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K Xu

Publications and source records attributed to K Xu.

At least 145 records · Page 8Linked to original sources
PubMed1998

Atomic force microscopy used for the surface characterization of microcapsule immunoisolation devices.

The surface morphology of the microcapsule used as a bioartificial pancreas was examined by atomic force microscopy (AFM) under ambient conditions in a liquid environment. The standard contact mode was used for imaging. The capsules exhibited different morphologies and surface roughness depending on the composition of the cation solution: namely, the mole ratio of antigelling and gelling cations [Na+]/[Ca2+]. Surface roughness parameters obtained by AFM measurements provide quantitative information on the surface properties of the capsular membrane. In this respect, AFM can be considered a valuable technique complementary to optical microscopy in providing feedback for capsule optimization.

Artificial Organs↗
PubMed1998

Calcium oscillations increase the efficiency and specificity of gene expression.

Cytosolic calcium ([Ca2+]i) oscillations are a nearly universal mode of signalling in excitable and non-excitable cells. Although Ca2+ is known to mediate a diverse array of cell functions, it is not known whether oscillations contribute to the efficiency or specificity of signalling or are merely an inevitable consequence of the feedback control of [Ca2+]i. We have developed a Ca2+ clamp technique to investigate the roles of oscillation amplitude and frequency in regulating gene expression driven by the proinflammatory transcription factors NF-AT, Oct/OAP and NF-kappaB. Here we report that oscillations reduce the effective Ca2+ threshold for activating transcription factors, thereby increasing signal detection at low levels of stimulation. In addition, specificity is encoded by the oscillation frequency: rapid oscillations stimulate all three transcription factors, whereas infrequent oscillations activate only NF-kappaB. The genes encoding the cytokines interleukin (IL)-2 and IL-8 are also frequency-sensitive in a way that reflects their degree of dependence on NF-AT versus NF-kappaB. Our results provide direct evidence that [Ca2+]i oscillations increase both the efficacy and the information content of Ca2+ signals that lead to gene expression and cell differentiation.

Calcium↗
PubMed1998

Kinetics of multivalent antigen DNP-BSA binding to IgE-Fc epsilon RI in relationship to the stimulated tyrosine phosphorylation of Fc epsilon RI.

Multivalent DNP-BSA is commonly used to cross-link anti-DNP IgE bound to Fc epsilon RI to stimulate cellular responses, although key features of the binding process are unknown. Fluorescence quenching can be used to study the kinetics of DNP-BSA binding to FITC-IgE. We observe that DNP-BSA binds more slowly to IgE than does an equimolar amount of a monovalent DNP ligand, suggesting that the average effective number of DNP groups per BSA is less than one. The binding data are well described by a transient hapten exposure model in which most of the DNP groups are unavailable for binding but have some probability of becoming exposed and available for binding during the time of the binding measurement. Additional experiments indicate that, for suboptimal to optimal concentrations of DNP-BSA, most of the FITC fluorescence quenching on the cell surface is due to cross-linking events. With these concentrations at 15 degrees C, the kinetics of FITC fluorescence quenching by DNP-BSA correlates with the kinetics of DNP-BSA-stimulated tyrosine phosphorylation of Fc epsilon RI. At 35 degrees C, the phosphorylation kinetics are biphasic during the time period in which cross-linking continues to increase. Our results establish a quantitative relationship between the time-course for cross-linking by multivalent Ag and Fc epsilon RI-mediated signaling, and they provide the means to predict the kinetics of cross-linking under a wide variety of conditions.

Animals↗
PubMed1998

Alteration of alpha1-adrenoceptor subtypes in aortas of 12-month-old spontaneously hypertensive rats.

Alterations in alpha1-adrenoceptor subtypes in aortas from 12-month-old spontaneously hypertensive rats (SHR) were studied in functional studies and RNase protection assays. The norepinephrine-induced contraction, including maximum response and pD2 values, was not significantly different between the SHR and age-matched Kyoto Wistar (WKY) rats. The pA2 values of the alpha1D-adrenoceptor subtype-selective antagonist BMY7378 (8-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-8-azaspiro(4.5)dec ane-7,9-dionedihydrochloride) were increased from 8.10 +/- 0.12 in WKY rats to 8.45 +/- 0.13 in SHR (P < 0.05). The pA2 values of the alpha1A-adrenoceptor subtype-selective antagonist RS-17053 (N-[2-(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro-alpha,alpha-dim ethyl-1H-indole-3-ethanamine hydrochloride) were reduced from 8.52 +/- 0.20 in WKY rats to 7.82 +/- 0.18 in SHR (P < 0.05), whereas the pA2 values of the alpha1A/alpha1D-adrenoceptor subtype-selective antagonist WB4101 (2-(2,6-dimethoxphenoxyethyl)-aminomethyl-1,4 benzodioxane) were not significantly different between WKY rats and SHR (9.05 +/- 0.22 versus 9.27 +/- 0.15, P > 0.05). Preincubation of preparations in 50 microM chloroethylclonidine for 30 min irreversibly inhibited the norepinephrine-induced response more profoundly in aortas from SHR than in aortas from WKY rats. The results of RNase protection assays showed that mRNAs for alpha1A- and alpha1B-adrenoceptor subtypes were decreased and that mRNA for the alpha1D-adrenoceptor subtype was increased in aortas from SHR compared with WKY rats. The results suggested that the alpha1A-adrenoceptor subtype was decreased and the alpha1D-adrenoceptor subtype was increased in aortas of 12-month-old SHR.

Adrenergic alpha-Antagonists↗
PubMed1998

Alteration in L-DOPA evoked dopamine and DOPAC output under conditions of impaired vesicular dopamine storage.

We examined the effect of L-dihydroxyphenylalanine (L-DOPA) infusion in vitro upon dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) output from superfused corpus striatum of vehicle and reserpine or tetrabenazine (TBZ) treated male rats. Specifically, we tested the effects of two 20-min infusions of L-DOPA (5 uM) upon DA and DOPAC output (pg/mg/min) in reserpine (5 mg/kg, i.p., 24 hours before sacrifice; n=11), TBZ (30 mg/kg, i.p. 1 hour before sacrifice; n=8) or vehicle (n=21) treated rats. There was an overall significantly higher L-DOPA evoked DA output from the vehicle (12.22+/-1.74) versus reserpine (4.39+/-2.40) (p < 0.05), but not TBZ (9.16+/-2.81) treated rats. In addition, the DA response to the second L-DOPA infusion was significantly increased over that of the first response in the vehicle (9.40+/-2.11 vs. 15.04+/-2.78) (p < 0.05), but not reserpine or TBZ treated rats. The overall DOPAC outputs did not achieve a statistically significant difference among all treatment groups. However, the DOPAC outputs following the second L-DOPA infusion were significantly reduced in reserpine (41.15+/-6.10 vs. 20.27+/-4.54) and TBZ (21.38+/-4.41 vs. 10.87+/-2.36) (both p < 0.05), but not vehicle (28.99+/-4.00 vs. 24.91+/-4.78) treated rats. We conclude that: 1) the storage capacity of DA neurons is one of the important elements involved in affecting L-DOPA's effects upon DA and DOPAC output, 2) the shunting of storage to metabolism may represent a common characteristic in impaired nigrostriatal dopaminergic system, and 3) TBZ may operate differently from reserpine in the nigrostriatal dopaminergic system.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1998

Human preembryo development on autologous endometrial coculture versus conventional medium.

OBJECTIVE: To evaluate the effect of autologous endometrial coculture versus conventional medium on preembryo development. DESIGN: Controlled systematic clinical study. SETTING: University-based IVF center. PATIENT(S): Women with a history of failed IVF-ET with poor preembryo quality. INTERVENTION(S): Patients underwent a luteal phase endometrial biopsy. The tissue then was digested enzymatically, and the stromal and glandular cells were separated by differential sedimentation rates. These cells were cultured to confluence, released, and then cryopreserved until the patient's IVF-ET cycle. All normally fertilized oocytes then were allocated systematically to growth on autologous endometrial coculture or conventional medium until transfer on day 3. MAIN OUTCOME MEASURE(S): Preembryo blastomere numbers and cytoplasmic fragmentation rates were measured. RESULT(S): Forty-two women underwent 44 cycles of IVF-ET. In the morning on day 3, the mean (+/-SD) number of blastomeres and cytoplasmic fragments per preembryo on coculture compared with conventional medium was 5.9+/-1.5 versus 5.5+/-1.4 and 21%+/-13% versus 24%+/-11. At transfer the mean (+/-SD) number of blastomeres per preembryo on coculture was 7.4+/-1.3 versus 6.7+/-1.9 on conventional medium. CONCLUSION(S): There was a significant improvement in the mean (+/-SD) number of blastomeres per preembryo and decrease in the fragmentation rate for preembryos on autologous endometrial coculture compared with noncocultured preembryos from the same patient.

Adult↗
PubMed1998

Structure-activity studies of fluoroalkyl-substituted gamma-butyrolactone and gamma-thiobutyrolactone modulators of GABA(A) receptor function.

Dihydro-2(3H)-furanones (gamma-butyrolactones) and dihydro-2(3H)-thiophenones (gamma-thiobutyrolactones) containing fluoroalkyl groups at positions C-3, C-4, and C-5 of the heterocyclic rings were prepared. The anticonvulsant/convulsant activities of the compounds were evaluated in mice. Brain concentrations of the compounds were determined and the effects of the compounds on [35S]-tert-butylbicyclophosphorothionate ([35S]TBPS) binding to the picrotoxin site on GABAA receptors were investigated. The effects of the compounds on GABAA receptor function were studied using electrophysiological methods and cultured rat hippocampal neurons. Fluorination at C-3 results in either subtle or pronounced effects on the pharmacological activity of the compounds. When hydrogens are replaced with fluorines at the methylene carbon of an ethyl group, as in 3-(1,1-difluoroethyl)dihydro-3-methyl-2(3H)-furanone (1), the anticonvulsant actions of the compound are not much changed from those found for the corresponding alkyl-substituted analogue. In marked contrast, fluorination at the methyl carbon of the ethyl group, as in dihydro-3-methyl-3-(2,2,2-trifluoroethyl)-2(3H)-furanone (3), produces a compound having convulsant activity. This convulsant activity seems to be due to an increased affinity of the compound for the picrotoxin site on GABAA receptors caused by an interaction that involves the trifluoromethyl group. Results obtained with gamma-butyrolactones containing either a 3-(1-trifluoromethyl)ethyl or a 3-(1-methyl-1-trifluoromethyl)ethyl substituent indicate that the interactions of the trifluoromethyl group with the picrotoxin binding site are subject to both stereochemical and steric constraints. Sulfur for oxygen heteroatom substitution, as in the corresponding gamma-thiobutyrolactones, affects the type (competitive, non-competitive, etc.) of binding interactions that these compounds have with the picrotoxin site in a complex manner. Fluorination of alkyl groups at the C-4 and C-5 positions of gamma-butyrolactones having convulsant activity increases convulsant potency.

4-Butyrolactone↗
PubMed1998

Improving the fixation method for preimplantation genetic diagnosis by fluorescent in situ hybridization.

PURPOSE: Our purpose was to modify a fixation method using Tween-20 and HCl (TH) and to compare it with a protocol using methanol and acetic acid (MA) for the improvement of preimplantation genetic diagnosis by fluorescence in situ hybridization (FISH). METHODS: Single blastomeres were allocated to either the TH or the MA procedure. The two methods were compared to evaluate efficiency of fixation and the intensities of FISH signals. RESULTS: With the TH method, 123 (93.9%) of 131 blastomeres were fixed, while only 95 (78.5%) of 121 were fixed with MA. Average scores for the intensity of FISH signals were significantly stronger for TH than for MA (P < 0.05). There was also a significant difference in signal intensity scores between the two methods for type-3 nuclei. CONCLUSIONS: Our results indicate that not only are fewer nuclei lost during fixation but also stronger FISH signals can be obtained with the TH method. Thus, modified TH can improve the overall efficiency of preimplantation genetic diagnosis.

Acetic Acid↗
PubMed1998

Detection of Neisseria gonorrhoeae infection by ligase chain reaction testing of urine among adolescent women with and without Chlamydia trachomatis infection.

BACKGROUND AND OBJECTIVES: Culture, the conventional method for detection of Neisseria gonorrhoeae, requires invasive sampling and stringent specimen transport conditions. The recently developed ligase chain reaction test (LCR; Abbott Laboratories; North Chicago, IL) allows noninvasive sampling and stable transport conditions, but has not been evaluated with specimens from adolescent populations. GOAL OF THIS STUDY: To perform a comparative evaluation of a commercial LCR test and culture for the diagnosis of N. gonorrhoeae in adolescent women. STUDY DESIGN: Urine and endocervical swab specimens from 330 teenage women seen in two public health adolescent clinics were tested by LCR and culture. For resolution of discordant results, a polymerase chain reaction (PCR) test was developed that directly amplifies N. gonorrhoeae DNA from urine samples processed for LCR. RESULTS: Thirty-one of 330 (9.4%) cervical specimens were culture-positive for N. gonorrhoeae, and 30 of 330 (9.1%) urine specimens were positive by LCR. After resolution of 13 discordant results, the sensitivity, specificity, and positive and negative predictive values of LCR for urine were 88.2%, 100%, 100%, 98.7%, respectively, and for culture of endocervical specimens were 82.3%, 98.9%, 90.3% and 98%, respectively. CONCLUSIONS: Although more expensive than culture, LCR offers a sensitive means for the detection of N. gonorrhoeae in urine samples and may be useful for this purpose in settings where pelvic examinations are difficult to perform and simultaneous detection of N. gonorrhoeae and Chlamydia trachomatis is advantageous.

Adolescent↗
PubMed1998

Histamine induces nuclear factor of activated T cell-mediated transcription and cyclosporin A-sensitive interleukin-8 mRNA expression in human umbilical vein endothelial cells.

The nuclear factor of activated T cells (NFAT) mediates a cyclosporin A (CsA)- and FK506-suppressible transcriptional program in lymphocytes after antigen-stimulated phospholipase C activation. Nonlymphoid cells also express NFAT isoforms, raising the possibility that these isoforms can be regulated by other extracellular stimuli. This study sought to determine whether histamine can trigger NFAT-mediated transcription in human umbilical vein endothelial cells (HUVEC), using a retrovirus-based luciferase reporter driven by a well characterized, NFAT-specific enhancer. Luciferase levels are induced up to 60-fold over basal levels after costimulation of HUVEC with Ca2+-mobilizing drugs and a phorbol ester, a response that is 20-fold greater than that observed when HUVEC are stimulated with either drug alone. These synergistic responses are inhibited in cells treated with CsA. CsA and FK506 also inhibit the luciferase response to histamine, indicating that histamine can induce NFAT-mediated transcription in HUVEC. To identify candidate genes in HUVEC that might be regulated by NFAT, the expression of several chemokine mRNAs was measured after histamine treatment. Of the mRNAs tested, only those encoding monocyte chemotactic protein-1 (approximately 2-fold over basal) and interleukin-8 (approximately 6-fold over basal) are induced by histamine; both of these responses are suppressed by CsA and FK506. The H1 histamine receptor antagonist chlorpheniramine, but not the H2 receptor antagonist ranitidine, blocks the effects of histamine in this preparation. These data provide the first evidence for a physiological inducer of NFAT-mediated transcription in endothelial cells and support the hypothesis that NFAT participates in H1 histamine receptor-induced interleukin-8 gene expression.

Cell Line↗
PubMed1998

Stimulated release of fluorescently labeled IgE fragments that efficiently accumulate in secretory granules after endocytosis in RBL-2H3 mast cells.

Sensitization of RBL-2H3 mast cells with monomeric fluorescein-5-isothiocyanate (FITC)-labeled immunoglobulin E (IgE) results in slow but highly efficient accumulation of labeled IgE fragments in a pool of acidic peripheral vesicles that are visible by fluorescence microscopy after raising endosomal pH with ammonium chloride. Stimulation of cells containing these FITC-IgE fragments by aggregation of high affinity receptors for IgE (FcepsilonRI) or by Ca2+ ionophore and phorbol 12-myristate 13-acetate results in release of FITC fluorescence from the cells, which can be monitored continuously with a spectrofluorometer. The fluorescence release process corresponds to cellular degranulation: it is prevented under conditions that prevent stimulated beta-hexosaminidase release, and these two processes exhibit the same antigen dose-dependence and kinetics. Pulse-chase labeling reveals that aggregation of FITC-IgE bound to FcepsilonRI at the cell surface causes internalization and delivery to the regulated secretory vesicles with a high efficiency similar to monomeric IgE-FcepsilonRI, but more rapidly. Binding of Cy3-modified IgE to FcepsilonRI results in labeling of the same secretory vesicles as in FITC-IgE-sensitized cells, and these Cy3-labeled vesicles can be observed by fluorescence microscopy without neutralization of intracellular compartments. Simultaneous three-photon microscopy of serotonin fluorescence and two-photon microscopy of Cy3 fluorescence reveals that these Cy3-labeled vesicles coincide with serotonin-labeled secretory granules. After stimulation of the cells via aggregation of IgE-FcepsilonRI or addition of Ca2+ ionophore and phorbol 12-myristate 13-acetate, depletion of the Cy3 label from the intracellular vesicles is observed with confocal microscopy. These results provide strong evidence for the lysosomal nature of secretory granules in these cells. In addition, they provide the basis for a direct, real-time method for monitoring single cell degranulation.

Animals↗
PubMed1998

Protective immunization of monkeys with BCG or BCG plus heat-killed Mycobacterium leprae: clinical results.

Rhesus and sooty mangabey monkeys (RM and SMM) were vaccinated and boosted with BCG or BCG + low dose (LD) or high dose (HD) heat-killed Mycobacterium leprae (HKML). One group was not vaccinated. Except for a group of controls, all monkeys were challenged with live M. leprae. All animals were studied longitudinally to determine antileprosy protective efficacy. BCG reduced the numbers of RM with histopathologically-diagnosed leprosy by 70% and slowed and ameliorated the appearance of symptoms. BCG + LDHKML reduced the number of RM with leprosy by 89% and BCG + HDHKML by 78%. BCG did not protect SMM from developing leprosy, but disease progress was slowed; disease in SMM was exacerbated by the addition of HKML to the vaccine. RM, as a species, are prone to paucibacillary (PB) forms of leprosy, whereas SMM are prone to multibacillary (MB) forms. Thus, BCG vaccination offers significant protection from clinical disease and slows/ameliorates the rate of progression/degree of disease at the PB end and appears to at least ameliorate symptoms at the MB end of the leprosy spectrum. BCG + HKML protects at the PB end and exacerbates disease progress at the MB end of the leprosy spectrum.

Animals↗
PubMed1998

Impaired responses to Mycobacterium leprae antigens in rhesus monkeys experimentally inoculated with simian immunodeficiency virus and M. leprae.

Seven of eight rhesus monkeys (RM) coinfected with simian immunodeficiency virus (SIV) and Mycobacterium leprae harboured acid-fast bacilli (AFB) at sites of dermal inoculation and/or at disseminated sites at times of humane sacrifice (up to 270 days post-M. leprae inoculation) due to SIV-induced debilitation or, in one long term survivor's case, to date over 3 years post-M. leprae inoculation. Detectable AFB were cleared in biopsies of inoculation sites of RM inoculated with M. leprae alone after 63 days postinoculation; these sites have, so far, remained AFB-negative, thereafter. Compared to animals infected with M. leprae alone, RM coinfected with SIV plus M. leprae showed: 1, completely suppressed serum antibody responses to M. leprae-specific PGL-I antigen, but strong anti-SIV Gp120 antibody responses; 2, impaired sensitization of blood mononuclear cells (MNC) to in vitro recognition of M. leprae-specific antigens in blastogenic stimulation assays; 3, impaired in vitro responses of blood MNC to nonspecific (ConA) blastogenic stimuli; and 4, early post-M. leprae inoculation, there was a significant incremental diminution of percentages of blood CD4+CD29+ T-cells in addition to the existing SIV-induced diminished percentages of CD4+CD29+ T-cells. The results indicate that humoral and cellular immune responses to M. leprae antigens are compromised in M. leprae-inoculated RM previously infected with SIV. These results provide an immunologic basis for the demonstration of enhanced M. leprae persistence or leprosy susceptibility in SIV-M. leprae coinfected RM.

Animals↗
PubMed1998

Experimental leprosy in rhesus monkeys: transmission, susceptibility, clinical and immunological findings.

A total of 46 Rhesus monkeys (RM) was inoculated with Mycobacterium leprae (ML) and followed clinically and immunologically for extended periods. Twenty-one (45.7%) of the RM developed leprosy spanning the known leprosy spectrum, with six of 21 (28.6%) having disease in the borderline lepromatous to lepromatous area of the spectrum. RM with paucibacillary forms of leprosy produced predominantly IgG anti-phenolic glycolipid (PGL-I) antibodies and positive lepromin skin test and/or in vitro blastogenesis responses; IgM anti-PGL-I predominated in animals with BB-LL leprosy and correlated with negative immune responses to lepromin. IgG anti-PGL-I antibodies persisted in a number of RM for several years without histopathological evidence of leprosy, suggesting possible persisting subclinical infection. The data show that RM are a valuable model for the study of leprosy. Eleven of the 46 RM were inoculated with ML from sources infected with simian immunodeficiency virus (SIV), the monkey counterpart to the human immunodeficiency virus (HIV). The possible effect of SIV on the clinical outcome of ML infection could not be determined due to insufficient numbers of animals to yield statistically significant results.

Animals↗
PubMed1998

[An endometrium morphometry study on ovariectomized rats subjected to nilestriol and estradiol replalcement therapies].

This study was designed to evaluate the effect of estrogen on rat endometrium and compare the results of Nilestriol and Estradiol replacement therapies for preventing osteoporosis in ovariectomized rats. Forty 4-month old SD female rats were randomly divided into four groups, namely sham operation, bilateral ovariectomy, ovariectomy plus supplementary ethinyl estradiol (0.2 microgram/100 g B. W. qd x 5), and ovariectomy plus supplementary Nilestriol (0.15 mg/100 g B. W. once a week). Computerized image analyzer was used to evaluate the endomitrial pathological changes 10 weeks later. The results showed an atrophied endometrium in ovariectomized group, a slightly proliferative endometrium in Nilestriol treated group, and a markedly proliferative endometrium with local atypical hyperplasia in estradiol treated group. The difference between group 3 and group 4 in morphometry was significant (P < 0.5). These suggest the relative safety of Nilestriol replacement therapy for preventing menopausal osteoporosis.

Animals↗
PubMed1998

[c-erbB2 gene amplification in human primary epithelial ovarian cancer and its clinical significance].

OBJECTIVE: To study c-erbB2 gene amplification in human primary epithelial ovarian cancer and its clinical significance. METHODS: One hundred forty nine samples of primary epithelial ovarian tumors, including 34 beign tumors, 7 borderline tumors and 108 carcinoma, were studied for c-erbB2 gene amplification by Southern blot analysis. RESULTS: c-erbB2 gene amplification was detected in 35 (32.4%) of the 108 cases with primaey epithelial ovarian carcinoma, while all cases with beign tumors and borderline lesions were negative (P < 0.001). There was a strong correlation between c-erbB2 gene amplification and FIGO stage of human ovarian carcinoma (P = 0.026), degree of cell differentiation (P = 0.011) and the size of residual tumor (P < 0.001). Univariate and multivariate analysis showed that c-erbB2 gene amplification was an independent prognostic factor. The average 3-year survival rate was 28.4% in patients with gene amplification and 57.7% in patients without gene amplification(P = 0.016). CONCLUSION: c-erbB2 gene amplification occurs almost in 1/3 of the patients with ovarian carcinoma examined. Ovarian carcinoma with c-erbB2 gene amplification is highly malignant and associated with poor prognosis.

Adult↗
PubMed1998

Presynaptic changes of neuromuscular transmission in mice induced by passive transfer of plasma with anti-presynaptic membrane receptor antibodies from a patient with myasthenia gravis.

Electrophysiological studies were conducted in three groups of mice to determine the possible involvement of the antibodies to presynaptic membrane receptor (PsmR), a beta-bungarotoxin (beta-BuTX) binding protein, in the pathogenesis of myasthenia gravis (MG). Mice were untreated (untreated group, n = 8) or were injected (i.p.) with blood plasma from a MG patient, which contained antibodies to PsmR, at a dose of 1 ml per day for more than 2 months (MG plasma group, n = 12) or with plasma from healthy subjects (normal plasma group, n = 10). Prior to plasma injection, cyclophosphamide was given at 300 mg/kg (i.p.) to all three groups. About three weeks after plasma injection, most mice of the MG plasma group became less mobile in comparison with those of the two control groups. Electrophysiological recording showed three main changes in the MG plasma group: (1) the increase in the frequency of miniature endplate potentials (mEPPs) induced by Krebs solution with high K+ concentration (17.5 mM) was significantly lowered, which was confirmed in mice injected with IgG (50 mg per day) from this patient for two days; (2) the quantal content of EPP was decreased; and (3) the decrement in the amplitude of a train EPP (50 Hz) was quickened. Our results suggest that this experimental model is different from that of Lambert-Eaton myasthenic syndrome and that antibodies to PsmR may also be involved in the pathogenesis of MG.

Animals↗