Crystal Structure Analysis of the Repair of Iron Centers Protein YtfE and Its Interaction with NO.

Molecular mechanisms underlying the repair of nitrosylated [Fe-S] clusters by the microbial protein YtfE remain poorly understood. The X-ray crystal structure of YtfE, in combination with EPR, magnetic circular dichroism (MCD), UV, and (17) O-labeling electron spin echo envelope modulation measurements, show that each iron of the oxo-bridged Fe(II) -Fe(III) diiron core is coordinatively unsaturated with each iron bound to two bridging carboxylates and two terminal histidines in addition to an oxo-bridge. Structural analysis reveals that there are two solvent-accessible tunnels, both of which converge to the diiron center and are critical for capturing substrates. The reactivity of the reduced-form Fe(II) -Fe(II) YtfE toward nitric oxide demonstrates that the prerequisite for N2 O production requires the two iron sites to be nitrosylated simultaneously. Specifically, the nitrosylation of the two iron sites prior to their reductive coupling to produce N2 O is cooperative. This result suggests that, in addition to any repair of iron centers (RIC) activity, YtfE acts as an NO-trapping scavenger to promote the NO to N2 O transformation under low NO flux, which precedes nitrosative stress.

Rheological and functional properties of composite sweet potato - wheat dough as affected by transglutaminase and ascorbic acid.

Effect of transglutaminase (TGM) and ascorbic acid (AA) on composite sweet potato - wheat dough functional and rheological properties was studied. Partial substitution of wheat flour with sweet potato flour at the level of 20 % significantly (P ≤ 0.05) reduced glutenin, gliadin, dough stability, protein weakening, storage modulus (G') and viscous modulus (G″). Mixolab revealed that both TGM and AA treated dough had stability and protein weakening closed to wheat dough (control), with TGM treated dough having the highest values. TGM Introduced new cross-link bonds as shown by the change of amino acid concentration, leading to an increase in storage modulus (G') and viscous modulus (G″), with G' being higher at all levels of TGM concentration. The opposite was observed for composite dough treated with AA as measured by controlled - stress rheometer. TGM treatment increased glutenin and gliadin content. Compared with the control, dough treated with AA exhibited high molecular weight of polymers than TGM treated dough. The results indicate that the TGM and AA modification of the mixolab and dynamic rheological characteristics (G' and G″) dependent on the changes of GMP, glutenin, gliadin and protein weakening in the composite dough. TGM and AA treatment could improve functional and rheological properties of sweet potato - wheat dough to levels that might be achieved with normal wheat bread. However, it's extremely important to optimize the concentrations of both additives to obtain the optimum response.

Investigation of the Source of Snoring Sound by Drug-Induced Sleep Nasendoscopy.

OBJECTIVE: To investigate the source of snoring sound in patients with simple snoring (SS) and different degrees of obstructive sleep apnea syndrome (OSAS) in order to provide a basis for the surgical treatment of snoring. METHODS: Fifty-two patients with either SS or OSAS (with an apnea-hypopnea index ≤40) underwent drug-induced sleep nasendoscopy (DISN). Vibration sites in the pharyngeal cavity were observed. RESULTS: Vibration of the soft palate, pharyngeal lateral wall, epiglottis, and tongue base appeared in 100, 53.8, 42.3, and 26.9% of the patients, respectively. The source of snoring sound was divided into two types: palatal fluttering only (type I) and multisite vibration (type II). The latter was divided into 3 subtypes: palatal fluttering with epiglottis vibration (type IIa), palatal fluttering with lateral wall vibration (type IIb), and palatal fluttering with vibration of the lateral wall, epiglottis, and tongue base together (type IIc). The distribution of type I snoring was the highest in SS patients. Type IIb was more common in patients with medium and severe OSAS. Type IIc was most common in patients with severe OSAS. CONCLUSION: The source of snoring sound is diverse, with SS and OSAS patients showing different features. DISN is a very effective method of identifying the snoring source.

[Effects of nasal cavity enlarging surgery on snoring in obstructive sleep apnea hypopnea syndrome patients].

OBJECTIVE: To explore the efficacies of nasal cavity enlarging surgery in obstructive sleep apnea hypopnea syndrome (OSAHS) patients with nasal obstruction. METHODS: From April 2011 to October 2012, a total of 22 OSAHS patient with nasal obstruction underwent nasal cavity enlargement. Natural overnight snoring was digitally recorded, polysomnography (PSG) performed simultaneously and nasal resistance measured at pre- and post-operation. Body mass index (BMI), Epworth sleepiness scale (ESS), apnea-hypopnea index (AHI), minimum oxygen saturation SaO2, total nasal resistance, peak frequency, maximal frequency, mean frequency, central frequency and power ratio 800 Hz of snores were recorded and compared. RESULTS: BMI and SaO2 rose while AHI and ESS declined post-operatively. No statistical difference existed between pre-operation and post-operation. The total nasal resistance was (0.39 ± 0.15) and (0.29 ± 0.11) Pa·cm(-3)·s(-1) at pre- and post-operation. And there was significant statistical difference (P < 0.01) . The snores at pre- and post-operation exhibited different patterns in time and power spectrum distribution domains. And fmax, fpeak and fmean declined while fc and PR800 rose at post-operation. Significant statistical differences existed in the change of fpeak and PR800 at pre- and post-operation (P < 0.01) . CONCLUSION: Nasal cavity enlargement can lessen nasal resistance and change the acoustic characteristics of snoring in OSAHS patients. The postoperative snoring focus of lower frequency suggests that acoustic parameters of snores may be used to evaluate the efficacy of OSAHS surgery.

Identification of critical amino acids in an immunodominant IgE epitope of Pen c 13, a major allergen from Penicillium citrinum.

BACKGROUND: Pen c 13, identified as a 33-kDa alkaline serine protease, is a major allergen secreted by Penicillium citrinum. Detailed knowledge about the epitopes responsible for IgE binding would help inform the diagnosis/prognosis of fungal allergy and facilitate the rational design of hypoallergenic candidate vaccines. The goal of the present study was to characterize the IgE epitopes of Pen c 13. METHODOLOGY/PRINCIPAL FINDINGS: Serum samples were collected from 10 patients with mold allergy and positive Pen c 13 skin test results. IgE-binding epitopes on rPen c 13 were mapped using an enzymatic digestion and chemical cleavage method, followed by dot-blotting and mass spectrometry. A B-cell epitope-predicting server and molecular modeling were used to predict the residues most likely involved in IgE binding. Theoretically predicted IgE-binding regions were further confirmed by site-directed mutagenesis assays. At least twelve different IgE-binding epitopes located throughout Pen c 13 were identified. Of these, peptides S16 (A(148)-E(166)) and S22 (A(243)-K(274)) were recognized by sera from 90% and 100% of the patients tested, and were further confirmed by inhibition assays. Peptide S22 was selected for further analysis of IgE-binding ability. The results of serum screening showed that the majority of IgE-binding ability resided in the C-terminus. One Pen c 13 mutant, G270A (T(261)-K(274)), exhibited clearly enhanced IgE reactivity, whereas another, K274A, exhibited dramatically reduced IgE reactivity. CONCLUSIONS/SIGNIFICANCE: Experimental analyses confirmed in silico-predicted residues involved in an important antigenic region of Pen c 13. The G270A mutant of Pen c 13 has the potential to serve as an additional tool for the diagnosis/prognosis of mold allergy, and the K274A mutant, as a hypoallergenic form of the epitope, may provide a framework for the design and development of a safe and efficient therapeutic strategy for treating human allergic diseases.

The role of sulfatide lipid domains in the membrane pore-forming activity of cobra cardiotoxin.

Cobra CTX A3, the major cardiotoxin (CTX) from Naja atra, is a cytotoxic, basic ß-sheet polypeptide that is known to induce a transient membrane leakage of cardiomyocytes through a sulfatide-dependent CTX membrane pore formation and internalization mechanism. The molecular specificity of CTX A3-sulfatide interaction at atomic levels has also been shown by both nuclear magnetic resonance (NMR) and X-ray diffraction techniques to reveal a role of CTX-induced sulfatide conformational changes for CTX A3 binding and dimer formation. In this study, we investigate the role of sulfatide lipid domains in CTX pore formation by various biophysical methods, including fluorescence imaging and atomic force microscopy, and suggest an important role of liquid-disordered (ld) and solid-ordered (so) phase boundary in lipid domains to facilitate the process. Fluorescence spectroscopic studies on the kinetics of membrane leakage and CTX oligomerization further reveal that, although most CTXs can oligomerize on membranes, only a small fraction of CTXs oligomerizations form leakage pores. We therefore suggest that CTX binding at the boundary between the so and so/ld phase coexistence sulfatide lipid domains could form effective pores to significantly enhance the CTX-induced membrane leakage of sulfatide-containing phosphatidylcholine vesicles. The model is consistent with our earlier observations that CTX may penetrate and lyse the bilayers into small aggregates at a lipid/protein molar ratio of about 20 in the ripple P(ß)' phase of phosphatidylcholine bilayers and suggest a novel mechanism for the synergistic action of cobra secretary phospholipase A2 and CTXs.

[Preliminary exploration of Gd-DTPA enhanced inner ear image of guinea pig using magnetic resonance scan].

OBJECTIVE: To observe the distribution of Gd-DTPA in the inner ear of guinea pig by MRI at different time points after intratympanic administration, explore the optical time for observing the whole inner ear. To study the pharmacokinetic feature of Gd-DTPA in the inner ear, and find out whether discrimination of endolymph and perilymph can be obtained under current conditions. METHODS: Sixty-five guinea pigs were randomly divided into 13 groups, after diluted Gd-DTPA intratympanic injection, each group of guinea pigs were scanned through MRI (3D-T1 FSE sequence) at different time points (0 h, 0.5 h, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h, 12 h, 24 h, 48 h, 72 h, 96 h). Pixel intensity values of some locations in the inner ear were analyzed using e-Film software, then pixel intensity was converted into concentration using the results of previous in-vitro study. ABR thresholds of bilateral ears before, 1 d and 7 d after intratympanic injection were compared. RESULTS: Six hours after transtympanic Gd-DTPA injection was the time point when contrast agent was distributed all over the inner ear, and reached a high concentration: 589.29, 552.54, 570.17, 255.08, 107.09 and 139.18 µmol/L in the vestibule, scala vestibuli and scala tympani of basal turn, the 2(nd), the 3(rd) and the apical turn individually, that was also the optimal time for observing the whole inner ear by MRI. Perilymph appeared to be preferentially enhanced relative to the endolymph, resulting in a distinction between the scales of the inner ear. There was no significant difference between the experimental ear (diluted GD-DTPA injected ear) and contrast ear (physiological saline injected ear) on 1 d and 7 d. CONCLUSIONS: The best time getting MRI imaging after intratympanic diluted GD-DTPA injection is 6 h. After diluted agent injection perilymph can be enhanced so as to be differentiated with endolymph by MRI, diluted agent have no obvious effect on the ABR threshold. The pharmacokinetic feature of Gd-DTPA in the inner can be studied using MRI.

Peptide-bound dinitrosyliron complexes (DNICs) and neutral/reduced-form Roussin's red esters (RREs/rRREs): understanding nitrosylation of [Fe-S] clusters leading to the formation of DNICs and RREs using a de novo design strategy.

This manuscript describes the interaction of low-molecular-weight DNICs with short peptides designed to explore the stability and structure of DNIC-peptide/RRE-peptide constructs. Although characterization of protein-bound and low-molecular-weight DNICs is possible via EPR, XAS, and NRVS, this study demonstrates that the combination of aqueous IR ν(NO) and UV-vis spectra can serve as an efficient tool to characterize and discriminate peptide-bound DNICs and RREs. The de novo chelate-cysteine-containing peptides KC(A)(n)CK-bound (n = 1-4) dinitrosyliron complexes KC(A)(n)CK-DNIC (CnA-DNIC) and monodentate-cysteine-containing peptides KCAAK-/KCAAHK-bound Roussin's red esters (RREs) KCAAK-RRE/KCAAHK-RRE were synthesized and characterized by aqueous IR, UV-vis, EPR, CD, XAS, and ESI-MS. In contrast to the inertness of chelate-cysteine-containing peptide-bound DNICs toward KCAAK/KCAAHK, transformation of KCAAK-RRE/KCAAHK-RRE into CnA-DNIC triggered by CnA and reversible transformation between CnA-DNIC and CnA-RRE via {Fe(NO)(2)}(9)-{Fe(NO)(2)}(10) reduced-form peptide-bound RREs demonstrate that the {Fe(NO)(2)}(9) motif displays a preference for chelate-cysteine-containing peptides over monodentate-cysteine-containing peptides. Also, this study may signify that nitrosylation of [Fe-S] proteins generating protein-bound RREs, reduced protein-bound RREs, or protein-bound DNICs are modulated by both the oxidation state of iron and the chelating effect of the bound proteins of [Fe-S] clusters.

Surface pressure-dependent interactions of secretory phospholipase A2 with zwitterionic phospholipid membranes.

The hydrolytic activity of secretory phospholipase A(2) (PLA(2)) is regulated by many factors, including the physical state of substrate aggregates and the chemical nature of phospholipid molecules. In order to achieve strong binding of PLA(2) on its substrates, many previous works have used anionic lipid dispersion to characterize the orientation and penetration depth of PLA(2) molecules on membrane surfaces. In this study, we applied monolayer technique with controllable surface area to investigate the PLA(2)s of Taiwan cobra venom and bee venom on zwitterionic phophatidylcholine monolayers and demonstrated an optimum hydrolytic activity at a surface pressure of 18 and 24 mN/m, respectively. By combining polarized attenuated total reflection Fourier-transform infrared spectroscopy and monolayer-binding experiments, we found that the amount of membrane-bound PLA(2) decreased markedly as the surface pressure of the monolayer was increased. Interestingly, the insertion area of the PLA(2)s decreased to near zero as the surface pressure increased to the optimum pressure for hydrolytic activity. On the basis of the measured infrared dichroic ratio, the orientation of the PLA(2)s bound to zwitterionic membranes was similar to that observed on a negatively charged membrane and was independent of the surface pressure. Our findings suggest that both PLA(2)s were located on the membrane surface rather than penetrating the membrane bilayer and that the deeply inserted mode is not a favorable condition for the hydrolysis of phospholipids in zwitterionic phospholipid membranes. The results are discussed in terms of the easy access of catalytic water for the PLA(2) activity and the mobilization of its substrate and product to facilitate the catalytic process.

[Non-invasive visualization of endolymphatic hydrops in patients with Meniere's disease].

OBJECTIVE: To visualize the endolymph in Meniere's disease by applying for non-invasive intratympanic gadolinium through eustachian tube and three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI). METHODS: With a 3 Tesla magnetic resonance imaging (MRI) unit, 3D-FLAIR imaging was performed 24 h after intratympanic gadolinium through eustachian tube in seven patients with Meniere's disease. Pure tone test was performed 24 h before and after administered gadolinium. Tympanometry was performed 24 h before, 24 h and 3 months after administered gadolinium. RESULTS: In five patients, the gadolinium could appear in parts of the perilymph inside the inner ear but not in the middle ear and mastoid, moreover, the border between the perilymph and endolymph was visible so that endolymphatic space was clearly shown on 3D-FLAIR imaging. In two patients with endolymphatic hydrops, the perilymphatic space surrounding endolymph was small or disappeared. In two patients, the gadolinium could appear in parts of the middle ear and mastoid but not in the inner ear. No significant changes in pure tone test and tympanometry were noted. CONCLUSIONS: 3D-FLAIR MRI with intratympanic gadolinium through eustachian tube could clearly reveal the visualization of endolymphatic space in Meniere's disease.

[Clinical features of multiple canal involvement in benign paroxysmal positional vertigo].

OBJECTIVE: To describe a series of patients with multiple canal involvement in benign paroxysmal positional vertigo (BPPV), with respect to diagnosis and management. METHODS: Ninety-five individuals with symptoms of BPPV and positional nystagmus were included in this study. The diagnosis was based on a history of brief episodes of vertigo and the presence of multiple positional nystagmus as confirmed by video-oculographic examination. Patients were treated by means of different particle repositioning manoeuvres according to the affected canal. RESULTS: Ninety-five patients showed multiple positional nystagmus during the examination corresponding to simultaneous multi-canal BPPV. Fourteen patients (14.7%) had bilateral canal BPPV. Six patients had bilateral posterior canal. Six patients had bilateral horizontal canal, and two patients had bilateral anterior canal. Fifty-three patients (55.8%) had torsional, up-beating nystagmus with down-beating nystagmus, which suggested possible affected both of posterior and anterior canals. Twenty patients (21.1%) had torsional up-beating nystagmus and horizontal direction nystagmus, which suggested possible affected both of posterior and horizontal canals. Five patients had down-beating nystagmus with horizontal nystagmus, which suggested affected both of anterior and horizontal canals. Three patients had torsional up-beating with down-beating and horizontal nystagmus, which suggested possible affected multiple canals. Treatment given to the patients varied according to the canal affected, started with the canal that elicited a strong positional nystagmus and vertigo, and 93.7% (89/95) of patients were symptom free or improved. CONCLUSIONS: It has been found that multi-canal BPPV is not a rate observation in clinic, and most of them affected posterior and anterior canals. Treatment of multi-canal BPPV can be effective using repositioning maneuver.

The water-soluble Roussin's red ester acting as a potential photochemical NO-delivery agent: photolysis reactions, DNA cleavage and anticancer activity.

The water-soluble Roussin's red ester [(NO)(2)Fe(mu-SCH(2)CH(2)P(O)(CH(2)OH)(2))(2)Fe(NO)(2)] (1), a potential photochemical prodrug of an NO precursor, was synthesized from the reaction of HSCH(2)CH(2)P(O)(CH(2)OH)(2) (F) and [Fe(CO)(2)(NO)(2)]. The IR v(NO) stretching frequencies of complex 1 appear at 1759 (s), 1784 (s) and 1816 (w) cm(-1) in buffer (pH = 7.4). NO was released with a stoichiometry ratio Delta[NO]/Delta[1] = 3.6 +/- 0.2 when complex 1 was exposed to UV in deaerated aqueous phosphate buffer solution. Here light acts as an On/Off switch for NO release. Incubation of pBR322 supercoiled DNA with complex 1, followed by irradiation, produced DNA strand breakage. In contrast to the addition of carboxy-PTIO (NO radical scavenger), DNA strand breakage was not inhibited when the scavengers of hydroxyl radical and singlet oxygen were added. Complex 1 irradiated under a N(2) atmosphere exhibited the same cleavage efficiency as complex 1 irradiated under air. The results show that DNA strand cleavage efficiency depends on the concentration of complex 1, the pH value of the buffer, and the duration of the photolysis of complex 1. The conversion rate from supercoiled (SC form) to nicked circular (NC form) of complex 1 was 2.96 x 10(-2) s(-1). The results of a T4 ligase enzymatic assay reveals the nonhydrolytic DNA breakage mechanism. The NO-release ability of complexes 1, 2, and 3 follows the order 1 > 2 > 3. Upon UV-irradiation, complex 1 exhibits cytotoxicity against B16-F10 mouse melanoma cells.

Fluorescence single-molecule study of cobra phospholipase A2 action on a supported gel-phase lipid bilayer.

Previous nanoscale investigations of the gel-state membrane surface structure under the action of phospholipase A(2) (PLA(2)) suggest that single enzymes at work scoot on the membrane surface from the observed defects, which creates nanosized channels oriented along the lipid crystal-packing structure. To date, however, there have been no reports of direct observation of PLA(2) at the single-molecule level focusing on how the enzymes interact with the defects. Herein, we report a single-molecule fluorescence microscopy study on the action of enzymatically active rhodamine B-labeled cobra PLA(2) on a supported lipid membrane with visible packing defects on a glass substrate. Working with a gel-state phospholipid bilayer, the low-activity period (lag phase) of PLA(2) action is followed by the burst binding of PLA(2) molecules from aqueous solution on a few newly created active sites. These active sites are distinguished by a spatial resolution of approximately 40 nm, which is below the diffraction limit. The rate of active-site propagation as reflected by new PLA(2) binding on the membrane surface is estimated to be approximately 5 nm min(-1). This rate is about two orders of magnitude slower than the propagation rate of hydrolyzed channels estimated by AFM studies on bee venom PLA(2) on a similar membrane surface. This direct observation of PLA(2) molecules allows the visualization of different PLA(2) binding modes on the membrane surface and on the membrane boundary.

[Vestibular pathology associated with noise-induced inner ear impairment].

OBJECTIVE: To evaluate the pathological status of the vestibular system associated with noise-induced inner ear impairment. METHODS: Totally 68 patients with noise-induced hearing loss (NIHL) who presented with vestibular symptoms including vertigo, dizziness, and chronic disequilibrium were screened. All patients underwent a series of conventional vestibular function tests and vestibular autorotation test and the results were retrospectively reviewed and evaluated. RESULTS: Sixty-eight (14.5%) patients with NIHL were identified among 469 patients with vertigo, dizziness, or imbalance. A pure tone hearing threshold of patients with vertigo and NIHL at 4000 Hz were between 30 dB HL and 80 dB HL with an average threshold of (46.7 +/- 17.6) dB HL in left ear and (37.3 +/- 16.7) dB HL in right ear. Patients with symmetrical hearing loss at 4000 Hz accounted for 41.7% and those with asymmetrical loss accounted for 58.3%. Vestibular pathologies included benign positional paroxysmal vertigo (45.7%), unilateral decreased caloric responses (20.0%), bilateral decreased caloric responses (26.7%), abnormal vestibulo-spinal reflex function (28.6%), vestibular function response hyperactivity (3.0%), and abnormal vestibulo-ocular reflex presentation at high frequencies (97.0%). CONCLUSIONS: Loud acoustic stimulation not only damages the cochlea but also causes clear functional impairment to the vestibular end organs. Although the vestibular pathology is not correlated with the severity of the hearing loss, it correlates with the subjective symptoms of the vestibular system.

[Endolymphatic visualization in patients with Meniere's disease].

OBJECTIVE: To attempt to visualize the endolymph in patients with Meniere's disease by applying non-invasive intratympanic gadolinium through eustachian tube and three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI). METHODS: With a 3 Tesla magnetic resonance imaging (MRI) unit, 3D-FLAIR imaging was performed 24 hours after intratympanic gadolinium through eustachian tube in two patients with medically active and intractable Meniere's disease. Pure tone test and tympanometry were performed 24 hours before and after the administration of gadolinium. RESULTS: The gadolinium appeared in almost all parts of the perilymph inside the inner ear; moreover, the border between the perilymph and the endolymph was visible so endolymphatic space was clearly shown on 3D-FLAIR. No change in pure tone test and tympanometry was noted. CONCLUSIONS: 3D-FLAIR MRI with intratympanic gadolinium through eustachian tube can clearly reveal the visualization of endolymph in patients with Meniere's disease. Intratympanic gadolinium therapy through eustachian tube is a safe and effective.

[Normal values of vestibular autorotation test in young people].

OBJECTIVE: To explore the normal values of vestibular autorotation test (VAT) in young people. METHODS: VAT was performed in 31 young people aged 20-30 years. The measured value were analyzed and compared with the reference normal value. RESULTS: The measured values of VAT in healthy young people are almost within the normal range of the general population. Compared with the reference normal values, the horizontal gains at 2.0, 2.3, 2.7, 5.5, and 5.9 Hz, the vertical gains at 2.0 and 5.9 Hz, and the vertical phases at 2.0, 2.3, 2.7, 3.1, 3.5, and 3.9 Hz were significantly different (P < 0. 05). No significant difference was shown in the horizontal phases and asymmetry. CONCLUSIONS: The normal values of VAT in young people is within the reference normal range of the general population. The vestibular function of young people may be more sensitive in lower frequency range (2-3Hz).

Role of glycosphingolipid conformational change in membrane pore forming activity of cobra cardiotoxin.

The major cardiotoxin from Taiwan cobra (CTX A3) is a pore forming beta-sheet polypeptide that requires sulfatide (sulfogalactosylceramide, SGC) on the plasma membrane of cardiomyocytes for CTX-induced membrane leakage and cell internalization. Herein, we demonstrate by fluorescence spectroscopic studies that sulfatides induce CTX A3 oligomerization in sulfatide containing phosphatidylcholine (PC) vesicles to form transient pores with pore size and lifetime in the range of about 30 A and 10(-2) s, respectively. These values are consistent with the CTX A3-induced conductance and mean lifetime determined previously by using patch-clamp electrophysiological experiments on the plasma membrane of H9C2 cells. We also derived the peripheral binding structural model of CTX A3-sulfatide complex in sulfatide containing PC micelles by NMR and molecular docking method and compared with other CTX A3-sulfatide complex structure determined previously by X-ray in membrane-like environment. The NMR results indicate that sulfatide head group conformation changes from a bent shovel (-sc/ap) to an extended (sc/ap) conformation upon initial binding of CTX A3. An additional global reorientation of sulfatide molecule is also needed for CTX A3 dimer formation as inferred by the difference between the X-ray and NMR complex structure. Since the overall folding of CTX A3 molecules remained the same, sulfatide in phospholipid bilayer is proposed to play an active role by involving its local and global conformational changes to promote both the oligomerization and reorientation of CTX A3 molecule for its transient pore formation and cell internalization.

[Diagnosis and therapy for benign paroxysmal positional vertigo of the anterior semicircular canal].

OBJECTIVE: To analyse the video-oculographic findings of positional tests and evaluate the efficacy of canalith repositioning procedure (CRP) in patients with paroxysmal positional vertigo ( BPPV) of the anterior semicircular canal (ASC). METHODS: A retrospective study of 31 patients with ASC BPPV. Then the CRP was performed. RESULTS: Twenty-two individuals (70.97%) presented a unilateral positional nystagmus during the Dix-Hallpike test, in 17 individuals had torsional nystagmus component, 5 individuals only had pure positional down beat nystagmus. Nine patients presented bilateral positional nystagmus, 7 individuals had torsional component positional nystagmus, in 2 patients the direction of the torsional component were the same during right and left Dix-Hallpike test, in 4 patients the torsional component were concurrent with positional down beat nystagmus but the direction could not be ascertained clinically, in 2 patients had pure positional down beat nystagmus. Nineteen patients (61.29%) had unilateral lesion, 11 patients had the left ASC BPPV, 8 patients had right ASC BPPV. Eleven patients had with both ASC and PSC BPPV in the ipsilateral. Twenty-one patients (67.74%) were cured, 29 patients (93.55%) were improved, 2 (6.45%) patients were inefficacy. CRP effectively resolved the nystagmus and vertigo in 14 patients (45.16%) when applied only once, The average number of CRP was 1.7 times, there were 5 patients recurrence during the follow-up. CONCLUSIONS: ASC BPPV was not a common condition. The torsional nystagmus component of ASC BPPV might be weak during the Dix-Hallpike test. The positional nystagmus of ASC BPPV was triggered bilaterally. Based on these findings, CRP could be one of the most effective treatment methods for ASC BPPV.

Structures of heparin-derived tetrasaccharide bound to cobra cardiotoxins: heparin binding at a single protein site with diverse side chain interactions.

Cobra cardiotoxins (CTXs) are three-fingered polypeptides with positively charged domains that have been shown to bind to anionic ligands of snake venom citrate, glycosaminoglycans, sulfoglycosphingolipid, and nucleotide triphosphate with various biochemical effects including toxin dimerization, cell surface retention, membrane pore formation, cell internalization and blocking of enzymatic activities of kinase and ATPase. The reported anionic binding sites, however, are found to be different among different CTX homologues for potentially different CTX activities. Herein, by NMR studies of the binding of inorganic phosphate, dATP (stable form of ATP), and heparin-derived tetrasaccharide to Naja atra CTX A1, a novel CTX molecule exhibiting in vivo necrotic activity on skeletal muscle, we demonstrate that diverse ligands binding to CTXs could also occur at a single protein site with flexible side chain interactions. The flexibility of such an interaction is also illustrated by the available heparin-CTX A3 complex structures with different heparin chain lengths binding at the same site. Our results provide a likely structural explanation on how the interaction between heparan sufate and proteins depends more on the overall charge cluster organization rather than on their fine structures. We also suggest that the ligand binding site of CTX homologues can be fine-tuned by nonconserved residues near the binding pocket because of their flexible side chain interaction and dimerization ability, even for the rigid CTX molecules tightened by four disulfide bonds.

[Clinical short-term effect of Meniett pulse generator for Meniere disease].

OBJECTIVE: To investigate the short-term efficacy and safety of transtympanic pressure treatment in the management of recalcitrant vertigo in Meniere disease in order to lead to the further long-term treatment. METHODS: Using cross-sectional case study, eighteen patients with medically intractable and active Meniere disease were opted to manage with Meniett pulse generator. A standard ventilation tube was inserted in the affected ear and the treatment period with Meniett pulse generator was 8 weeks. Patients indicated on the symptom report card and six-point functional scale the maximum level of vertigo, activity and stress. Hearing was assessed by pure tone average thresholds (PTA), moreover, electrocochleogram and vestibular caloric were performed. RESULTS: Of eighteen patients, the changes of vertigo severity, vertigo frequency, sick day and six-point functional scale between after and before treatment with Meniett were statistically significant (P < 0.05), moreover, the changes of--SP/AP between after and before treatment with Meniett were statistically significant (P < 0.05). No change in vestibular function was noted. Two of 18 patients showed a significant PTA increase of 10dB or more and hearing was stable in the remainder of patients 4 weeks after treatment with Meniett. Twelve of 18 patients showed a significant PTA increase of 10dB or more and hearing was stable in the remainder of patients 8 weeks after treatment with Meniett. There were no complications during 6-month follow-up with Meniett. CONCLUSIONS: Meniett seemed to be a safe, effective and non-destructive level of therapy, which could reduce vertiginous symptoms and functional handicap and showed an improvement of hearing in patients with medically intractable Meniere disease. This method was recommended before attempting any surgical or chemical vestibular ablation procedure.