duct

Previous studies have demonstrated that an increase in the activity of protein-tyrosine kinase (PTK) is involved in the down-regulation of the activity of apical small conductance K(+) (SK) channels in the cortical collecting duct (CCD) from rats on a K(+)-deficient diet (). We used the patch clamp technique to investigate the role of protein-tyrosine phosphatase (PTP) in the regulation of the activity of SK channels in the CCD from rats on a high K(+) diet. Western blot analysis indicated that PTP-1D is expressed in the renal cortex. Application of 1 microm phenylarsine oxide (PAO) or 1 mm benzylphosphonic acid, agents that inhibit PTP, reversibly reduced channel activity by 95%. Pretreatment of CCDs with PAO for 30 min decreased the mean NP(o) reversibly from control value 3.20 to 0.40. Addition of 1 microm herbimycin A, an inhibitor of PTK, had no significant effect on channel activity in the CCDs from rats on a high K(+) diet. However, herbimycin A abolished the inhibitory effect of PAO, indicating that the effect of PAO is the result of interaction between PTK and PTP. Addition of brefeldin A, an agent that blocks protein trafficking from Golgi complex to the membrane, had no effect on channel activity. Moreover, application of colchicine, a microtubule inhibitor, or paclitaxel, a microtubule stabilizer, had no effect on channel activity. In contrast, PAO still reduced channel activity in the presence of brefeldin A, colchicine, or paclitaxel. Furthermore, the effect of PAO on channel activity was absent when the tubules were bathed in 16% sucrose-containing bath solution or treated with concanavalin A. We conclude that PTP is involved in the regulation of the activity of SK channels and that inhibition of PTP may facilitate the internalization of the SK channels.

[Dynamic analysis of junctional sequences of T cell receptor (TCR) delta and gamma gene rearrangement in childhood with acute lymphoblastic leukemia]

OBJECTIVE

To explore the junctional sequence difference of T cell receptor delta and gamma gene rearrangement in childhood acute lymphoblastic leukemia (ALL) at diagnosis, complete remission (CR) and relapse.

METHODS

By using the T-vector molecular cloning and sequencing and polymerase chain reaction, the junctional sequences of TCRdeltaV-D and TCRgammaV-J were dynamically analyzed in 34 bone marrow samples of ALL.

RESULTS

The junctional sequence of TCR delta, gamma gene showed significant difference and regularity before and after remission and during relapsed periods. The sequence of TCRdeltaV-D were analyzed in 24 samples from ALL. Among them, the intact Vdelta2 and 5'Ddelta3 sequences were observed in 10 samples at diagnosis, of which 7 samples had T-->C mutation in Ddelta3 nonamer sequence. The deletions of rearranged Vdelta2, 5'Ddelta3 and Ddelta3 haptamer sequences were found in 11 complete remission (CR) samples with ALL, but none had T-->C mutation in Ddelta3 nonamer sequence. The deletion rate of Vdelta2 or Ddelta3 sequences and the T-->C mutation in Ddelta3 nonamer sequence were extremely differed between samples at diagnosis and in remission (calculate exact probabilities P = 0.001). The junctional rearrangement sequence of 5'Ddelta3 sequences tended to remain intact in 3 relapsed samples. The findings of TCRgammaV-J sequences were similar to that of TCRdeltaV-D in 10 ALL patients.

CONCLUSION

The difference of TCRdeltaV-D and TCRgammaV-J junctional sequences were related to the development, therapeutic effectiveness and outcome in ALL.

Development of Weather-Dependent Flow Requirements for River Temperature Control

/ Streamflow influences biological processes, habitat, and ecological integrity of streams in a number of vital ways. The establishment of weather-dependent minimum flows is essential to the protection of the aquatic environment and wildlife habitat from the adverse impacts of high water temperatures and to the effective utilization of the assimilative capacity of instream flows. In this study, weather-dependent flow requirements for summer river temperature control are derived from quantitative temperature-flow relationships. Correlation and regression of historical data and an analytical solution to the basic heat balance equation are employed to quantify the impacts of stream flow on river temperatures. Five-year continuous field measurements from the Platte River, Nebraska, USA, are used to illustrate the practical application in water-quality management. The methods and results demonstrate the feasibility of temperature control through streamflow management to meet water temperature standards and protect the aquatic biota by setting the appropriate weather-related minimum river discharges. The flow requirements are evaluated by a comparison with a critical discharge. Information provided in this paper will assist in planning streamflow regulation, design of river and reservoir operations, and application of water-quality criteria in environmental management.KEY WORDS: River discharges; Flow management; Habitat; Water quality; Weather; Wildlifehttp://link.springer-ny.com/link/service/journals/00267/bibs/24n4p529.html</HEA

[Progress of surface enhanced Raman spectroscopic studies in nonaqueous systems]

In this report, we describe the applications and theoretical aspects of SERS phenomenon in nonaqueous systems, which mainly involves the structure of solid/nonaqueous system, the adsorption of some neutral and organic molecules, inorganic ions and other complex compound molecules, the process and mechanism of some electrochemical oxidation reduction reactions in organic solvents etc.. In this review, we also depict the similarities and differences in SER spectra of aqueous and non-aqueous systems.

[Omega-mercaptohexanoic acid self-assemble-modified gold electrode and its catalytic property for redox reaction of chlorophylls]

Omega-mercaptohexanoic acid (6-MHA) self-assemble-modified gold electrode has been made by the authors. The SERS spectrum and the variations of double-layer capacitance (Cd) which occurred in the formation of 6-MHA self-assembled monolayers (SAM) on gold electrode surface were studied. The structure model of this SAM was deduced. The results show that 6-MHA can form stable SAM on gold electrode, and this 6-MHA SAM electrode has obvious catalysis for the redox reaction of chlorophylls.

Effects of impulse noise on cortical response threshold and inner ear activity of succinic dehydrogenase and acetylcholinesterase in guinea pigs

The effects of impulse noise (firecrackers at 170 dB SPL, 1, 10, 20 rounds) on auditory cortical response threshold (CRT) and activity of succinic dehydrogenase (SDH) and acetylcholinesterase (AchE) in the inner ear were studied in 37 guinea pigs. The results showed that extent of damage in the cochlea was related to amount of exposure to the noise. Exposure to 10 rounds resulted in temporal threshold shift (TTS); to 20 rounds the result was permanent threshold shift (PTS). For the period when TTS existed, inverse correlation was noticed between enzyme activity change and CRT shift. The correlation could not be established when PTS was induced. The results suggest that the pathomechanism of PTS was more complex than that of TTS. The significance of the results is discussed.

[Nasal septal deviation in fetuses]

To investigate the etiology of nasal septal deviation, twenty-four fetal sinonasal specimens aged between 8-40 weeks of gestation were studied under light microscopy. Sixteen fetal heads aged between 32-40 weeks were examined using 2.7 mm 5 degrees Wolf endoscope. Five of 24 fetal sinonasal specimens were confirmed histopathologically to have deviated nasal septum. 1 of 16 fetal heads was considered to have nasal septal deviation. The existence of nasal septal deviation in fetuses was confirmed. To explain the embryogenesis, we suggested that maldevelopment of vomeropalatal complex is responsible for the formation of nasal septal deviation in fetuses.

[An ELISA assay for humulus scandens specific IgE antibodies]

OBJECTIVE

Humulus scandens pollen (HSP) has been proved to be the one of the most important causative factors of autumnal hay fever in China. We established an enzyme immunoassay for specific IgE against HSP by using monoclonal anti-IgE antibody to detect sIgE in 143 patients with autumnal hay fever and 30 healthy volunteers.

METHODS

An indirect method of ELISA was developed. The optimal conditions for the test were: coating the allergen at 4 degrees C overnight with a concentration of 12 micrograms/ml; the test serum was diluted 1:16 and incubated with allergen overnight at 37 degrees C; the most suitable dilution and incubative time of the peroxidase-conjugated mouse anti-human IgE antibody were 1:3,000 and 2 hours respectively.

RESULTS

The patients' serum level of sIgE was significantly higher than controls (P < 0.001) and correlated significantly with the degree of skin test reaction (P < 0.01). The concordance between the results of skin test and ELISA was 74%-83%. The specificity of the assay was confirmed by heat inactivation and multiple absorption experiments. The coefficients of variation for the intraassay and interassay reproducibility ranged from 1.20%-8.30% and 8.63%-9.22% respectively.

CONCLUSIONS

Determination of specific HSP IgE with ELISA assay shows good specificity, sensitivity and reproducibility. It favours clinical practice due to its lower cost.

[Dysfunction of medial olivocochlear system and its audiological test]

The function of medial olivocochlear system (MOC) in patients with three kinds of auditory diseases was tested in order to investigate the relationship between MOC and retrocochlear impairment. Suppressive effect of evoked otoacoustic emissions (OAEs) by contralateral white noise was used as the indicator to evaluate the function of MOC in patients with: (1) sensorineural deafness with definite otoacoustic emissions, (2) hyperacusis and (3) tinnitus. Dysfunction of MOC was found in nine cases out of sixteen patients with sensorineural deafness and six cases out of fifteen patients with tinnitus. Two cases of hyperacusis also showed MOC dysfunction. It was concluded that MOC dysfunction may exist in some patients with sensorineural hearing loss and tinnitus, and in patients with hyperacusis as well. It seemed likely that dysfunction of MOC may played a role in causing tinnitus and hyperacusis in these patients. Testing the function of MOC may provide a helpful way for differential diagnosis of cochlear and retrocochlear impairment in auditory system.

[SERS and electrochemistry studies on the inhibition of thiourea and phenyl-thiourea on iron]

An iron electrode was obtained by depositing a thin layer of iron on active silver electrode with overpotential deposition method. The E - I curve and SERS spectra of thiourea (TU) and phenyl-thiourea (PTU) adsorbed on the iron electrode surface were studied by means of electrochemistry and SERS spectroscopy. The results showed that both TU and PTU can be adsorbed on the iron electrode surface and the inhibition of PTU is better than TU in 0.1mol/L KCl solution. The adsorption mode of TU and PTU is similar in the interaction of S atom and iron surface. The cause of better inhibition effect of PTU lies in that the PTU can be more easily adsorbed on iron electrode because of more negative charge in its S atom and benzene ring in PTU is arranged away from the iron surface to form a rather compact adsorption layer due to steric hindrance.

Effects of high intensity impulse noise on ionic concentrations in cochlear endolymph of the guinea pig

OBJECTIVE

To investigate the effect of acoustic overstimulation on concentrations of cations in cochlear endolymph and analyze the relationship between the ionic changes in endolymph and the hearing loss.

METHODS

The endocochlear potentials (EP), K+, Na+ and Ca2+ concentration in cochlear endolymph were examined in vivo for normal and 167 +/- 2 dB SPL impulse noise exposed groups of guinea pig bored on time course by means of double-barreled ion-selective microelectrodes. Brain stem auditory evoked potential (BAEP) was used to evaluate the auditory function. Ca(2+)-ATPase activity was demonstrated cytochemically in the lateral cochlear wall as induced by Ando et al with slight modification.

RESULTS

The K+ and Ca2+ concentration exhibited significant changes in 8-hour groups (P < 0.05 for K+ and P < 0.01 for Ca2+). Then the K+ concentration was eventually resumed to the initial levels in accordance with the EP recovery in 7 days, while during the same period Ca2+ concentration was always significantly higher than that in control group (P < 0.01). The BAEP threshold shifts were correlated well with changes in ionic concentrations, especially Ca2+ (P < 0.001), in the endolymph induced by acoustic trauma. Although the normal positive EP was observed 7 days after noise exposure, the function of the vascular stria was not completely restored as revealed by the fact that the Ca(2+)-ATPase was diffused to the apical membrane surface.

CONCLUSIONS

Endolymph compartment intrinsic mechanism for maintaining ionic composition is seriously deteriorated after high impulse noise stimulation. The changes of the unique environment of endolymph may play an important role in the mechanism of sensorineural hearing loss induced by acoustic trauma.

Analysis of small hair bundles in the utricles of mature guinea pigs

HYPOTHESIS

This study aimed to determine whether hair cells with immature hair bundles exist in the normal utricular maculae of mature guinea pigs.

BACKGROUND

A low rate of hair cell "turnover" occurs in the vestibular organs of normal adult birds. Small immature-appearing hair cells have been identified in the utricles of juvenile guinea pigs, but their existence in the vestibular system of mature mammals has not been confirmed.

METHODS

Nine utricles from 14- to 16-week-old guinea pigs were processed for scanning electron microscopy. A systematic search for small hair bundles was made. These bundles were classified as either "newborn-like" or "intermediate" depending on specific characteristics of the apical cell surface, the stereocilia, and the kinocilium.

RESULTS

A mean of 7 newborn-like and 41 intermediate hair bundles per utricle were identified. The average hair cell count for the guinea pig utricular macula was 7,200; thus, these small hair bundles comprise 0.7% of the total.

CONCLUSIONS

The small hair bundles are interpreted as developing vestibular hair cells, produced to replace hair cells lost to normal processes. This is thought to represent a biologic phenomenon that is in some ways similar, but in other ways distinct, from hair cell regeneration after trauma.

[SERS and electrochemistry studies on the structure of thiourea adsorption layer on silver electrode]

The structure of thiourea adsorption layer on silver electrode was studied by SERS and electrochemistry. It was found that the thiourea can be adsorbed on the electrode surface and can inhibit the reaction of hydrogen separation. And a change in structure of the thiourea adsorption layer on electrode surface took place at the voltage of about -0.6V. The further SERS experiment showed that the thiourea adsorption layer has a loose structure at about -0.9V and a compact structure at about -0.3V - -0.5V. The transition region is at about -0.6V - -0.8V.

[Topographic mapping of slow cortical response in guinea pigs]

Auditory slow cortical responses (SCR) were studied in 10 awake guinea pigs using topographic mapping techniques. Fourteen electrodes were installed through the guinea pig skull and fixed with dental cement. Auditory SCRs were recorded via 13 leads and brain maps were realized on a concerto system. The results showed that SCRs were relatively stable at the temporal lobe, with a stable positivity (31.25-37.50 ms TP) followed by a negativity (62.50-72.50 ms TN). Variability was seen at other leads. The foci of maximum positivity and negativity were seen at the temporal cortex. The results suggest that there are multiple contributions to SCRs which partially overlap in time, and that auditory cortex contribute significantly more than other sources. SCRs also received auditory information in parallel from the brainstem. The focus of AM-evoked SCRs was seen located at temporal lobe while that of FM-evoked SCRs at temporal and frontal lobes. It suggests that intensity analysis is essentially completed at the temporal cortex whereas precise frequency discrimination relies on function of higher integrating centers.

[Effects of short-term tone exposure on DPOAEs]

Test parameter combinations are known to affect DPOAE measurement. The present study was attempted to find out if different test parameter combinations affect DPOAEs' utility in reflecting the change of cochlear function. Pure tones of moderate intensity (82 dB SPL) and short duration (3 min) were introduced into rabbit's ear canal to cause temporary change of cochlear mechanics, and the change of amplitude of 2f1-f2 DPOAE representing 10 kHz over 10 minutes after the exposure was monitored using equal- and different primary level combinations. It was found that, under the same exposure condition, 2f1-f2 DPOAEs induced by primaries of different levels (L2 = L1 - 12 dB) had showed more initial reduction in amplitude and slower recovery than that induced by primaries of equal levels (L1 = L2). The difference may indicate that there are multiple physiological processes that contribute to the generation of 2f1-f2 DPOAE and that change of DPOAE test parameters may selectively reveal different DPOAE generating processes.

An observation on otoacoustic emission and ultrastructure of cochlea in experimental autoimmune inner ear disease

OBJECTIVE

To acquire the detailed knowledge of immune lesion of inner ear.

METHODS

A simultaneous study on physiology and ultrastructure was carried out in guinea pigs immunized with homogenous inner ear antigen. The specific antibody was analysed by a modified immunotransfer electrophoresis method.

RESULTS

Three positive bands (with molecular weights of 68.0 kD, 62.7 kD and 60.1 kD) were found in all the sera of immunized animals but not in the control animals. Threshold shift of auditory brainstem response over 10dB HL was found in 42% of secondary system immunized animals and 32% of secondary endolymphatic sac (e.sac) immunized animals. Amplitude of distortion production otoacoustic emission dropped obviously in the above two groups. Transmission electron microscope showed the mitochondria of outer hair cells in the cochlea was impaired in animals with auditory disorder.

CONCLUSIONS

The research suggests that the immune reaction against homogenous inner ear antigen results in dysfunction of hydroxycorticosteroid during the early stage.