[A comparative study between direct mechanical thrombectomy and bridging therapy in patients with atrial fibrillation associated anterior circulation large vessel occlusion stroke].

From January 1, 2015 to December 31, 2021, 94 patients who were diagnosed with atrial fibrillation (AF) associated anterior circulation large vessel occlusion stroke and underwent mechanical thrombectomy in the First Affiliated Hospital of Dalian Medical University were retrospectively collected, including 52 patients in the direct mechanical thrombectomy (dMT) group and 42 patients in the bridging therapy (BT) group. All patients received stent thrombectomy, and the BT group received intravenous thrombolytic therapy with alteplase within 4.5 hours.There were no significant differences in 7 d National Institute of Health Stroke Scale (NIHSS) score[12.0 (5.2, 42.0) vs 10.0 (6.0, 25.8)], incidence of hemorrhage transformation [44.2%(23/52) vs 45.2%(19/42)], symptomatic intracranial hemorrhage[11.5%(6/52) vs 11.9%(5/42)],90 d mortality[34.6% (18/52) vs 38.1% (16/42)]between the two groups(all P>0.05). The rate of 90 d good prognosis in dMT and BT groups was 36.5% (19/52) and 35.7% (15/42), respectively, and the difference was not statistically significant(OR=1.45, 95%CI: 0.39-3.37, P=0.805). The number of stent passes[2(1,3) vs 1(1,2)] and the vessel recanalization time [(81±41)min vs (57±29)min] in the BT subgroup of middle cerebral artery (MCA) occlusion were longer than those in the dMT group (both P<0.05).Therefore, direct thrombectomy has similar efficacy and safety as bridging therapy in the treatment of AF related anterior circulation large vessel occlusive stroke, which is worthy of further research and verification.

[Consistency analysis and clinical guiding significance of cytomegalovirus nucleic acid and antibody detections in patients with different clinical characteristics].

OBJECTIVE: To investigate the consistency of cytomegalovirus deoxyribo nucleic acid (CMV-DNA) and immunoglobulin M (IgM) antibody detections in patients with different clinical characteristics and their guiding value for clinical practice. METHODS: From December 2014 to November 2019, a total of 507 patients who were detected with both CMV-IgM and CMV-DNA were collected in Peking University International Hospital. Their general information, such as gender, age and clinical data, including the patient's diagnosis, medication, and outcome were also collected. The groups were stratified according to whether CMV-DNA was negative or positive, CMV-IgM was negative or positive, age, gender, and whether they received immunosuppressive therapy or not. The Pearson Chi-square test or Fisher's exact test was used for comparison of the rates between the groups. P < 0.05 means the difference is statisti-cally significant. RESULTS: Of the 507 patients submitted for examination, 55 (10.85%) were positive for CMV-DNA, 74 (14.60%) were positive for CMV-IgM, and 20 (3.94%) were positive for both CMV-DNA and CMV-IgM. Of the 55 patients with CMV-DNA positive, 37 were male, accounting for 67.27%. In addition, 25 patients were older than 60 years, accounting for 45.45% and 33 patients received immunosuppressive therapy, accounting for 60%. The rates were higher than that of CMV-DNA negative group, 47.35% (P=0.005), 68.14% (P=0.043), 46.02% (P=0.050), respectively. Of the patients with both CMV-DNA and IgM positive, 45% received immunosuppressive threapy, which was lower than that of CMV-DNA positive but IgM negative patients (68.57%, P=0.086), and also lower than CMV-DNA negative but IgM positive patients (68.52%, P=0.064). In the patients with both CMV-DNA and IgM positive, 91.67% showed remission after receiving ganciclovir, whereas in the patients with CMV-DNA positive but IgM negative, the rate was only 60% (P=0.067). CONCLUSION: CMV-IgM antibody detection is affected by age, gender, and immune status. It is not recommended to use CMV-IgM alone to determine CMV infection in patients with immunosuppressive status and those older than 60 years. CMV-DNA and CMV-IgM combined detection may help to predict patients' immune status and outcomes of antiviral therapy.

[Association of lipoprotein a in early pregnancy with gestational diabetes mellitus: a prospective cohort study].

Objective: To investigate the association of lipoprotein a (Lpa) in early pregnancy with gestational diabetes mellitus (GDM) risk. Methods: A total of 445 pregnant women in 12-14 gestational weeks from "Maternal Key Nutritional Factors and Offspring's Atopic Dermatitis" cohort were included in this study. The demographic characteristics of participants were collected by using questionnaires, and the fasting glucose and lipids levels in early pregnancy were measured. The results of oral glucose tolerance test (OGTT) between 24-28 gestational weeks were recorded. Multivariate logistic regression model was applied to analyze the association of Lpa with GDM by calculating the OR and 95%CI after adjustment for covariates. Results: The incidence number of GDM was 78 (17.5%). The Lpa level in pregnant women with GDM was significantly higher than that in pregnant women without GDM [105.5 (92.0, 122.0) vs. 97.0 (87.0, 109.0) mg/L], P<0.05. Lpa was significantly associated with GDM risk [OR (95%CI) =1.21(1.08-1.36) per 10 mg/L], P<0.05. The association was still significant after adjustment for covariates including age, gestational weeks et al, the adjusted OR was 1.14 (95%CI: 1.01-1.30), P=0.03. Conclusions: The elevation of Lpa in early pregnancy is one of risk factor for GDM. Maintaining normal Lpa level during early pregnancy can benefit early prevention of GDM and offspring health.

Research on the relations between the variation of miRNA-184 before and after treatment of acute myocardial infarction and prognosis.

OBJECTIVE: Several miRNAs have been shown to be released into the circulation and play roles during acute myocardial infarction (AMI). This study aimed at detecting the variation of miRNA-184 before and after treatment of acute myocardial infarction and assessing its prognostic value. PATIENTS AND METHODS: 72 AMI patients participated in the study, alongside 10 patients with stable coronary disease and 10 healthy volunteers for comparison. The expression levels of miRNA-184 were measured in AMI patients at 6 h, 12 h, 48 h, 7 d, and 14 d after the onset of symptoms, using blood samples and an RT-PCR method. The levels were compared to single-time levels in the other two groups of individuals. The correlations between the N-terminal pro-brain natriuretic peptide (NT-proBNP) and parameters of the ventricular function (LVEDd and LVEF) and miRNA-184 levels were analyzed taking samples during a one-month follow-up visit. Finally, the correlation between the occurrence rate of major adverse cardiac effects (MACE) and miRNA-184 levels was analyzed evaluating the occurrence of MACE at a one-year follow-up visit. RESULTS: The expression levels of miRNA-184 (6h) were significantly higher than those of the other two groups (p < 0.05). The levels reached a peak 24 h after the onset of symptoms and fell back to normal after 7 to 14 days (at which point the levels were no different than the levels in the other two groups). NT-proBNP and left ventricular end-diastolic diameter (LVEDd) were significantly lower after treatment, whereas the left ventricular ejection fraction (LVEF) increased significantly (p < 0.05). After a relevant Pearson analysis the expression level of miRNA-184 mRNA was positively correlated with ∆NT-proBNP (before and after treatment) (p < 0.05), with ∆LVEDd (before and after treatment) and with ∆LVEF (before and after treatment) (p < 0.05). Finally, 22 cases (36%) of major adverse cardiac events, MACE, were found in AMI patients, and the expression levels of miRNA-184 of the MACE group were significantly higher than those of the non-MACE group at each time point (p < 0.05). CONCLUSIONS: miRNA-184 shows a dynamic evolution before and after percutaneous coronary intervention (PCI) treatment of AMI, and it is closely correlated with recent ventricular remodeling indexes and a future occurrence rate of MACE.

Renal clear cell carcinoma: diffusion tensor imaging diagnostic accuracy and correlations with clinical and histopathological factors.

AIM: To investigate whether diffusion tensor imaging (DTI) can be used to assess renal clinical histopathology, including the nuclear grade (NG), cell density (CD), and the presence of ki-67. MATERIALS AND METHODS: Thirty patients were enrolled in the study and were confirmed at surgical histopathology to have clear cell renal cell carcinoma (CCRCC). For DTI, a coronal echo-planar imaging sequence was performed (1400 ms repetition time, 76 ms echo time, diffusion direction=6, number of excitations=4; b=0 and 800 s/mm2, 6 mm section thickness with no intersection gap). CD and the presence of ki-67 were compared between the different NGs. Correlations between apparent diffusion coefficients (ADCs), E1, fractional anisotropy (FA), CD, and ki-67 were evaluated. RESULTS: ADC, E1, and FA values are important tools used to identify NG. The cut-off values were 1.003×10-3 mm2/s, 1.277×10-3 mm2/s, and 0.218 mm2/s, respectively. The difference between high- and low-grade CD was significant (t=-4.50, p<0.05). Similarly, a significant difference between high and low grade was also found in ki-67 (t=-4.03, p<0.05). ADC, E1, and FA values were decreased with increased CD; a significant negative correlation was found (r=-0.796, -0.865, and -0.996, respectively). Significant negative correlations between ADC, E1, and FA values, and ki-67 were found (r=-0.739, -0.826, and -0.876, respectively). CONCLUSIONS: DTI can be used to non-invasively assess CCRCC.

[Efficacy of intravenous thrombolysis in acute ischemic stroke with hyperdense middle cerebral artery sign].

Objective: To observe the efficacy and safety of recombinant tissue-type plasminogen activator (rtPA) intravenous thrombolysis (IVT) in the treatment of acute cerebral infarction with hyperdense middle cerebral artery sign (HMCAS). Methods: Acute cerebral infarction patients with HMCAS from July 2010 to November 2015 at the First Affiliated Hospital of Dalian Medical University were collected.These patients were divided into two groups depending on whether they received IVT or not.The Nation Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) were used to evaluate early and long-time therapeutic effects.Efficacy and safety were compared between the two groups. Results: A total of 93 patients were eligible for the analysis, with 45 cases in IVT group and 48 cases in non-IVT group.As time went by, NIHSS score in IVT group showed significant downward trend than the non-IVT group.The rate of patients with good outcome in IVT group was higher than that in non-IVT group (P<0.05). The rate of hemorrhage transformation (HT) in IVT group and non-IVT group was 35.6% (16/45) and 10.4% (11/48), respectively, and the difference was statistically significant (P<0.05). While no statistically significant difference was found about the rate of symptomatic intracranial hemorrhage (sICH) (8.9% vs 2.1%, P>0.05) and mortality (33.3% vs 27.1%, P>0.05) between these two groups.Logistic regression analysis identified relativity between IVT treatment and good outcome (P<0.05), hemorrhage transformation (P<0.05), rather than mortality (P>0.05). Conclusions: Intravenous thrombolysis with rt-PA is an effective and safe treatment for most acute ischemic stroke patients with HMCAS and can promote early neurologic improvement and significantly improve long-term functional prognosis.Although Ⅳ thrombolysis can increase the risk of overall HT, it does not add risk in sICH and mortality.

[Analysis of clinical outcomes of different embryo stage biopsy in array comparative genomic hybridization based preimplantation genetic diagnosis and screening].

Objective: To evaluate the efficiency of the application of array comparative genomic hybridization (array-CGH) in preimplantation genetic diagnosis or screening (PGD/PGS), and compare the clinical outcomes of different stage embryo biopsy. Methods: The outcomes of 381 PGD/PGS cycles referred in the First Affiliated Hospital of Nanjing Medical University from July 2011 to August 2015 were retrospectively analyzed. There were 320 PGD cycles with 156 cleavage-stage-biopsy cycles and 164 trophectoderm-biopsy cycles, 61 PGS cycles with 23 cleavage-stage-biopsy cycles and 38 trophectoderm-biopsy cycles. Chromosomal analysis was performed by array-CGH technology combined with whole genome amplification. Single embryo transfer was performed in all transfer cycles. Live birth rate was calculated as the main clinical outcomes. Results: The embryo diagnosis rate of PGD/PGS by array-CGH were 96.9%-99.1%. In PGD biopsy cycles, the live birth rate per embryo transfer cycle and live birth rate per embryo biopsy cycle were 50.0%(58/116) and 37.2%(58/156) in cleavage-stage-biopsy group, 67.5%(85/126) and 51.8%(85/164) in trophectoderm-biopsy group (both P<0.01). In PGS biopsy cycles, the live birth rate per embryo transfer cycle and live birth rate per embryo biopsy cycle were the same as 34.8%(8/23) in cleavage-stage-biopsy group, the same as 42.1%(16/38) in trophectoderm-biopsy group (both P>0.05). Conclusions: High diagnosis rate and idea live birth rate are achieved in PGD/PGS cycles based on array-CGH technology. The live birth rate of trophectoderm-biopsy group is significantly higher than that of cleavage-stage-biopsy group in PGD cycles; the efficiency of trophectoderm-biopsy is better.

[Effect of intravenous thrombolysis with recombinant tissue type plasminogen activator (rt-PA) in different time windows on acute cerebral infarction patients with atrial fibrillation].

OBJECTIVES: To observe the intravenous thrombolysis effect of rt-PA in different time windows of acute cerebral infarction with atrial fibrillation(AF). METHODS: Acute cerebral infarction patients who accepted the intravenous thrombolysis treatment with AF from January 2012 to December 2015 were included.According to the time from onset to intravenous thrombolysis, patients were divided into two groups: thrombolysis within 3 h and thrombolysis between 3-4.5 h. The Nation Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) were used to evaluate early and long-time therapeutic effects. The incidence of hemorrhagic infarction(HI), parenchymal hemorrhage(PH) and symptomatic intracranial hemorrhage(sICH) after thrombolysis within 24 hours were observed in the two groups. RESULTS: A total of 103 patients were included in the study, with 48 cases in thrombolysis within 3 h group and 55 cases in thrombolysis between 3-4.5 h group. After thrombolysis treatment, the 24-hour and 7-day NIHSS score of the two groups were significant lower than before treatment, and the difference was statistically significant(P<0.05). Compared between groups, 24-hour clinical efficacy of thrombolysis within 3 h group was better than that of thrombolysis between 3-4.5 h group, and the difference was statistically significant(P<0.05). There were no statistically significant differences between these two groups about 7-day and 90-day prognosis(P<0.05). The rate of PH in thrombolysis within 3 h group and thrombolysis between 3-4.5 h group is 6.3%(3/48) and 21.8%(12/55) individually, and the difference was statistically significant(P<0.05). While no statistically significant differences was found about the rate of HI(18.8% vs 32.7%, P>0.05) and sICH(8.3% vs 14.5%, P>0.05) between these two groups. CONCLUSIONS: For patients of acute cerebral infarction with AF, intravenous thrombolytic therapy by rt-PA within 3 h may contribute to a greatly improvement in a short time. Thrombolysis between 3-4.5 h increase the incidence of PH, but do not increase the incidence of sICH. There are no statistically significant differences between these two groups about 90-day favorable prognosis, indicating that thrombolysis between 3-4.5 h is safe and effective for acute cerebral infarction patients with AF.

Polycatechol nanosheet: a superior nanocarrier for highly effective chemo-photothermal synergistic therapy in vivo.

The integration of phototherapy and chemotherapy in a single system holds great promise to improve the therapeutic efficacy of tumor treatment, but it remains a key challenge. In this study, we describe our recent finding that polycatechol nanosheet (PCCNS) can be facilely prepared on a large scale via chemical polymerization at 4 °C, as an effective nanocarrier for loading high-density CuS nanocrystals as a photothermal agent. The resulting CuS/PCCNS nanocomposites exhibit good biocompatibility, strong stability, and a high photothermal conversion efficiency of ∼45.7%. The subsequent loading of anticancer drug doxorubicin (Dox) creates a superior theranostic agent with pH- and heat-responsive drug release, leading to almost complete destruction of mouse cervical tumor under NIR laser irradiation. This development offers an attractive theranostic agent for in vivo chemo-photothermal synergistic therapy toward biomedical applications.

The complete mitochondrial genome sequence of the dwarf blue sheep, Pseudois schaeferi haltenorth in China.

The dwarf blue sheep (Pseudois schaeferi haltenorth) belongs the subfamily Caprinae, which is distributed in Sichuan, Tibet, Yunnan, and Qinghai in China. In this study, the complete mitochondrial genome of Pseudois schaeferi haltenorth was sequenced. The mitogenome was 16 741 bp in length, consisting of 13 protein-coding genes, 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and a non-coding control region (D-loop region). As in other mammals, most mitochondrial genes are encoded on the heavy strand, except for ND6 and eight tRNA genes which are encoded on the light strand. The overall base composition of the Pseudois schaeferi haltenorth is 33.54% A, 26.37% T, 26.91% C, and 13.18% G, A + T (59.91%) was higher than G + C (40.09%). The phylogenetic relationships was analyzed using the complete mitogenome sequence, results show that P. schaeferi haltenorth should be a different species differ from the Genus pseudois hodgson. These information provide useful data for further study on the protection of genetic resources and the taxonomy of Caprinae.

The complete mitochondrial genome sequence of the wild Huoba Tibetan sheep of the Qinghai-Tibetan Plateau in China.

The wild Huoba Tibetan sheep belongs to the subfamily Caprinae, which distributes in Huoba Town of Tibet Autonomous Region, China. In the present work, we report the complete mitochondrial genome sequence of wild Huoba Tibetan sheep for the first time. The total length of the mitogenome is 16 621 bp, consisting of 13 protein-coding genes, 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and a non-coding control region (D-loop region). As in other mammals, most mitochondrial genes are encoded on the heavy strand. Its overall base composition is A: 33.64%, T: 27.32%, C: 25.90%, and G: 13.14%, A + T (61.96%) was higher than G + C (39.04%). The phylogenetic relationships was analyzed using the complete mitogenome sequence, results show that wild Huoba Tibetan sheep should be a different species differ from the Ovis aries. These information provide an important data for further study on protection of genetic resources and the taxonomy of Caprinae.

Analysis of geographic and pairwise distances among sheep populations.

This study investigated geographic and pairwise distances among seven Chinese local and four introduced sheep populations via analysis of 26 microsatellite DNA markers. Genetic polymorphism was rich, and the following was discovered: 348 alleles in total were detected, the average allele number was 13.38, the polymorphism information content (PIC) of loci ranged from 0.717 to 0.788, the number of effective alleles ranged from 7.046 to 7.489, and the observed heterozygosity ranged from 0.700 to 0.768 for the practical sample, and from 0.712 to 0.794 for expected heterozygosity. The Wright's F-statistic of subpopulations within the total (FST) was 0.128, the genetic differentiation coefficient (GST) was 0.115, and the average gene flow (Nm) was 1.703. The phylogenetic trees based on the neighbor-joining method by Nei's genetic distance (DA) and Nei's standard genetic distance (DS) were similar. Sheep populations clustered into group 1 (Ta, M, L, H, O, G, and Q breeds) and group 2 (PD, WS, B, and T breeds). These results will have an important value applied and directive significance for sheep breeding in the future.

Limitation of high-resolution melting curve analysis for genotyping simple sequence repeats in sheep.

Variation in microsatellite or simple sequence repeat (SSR) loci has, until recently, relied heavily on the use of gel-based methods that can be both time consuming and difficult to genotype. Non gel-based systems are therefore important to increase simplicity and improve turn-around time without compromising assay sensitivity and accuracy. In this report, we assessed the latest of the non-gel-based methods, high-resolution melting (HRM) curve analysis. HRM is a technique that monitors exactly the decreasing fluorescence of intercalating dye in the process of dissociation of double-stranded DNA. The measurement immediately follows polymerase chain reaction in a one-step, closed-tube method. Four SSR loci of different complexity in sheep, namely MAF209, MCM140, CB226, and SRCRSP5, were assessed using the LightScanners System with LC Greens PLUS DNA binding dye. In order to improve the accuracy of genotyping, we applied internal oligo nucleotide calibrators while performing HRM. DNA polymorphisms were previously identified using capillary electrophoresis analysis (CE). The result showed that CE detected more genotypes than HRM in the same loci regardless of the level of polymorphism at the SSR loci. We demonstrate current limitations of the HRM method for the analysis of SSR loci.

Fasciculation and elongation protein zeta-1 (FEZ1) expression in reactive astrocytes in a rat model of Parkinson's disease.

AIMS: Fasciculation and elongation protein zeta-1 (FEZ1) is a critical regulator of dopaminergic neurone differentiation and dopamine release. However, to date, few studies evaluating the expression patterns of FEZ1 in Parkinson's disease (PD) have been reported. The aim of this study was to investigate the expression and cellular localization of FEZ1 in a rat model of PD and to explore the role of FEZ1 in PD pathogenesis. METHODS: Male Sprague-Dawley rats were randomly divided into two groups: a PD group and a sham group. A model of PD was established by injecting 6-Hydroxydopamine Hydrobromide (6-OHDA) into the right medial forebrain bundle of rats. Sham-lesioned rats were infused with equivalent amounts of saline and served as controls. The expression levels of FEZ1 mRNA and protein in striatum and substantia nigra were examined by real-time polymerase chain reaction (PCR) and by Western blot analysis respectively. Immunohistochemistry was performed to identify the cellular localization of FEZ1 in sham-lesioned and PD rats. RESULTS: Western blot and real-time PCR analyses demonstrated that FEZ1 was present in normal rat brain striatum and substantia nigra. After the 6-OHDA injection, FEZ1 expression gradually increased, peaked and then decreased. Immunohistochemical detection showed a shift of FEZ1 expression from tyrosine hydroxylase positive neurones in sham-lesioned rats to astrocytes in PD rats. CONCLUSIONS: Our results indicate that FEZ1 plays a role in the astrocytic protection of dopamine neurones and in the regulation of the neuronal microenvironment during the progression of PD.

ABT-737 synergizes with arsenic trioxide to induce apoptosis of gastric carcinoma cells in vitro and in vivo.

OBJECTIVE: This study investigated the potential synergistic effects of two inducers of apoptosis: the small molecule ABT-737 and arsenic trioxide (ATO). METHODS: Human gastric carcinoma cell lines SGC-7901 and MGC-803 were used to determine the effects of ABT-737 and ATO (alone or in combination) on cell proliferation and apoptosis in vitro. In vivo effects of these drugs were investigated in SGC-7901 solid tumours, grown in immunodeficient mice. RESULTS: ABT-737 and ATO inhibited proliferation and induced apoptosis in SGC-7901 and MGC-803 cells in concentration- and time-dependent manners, and showed a synergistic effect. ABT-737 disturbed the binding of B cell lymphoma (Bcl)-2 homologous antagonist killer and Bcl-extra large; ATO downregulated myeloid cell leukaemia (Mcl)-1 protein and upregulated Mcl-1short, the short splicing variant. ABT-737 and ATO significantly suppressed SGC-7901 xenograft growth, synergistically inhibited tumour growth and induced apoptosis in vivo. CONCLUSIONS: This study provides preclinical evidence that ABT-737 and ATO synergize to induce apoptosis of gastric carcinoma cells, suggesting that further investigation of these agents (as potential treatments for gastric cancer) is warranted.

Tracking presynaptic Ca2+ dynamics during neurotransmitter release with Ca2+-activated K+ channels.

Neurotransmitter release during action potentials is thought to require transient, localized [Ca2+]i as high as hundreds of micromolar near presynaptic release sites. Most experimental attempts to characterize the magnitude and time course of these Ca2+ domains involve optical methods that sample large volumes, require washout of endogenous buffers and often affect Ca2+ kinetics and transmitter release. Endogenous calcium-activated potassium (KCa) channels colocalize with presynaptic Ca2+ channels in Xenopus nerve-muscle cultures. We used these channels to quantify the rapid, dynamic changes in [Ca2+]i at active zones during synaptic activity. Confirming Ca2+-domain predictions, these KCa channels revealed [Ca2+]i over 100 microM during synaptic activity and much faster buildup and decay of Ca2+ domains than shown using other techniques.

Single-channel properties of BK-type calcium-activated potassium channels at a cholinergic presynaptic nerve terminal.

1. A high-conductance calcium-activated potassium channel (BK KCa) was characterized at a cholinergic presynaptic nerve terminal using the calyx synapse isolated from the chick ciliary ganglion. 2. The channel had a conductance of 210 pS in a 150 mM:150 mM K+ gradient, was highly selective for K+ over Na+, and was sensitive to block by external charybdotoxin or tetraethylammonium (TEA) and by internal Ba2+. At +60 mV it was activated by cytoplasmic calcium [Ca2+]i with a Kd of approximately 0.5 microM and a Hill coefficient of approximately 2.0. At 10 microM [Ca2+]i the channel was 50 % activated (V) at -8.0 mV with a voltage dependence (Boltzmann slope-factor) of 32.7 mV. The V values hyperpolarized with an increase in [Ca2+]i while the slope factors decreased. There were no overt differences in conductance or [Ca2+]i sensitivity between BK channels from the transmitter release face and the non-release face. 3. Open and closed times were fitted by two and three exponentials, respectively. The slow time constants were strongly affected by both [Ca2+]i and membrane potential changes. 4. In cell-attached patch recordings BK channel opening was enhanced by a prepulse permissive for calcium influx through the patch, suggesting that the channel can be activated by calcium ion influx through neighbouring calcium channels. 5. The properties of the presynaptic BK channel are well suited for rapid activation during the presynaptic depolarization and Ca2+ influx that are associated with transmitter release. This channel may play an important role in terminating release by rapid repolarization of the action potential.