[Association between volatile organic compounds and mortality risk of stroke]

Objective: To investigate the effect of volatile organic compounds (VOCs) exposure in the atmosphere on the risk of daily death from stroke in Guangzhou. Methods: Daily average concentrations of twelve atmospheric VOCs, meteorological factors, and daily deaths for stroke and its subtypes (including ischemic and hemorrhagic stroke) in Guangzhou from 2020 to 2021 were collected. The time-series Poisson generalized additive model was established to analyze the relationship between daily average concentrations of atmospheric VOCs and daily mortality from a stroke on different lag days. The season, gender, and age group further performed stratification analysis. Results: Toluene and n-pentane were associated with a higher mortality risk from stroke and its subtypes. For each interquartile range (IQR) increment in toluene concentration at lag0- 1 days, the RRs for mortality from stroke and hemorrhagic stroke were 1.060 (95%CI: 1.036-1.085) and 1.071 (95%CI: 1.030-1.113), respectively. For each IQR increment in n-pentane concentration, the RR for mortality from ischemic stroke was 1.064 (95%CI: 1.030-1.099). The effect estimates of VOCs may be higher during the cold season and among women and people aged ≥75 years. For each IQR increment in toluene concentration, the RRs for mortality risk of stroke in the cold season and women were 1.099 (95%CI: 1.056-1.143) and 1.085 (95%CI: 1.050-1.120), respectively. For n-pentane, the RR for death risk of stroke in people aged ≥75 years old was 1.072 (95%CI: 1.036-1.109). Results of sensitivity analysis showed that the effect estimates fluctuated less when PM2.5 and O3 were separately introduced for the two-pollutant model, as well as changing the degrees of freedom for covariates. Conclusions: This study suggests that VOCs may be an independent risk factor for daily mortality from stroke. Moreover, Toluene presented the most significant health impact.

[Research progress in association between endothelial dysfunction and periodontitis]

Vascular endothelium formulates the basic defense against cardiovascular diseases. Multiple factors such as inflammatory factors, oxidative stress and biological factors can cause endothelial dysfunction and be involved in the formation and development of cardiovascular diseases. In studies of recent years, accumulated evidences showed that periodontitis was an independent risk factor for cardiovascular events, and was related to vascular endothelial dysfunction. Periodontal therapy could improve the vascular endothelial function. In this paper, the epidemiological evidences of associations between periodontitis and vascular endothelial dysfunction in recent years were listed, and the possible mechanisms of periodontitis aggravating endothelial dysfunction were analyzed. The importance of periodontal intervention in improving endothelial function was emphasized. This will provide new ideas for further study about the relationship between periodontitis and cardiovascular diseases and for the prevention and treatment strategies.

ESMO expert consensus statements on the management of EGFR mutant non-small-cell lung cancer

The European Society for Medical Oncology (ESMO) held a virtual consensus-building process on epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancer in 2021. The consensus included a multidisciplinary panel of 34 leading experts in the management of lung cancer. The aim of the consensus was to develop recommendations on topics that are not covered in detail in the current ESMO Clinical Practice Guideline and where the available evidence is either limited or conflicting. The main topics identified for discussion were: (i) tissue and biomarkers analyses; (ii) early and locally advanced disease; (iii) metastatic disease and (iv) clinical trial design, patient's perspective and miscellaneous. The expert panel was divided into four working groups to address questions relating to one of the four topics outlined above. Relevant scientific literature was reviewed in advance. Recommendations were developed by the working groups and then presented to the entire panel for further discussion and amendment before voting. This manuscript presents the recommendations developed, including findings from the expert panel discussions, consensus recommendations and a summary of evidence supporting each recommendation.

Abstract P3-10-12: ERBB2 copy number analysis of invasive breast carcinoma using digital droplet PCR and targeted next-generation sequencing: A focus on 'non-classical' HER2 FISH groups using the 2018 ASCO/CAP HER2 testing guideline

Background: Non-classical HER2 FISH results were recently reclassified in the 2018 HER2 guidelines update, and concurrent IHC testing was recommended as part of additional workup to determine the final HER2 status in these groups. In this study, we explored the genomic landscape of HER2 FISH groups using digital droplet PCR (ddPCR) and targeted next-generation sequencing (NGS) on invasive breast carcinomas.

Methods: Fifty-one clinical samples with HER2 FISH and IHC results were included in our analysis and classified into FISH groups based on the updated 2018 ASCO/CAP HER2 testing guideline: (i) Group 1A with ratio ≥2 and signals/cell ≥6, (ii) Group 1B with ratio ≥2 and signals/cell ≥4 and <6, (iii) Group 2 with ratio ≥2 and signals/cell <4, (iv) Group 3 with ratio <2 and signals/cell ≥6, (v) Group 4 with ratio <2 and signals/cell ≥4 and <6, and (vi) Group 5 with ratio <2 and signals/cell <4. Formalin-fixed paraffin-embedded samples were analyzed using two ddPCR assays each targeting an exon in the ERBB2 tyrosine kinase domain (exon 19 and 21, respectively) and a 130-gene NGS-based assay. For ddPCR, ERBB2 amplification status was determined from ddPCR ratios by using a recently published algorithm (Otsuji et al. 2017). For targeted NGS, ERBB2 amplification was called when copy number gains were detected in the majority of exons in ERBB2 (>50% of exons).

Results: Mean ddPCR ratios varied amongst the different FISH groups (P < 0.0001). As expected, patients with Group 1A had the highest mean ddPCR ratios compared to those with other FISH findings (P < 0.0001). Furthermore, there was a correlation between ERBB2 ddPCR ratios and HER2 FISH ratios (ρe19 = 0.4435, P = 0.001 and ρe21 = 0.4644, P = 0.0006). Using ddPCR, ERBB2 amplifications were detected in all classically amplified Group 1A cases (5/5) and in none of the classically non-amplified Group 5 cases (0/12). Interestingly, ddPCR assays called ERBB2 amplification in four cases with non-classical results: one in Group 2 (1/6), two in Group 3 (2/6), and one in Group 4 (1/17), including two cases in Groups 3 and 4 which also showed concomitant HER2 overexpression by IHC (3+). Similarly, targeted NGS revealed ERBB2 amplification in all Group 1A cases (5/5) and in none of the Group 5 cases (0/12). Furthermore, NGS detected amplification in three non-classical cases: one in Group 1B (1/5), one in Group 3 (1/6), and one in Group 4 (1/17), including one case in Group 1B which was not called amplified by ddPCR. Notably, the three cases with amplification by NGS were the only three cases in the non-classical groups with HER2 overexpression by IHC. Overall, there was a strong concordance between ERBB2 amplification status by ddPCR/NGS and HER2 overexpression by IHC (κe19 = 0.79, κe21 = 0.92, κNGS = 1.0).

Conclusion: ERBB2 amplification using ddPCR and NGS is correlated with HER2 overexpression in both classical and non-classical FISH groups, thus providing genomic evidence to support the recent recommendation for concurrent IHC testing in cases with unusual FISH results. Our findings also highlight a potential role of ddPCR and targeted NGS in the workup of challenging HER2 cases.

Citation Format: Yang S-R, Bouhlal Y, De La Vega FM, Ballard M, West RB, Sibley RK, Kuo CJ, Vilborg A, Allison KH. ERBB2 copy number analysis of invasive breast carcinoma using digital droplet PCR and targeted next-generation sequencing: A focus on 'non-classical' HER2 FISH groups using the 2018 ASCO/CAP HER2 testing guideline [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-10-12.

Abstract P5-11-06: Does hormone expression by IHC predict ER pathway activity? An analysis in a metastatic breast cancer patient cohort

Background: Immunohistochemistry (IHC) staining for ER and progesterone (PR) receptors in breast cancer tissue is the current standard for testing for eligibility for hormone targeted therapies. However, these markers are imperfect predictors of response, and ER/PR expression can be heterogeneous, especially in the metastatic setting. Within an adjuvant tamoxifen-treated ER positive patient group functional ER pathway activity was associated with improved patient outcome (Verhaegh et al, Cancer Research 2014). This study investigated how ER/PR staining correlates with ER pathway activity in a cohort of metastatic breast cancers.

Methods: Cases of metastatic breast cancer with variable reported ER expression by IHC were selected from the Stanford Pathology Database. Cases were scored by a breast pathologist for percent cellularity of sample, percent and intensity of ER and PR staining, and a qualitative rating of heterogeneity of staining. Digital slides were annotated for areas of cellularity to perform ER pathway activity analysis. Functional ER pathway activitywas measured in a quantitative manner using a biologically validated method, based on Bayesian computational model inference of functional pathway activity from RT-qPCR measurements of mRNA levels of target genes of the pathway transcription factor, providing an ER Pathway Activity Score (PAS)(Verhaegh et al, Cancer Research 2014).

Results: A total of 64 samples were tested for ER/PR expression as well as for ER pathway analysis. Annotated tumor areas of 57 samples were used for measurement of ER PAS. 61.4% were ER expression high (defined as >50% ER IHC positive, mean 94.0%) and 38.6 % were ER low (defined as <50% ER IHC positive, mean 23.0%). ER high cases had higher mean ER PAS when compared to ER low cases (ER high, mean PAS 47.6, SD 19.2; versus ER low, mean PAS 19.4, SD 11.7; unpaired one-tailed 2-sample t-test p<0.001). Importantly, there was wide variation in ER PAS even in cases with high ER expression levels. PR levels did not correlate with ER PAS. Three cases had clustered areas with different ER expression levels within the tissue slide (heterogeneous cases), resulting in 7 separately analyzed areas; ER pathway activity was separately analyzed in these areas. ER PAS was remarkably similar across areas with variable ER staining, e.g. within one tissue slide, areas with 20% and 90% ER expression had nearly the same ER PAS.

Discussion: Grouping cases into high vs low ER IHC staining reveals expected differences in ER PAS. However, nuclear ER expression (IHC) levels may be an imperfect predictor of actual ER pathway activity on an individual case basis. Preliminary results on cases with regional heterogeneity for levels of ER IHC expression suggest that ER PAS is more homogenous than IHC levels. Clinical studies examining value of ER PAS to predict response to hormonal therapies are ongoing.

Citation Format: Yang S-R, van de Stolpe A, van Brussel A, van Ooijen H, Galimzianova A, Cohn DM, Beca F, Rubin DL, Allison KH. Does hormone expression by IHC predict ER pathway activity? An analysis in a metastatic breast cancer patient cohort [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-11-06.

Abstract P2-07-07: Development of a machine learning-based classifier for Oncotype DX® category prediction in a population of lymph node positive breast carcinoma patients

INTRODUCTION: Oncotype DX® (ODX) Assay is a valuable prognostic and predictive tool in ER+, Her2- invasive breast cancer (IBC). Initially tested and validated in lymph node (LN) negative patients, the indications of this test have been expanded to include patients with limited LN-positive disease. Several prediction systems have been developed to predict the ODX Recurrence Score (RS) with substantial performance in predicting a high vs low RS score but with low performance when predicting the 3 classes that compose the standard ODX. Additionally, many of these prediction systems have not been developed and/or tested for a population of LN+ patients.

OBJECTIVES: The primary objective of this study was to evaluate the performance of several previously published ODX RS predictive systems in a population of LN+ patients. Furthermore, we developed a machine-learning based classification system to accurately predict the ODX 3 category RS for this specific population.

METHODS: We conducted a retrospective search of Stanford's pathology database for all patients with LN+ IBC diagnosed between January 2013 and December 2017 with an ODX RS available. A total of 119 patients were identified for inclusion in this cohort. Our multivariate pathologic feature-based discriminatory model aimed to classify each case as belonging to the low, intermediate or high ODX RS category. We performed model validation by the 10-fold cross validation (10F-CV) method. The model's performance was assessed by comparing simple accuracy, balanced accuracy, F1 score (harmonic average of the precision and recall) and several concordance classification metrics.

RESULTS: Of the evaluated methods, Magee equations performed well in this population of LN+ patients with the modified Magee equation 2 displaying the best accuracy (70.9%) which was surprisingly better than originally reported (55.8%, in Klein et al. Mod Path. 2013). After an initial screen of methods and tuning of the best performing model, our model achieved an overall accuracy of 78.1% on 10F-CV with a 79.1 % balanced accuracy and no two-step discordances. This corresponded to an increase of weighted Cohen's kappa of 30% versus the best performing Magee equation in this cohort and an increase of 103% versus the modified Magee 1 equation (which uses the same features as our model except for tumor grade).

DISCUSSION: Classifiers aimed at providing an alternative to Oncotype DX testing are available and perform consistently across datasets. We are currently validating our approach in a population of 1000 LN-negative patients from the MSKCC and the SEER database. Due to the substantial performance of our machine learning-based classifier based on standard reported pathologic features, our model may be considered an alternative to the ODX standard testing or a screening method for ODX testing, especially for cases with where the cost and availability of the ODX test are a concern.

Citation Format: Beca F, Yang S-R, Gruber JG, Barry-Holson K, West R, Wen HY, Allison KH. Development of a machine learning-based classifier for Oncotype DX® category prediction in a population of lymph node positive breast carcinoma patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-07-07.

High-quality thulium iron garnet films with tunable perpendicular magnetic anisotropy by off-axis sputtering - correlation between magnetic properties and film strain

Thulium iron garnet (TmIG) films with perpendicular magnetic anisotropy (PMA) were grown on gadolinium gallium garnet (GGG) (111) substrates by off-axis sputtering. High-resolution synchrotron radiation X-ray diffraction studies and spherical aberration-corrected scanning transmission electron microscope (Cs-corrected STEM) images showed the excellent crystallinity of the films and their sharp interface with GGG. Damping constant of TmIG thin film was determined to be 0.0133 by frequency-dependent ferromagnetic resonance (FMR) measurements. The saturation magnetization (Ms) and the coercive field (Hc) were obtained systematically as a function of the longitudinal distance (L) between the sputtering target and the substrate. A 170% enhancement of PMA field (H⊥) was achieved by tuning the film composition to increase the tensile strain. Moreover, current-induced magnetization switching on a Pt/TmIG structure was demonstrated with an ultra-low critical current density (jc) of 2.5 × 106 A/cm2, an order of magnitude smaller than the previously reported value. We were able to tune Ms, Hc and H⊥ to obtain an ultra-low jc of switching the magnetization, showing the great potential of sputtered TmIG films for spintronics.

[Molecular typing characterization of food-borne methicillin-resistant Staphylococcus aureus in China]

Objective: To analyses the antimicrobial resistance and molecular characterization of 21 MRSA isolates cultured from retail foods from different provinces in China, and evaluate the molecular typing methods. Methods: Twenty-one MRSA isolates were obtained from national foodborne pathogen surveillance network in 2012 (Chinese salad, n=3; milk, n=1; cake, n=2; rice, n=1; cold noodle, n=1; spiced beef, n=1; dumpling, n=1; packed meal, n=1; salad, n=1; raw pork, n=9). The antimicrobial resistance of 21 strains to 12 antimicrobial agents was tested by broth dilution method. Polymerase chain reaction (PCR) and DNA sequencing were performed to obtain the genetic types of MLST (ST) and spa typing. The clonal complex (CC) was assigned by eBURST soft and the MLVA type (MT) and MLVA complex (MC) were identified via the database of the MLVA website (http://www.mlva.net). SmaI pulsed-field gel electrophoresis (SmaⅠ-PFGE) was also carried out to obtain the PFGE patterns of 21 strains. The genetic diversity and discriminatory power of typing were calculated by the Simpson's index of diversity (diversity index, DI) to find out the best genotyping method for MRSA. Results: All MRSA isolates showed multi-drug resistance(MDR), and were resistant to oxacillin, benzylpenicillin, clindamycin and erythromycin, and 71.4% (15/21), 47.6% (10/21), 42.9% (9/21) and 28.6% (6/21) of the MRSA isolates were resistant to tetracycline, ciprofloxacin, trimethoprim/sulfamethoxazole and gentamicin, respectively. Moreover, one strain was found to be resistant to all three antimicrobials of levofloxacin, moxifloxacin and rifampicin. Great diversity was found in these food-associated MRSA (6 STs, 7 spa types, and 9 MTs). PFGE patterns were more diverse than those of other three molecular typing methods (19 pulse types). The index of diversity (DI) of PFGE, MLVA, spa typing and MLST was 0.99, 0.80, 0.73, and 0.61, respectively. Among the MRSA isolates, CC9-ST9-t899-MT929-MC2236 (PFGE Cluster Ⅴ) was the most prevalent clone, which were all cultured from raw pork (9 isolates). Besides, two MRSA were identified as CC59-ST338-t437-MT621-MC621 (PFGE Cluster Ⅳ). Different clone had their own resistance spectrum profiles. Conclusion: The food-borne MRSA isolates were all MDR in this study. Different clones had their own resistance spectrum profiles. MLVA represented a promising tool for molecular epidemiology tracing of MRSA in foodborne disease events.

Strongly exchange-coupled and surface-state-modulated magnetization dynamics in Bi2Se3/yttrium iron garnet heterostructures

Harnessing the spin–momentum locking of topological surface states in conjunction with magnetic materials is the first step to realize novel topological insulator-based devices. Here, we report strong interfacial coupling in Bi₂Se₃/yttrium iron garnet (YIG) bilayers manifested as large interfacial in-plane magnetic anisotropy (IMA) and enhancement of damping probed by ferromagnetic resonance. The interfacial IMA and damping enhancement reaches a maximum when the Bi₂Se₃ film approaches its two-dimensional limit, indicating that topological surface states play an important role in the magnetization dynamics of YIG. Temperature-dependent ferromagnetic resonance of Bi₂Se₃/YIG reveals signatures of the magnetic proximity effect of T_C as high as 180 K, an emerging low-temperature perpendicular magnetic anisotropy competing the high-temperature IMA, and an increasing exchange effective field of YIG steadily increasing toward low temperature. Our study sheds light on the effects of topological insulators on magnetization dynamics, essential for the development of topological insulator-based spintronic devices.

Understanding the effects of topological insulators on magnetization dynamics of adjacent magnetic materials is essential for novel spintronic devices. Here, Fanchiang et al. report thickness dependence of interfacial in-plane magnetic anisotropy and damping enhancement in Bi₂Se₃/yttrium iron garnet (YIG) bilayers, indicating an important role of topological surface states in the magnetization dynamics of YIG.

Influence of pre-diagnostic cigarette smoking on colorectal cancer survival: overall and by tumour molecular phenotype

BACKGROUND

Smoking is a risk factor for incident colorectal cancer (CRC); however, it is unclear about its influence on survival after CRC diagnosis.

METHODS

A cohort of 706 CRC patients diagnosed from 1999 to 2003 in Newfoundland and Labrador, Canada, was followed for mortality and recurrence until April 2010. Smoking and other relevant data were collected by questionnaire after cancer diagnosis, using a referent period of '2 years before diagnosis' to capture pre-diagnosis information. Molecular analyses of microsatellite instability (MSI) status and BRAF V600E mutation status were performed in tumour tissue using standard techniques. Multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated with Cox proportional hazards regression, controlling for major prognostic factors.

RESULTS

Compared with never smokers, all-cause mortality (overall survival, OS) was higher for current (HR: 1.78; 95% CI: 1.04-3.06), but not for former (HR: 1.06; 95% CI: 0.71-1.59) smokers. The associations of cigarette smoking with the study outcomes were higher among patients with ≥40 pack-years of smoking (OS: HR: 1.72; 95% CI: 1.03-2.85; disease-free survival (DFS: HR: 1.99; 95% CI: 1.25-3.19), those who smoked ≥30 cigarettes per day (DFS: HR: 1.80; 95% CI: 1.22-2.67), and those with microsatellite stable (MSS) or MSI-low tumours (OS: HR: 1.38; 95% CI: 1.04-1.82 and DFS: HR: 1.32; 95% CI: 1.01-1.72). Potential heterogeneity was noted for sex (DFS HR: 1.68 for men and 1.01 for women: P for heterogeneity=0.04), and age at diagnosis (OS: HR: 1.11 for patients aged <60 and 1.69 for patients aged ≥60: P for heterogeneity=0.03).

CONCLUSIONS

Pre-diagnosis cigarette smoking is associated with worsened prognosis among patients with CRC.

A bio-inspired two-layer multiple-walled carbon nanotube-polymer composite sensor array and a bio-inspired fast-adaptive readout circuit for a portable electronic nose

We report a fully integrated, portable, battery-operated electronic nose system comprising a bio-inspired two-layer multiple-walled carbon nanotube (MWNT)-polymer composite sensor array, a bio-inspired fast-adaptive readout circuit, and a microprocessor embedded with a pattern recognition algorithm. The two-layer MWNT-polymer composite sensor is simple to operate, and the membrane quality can be easily controlled. These two-layer membranes have improved sensitivity and stability. The fast-adaptive readout circuit responds to the sensor response, while tuning out the long-term constant background humidity, temperature, and odors. This portable electronic nose system successfully classified four complex alcohol samples 40 times for each sample; these samples were sake, sorghum liquor, medical liquor, and whisky.

Properties of BK(Ca) channels in oral keratinocytes

Keratinocytes are important for epithelial antimicrobial barrier function. The activity of ion channels can affect the proliferation of keratinocytes. Little is known about Ca2+-activated K+ currents in these cells. Ion currents in normal human oral keratinocytes were characterized with a patch-clamp technique. In whole-cell configuration, depolarizing pulses evoked K+ outward currents (I(K)) in oral keratinocytes. Iberiotoxin (200 nM) and paxilline (1 microM) suppressed I(K); however, neither apamin (200 nM) nor 5-hydroxydecanoate (30 microM) had any effects on it. Caffeic acid phenethyl ester, a compound of honeybee propolis, increased I(K) with an EC50 value of 12.8 +/- 1.2 microM. In inside-out patches, a BK(Ca) channel was observed in keratinocytes, but not in oral squamous carcinoma (OCE-M1) cells. Caffeic acid phenethyl ester or cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate applied to the intracellular surface of a detached patch increased BK(Ca)-channel activity. The results demonstrate that the properties of BK(Ca) channels in normal human oral keratinocytes are similar to those described in other types of cells. Caffeic acid derivatives can also stimulate BK(Ca)-channel activity directly.

[CT diagnosis of maxillary mucoceles]

CT signs of thirty-six cases of maxillary mucocele surgically and pathologically proved were analyzed. 20 of 36 cases revealed as low density lesion. 16 of 36 cases revealed as isodensity or high density lesion. They were morphologically classified as three types: nodular type, inflammatory type, bony defect type. Cystic morphology and fluid density within the lesion obviously indicated mucocele. Differential diagnosis should be made between mucocele and polyps, when the lesion revealed as soft tissue density. Inflammatory type need to be distinguished from maxillary inflammation. And bony defect type should be distinguished from the benign or malignant tumor of maxillary sinus. The islet sign and bone sclerosis are considered to be valuable for the differential diagnosis.

Anti-inflammatory and hepatoprotective effects of Solanum alatum

Solanum alatum aqueous extract was investigated on carrageenin-induced edema and on CCl4-induced liver injury. The extract (100 or 200 mg/kg body weight) exhibited both anti-inflammatory and hepatoprotective activities. The effects were more prominent at the dose of 200 mg/kg. Histological changes such as necrosis, fatty changes, ballooning degeneration, and inflammatory infiltration of lymphocytes and Kupffer cells around the central veins were concurrently improved by treatment with the S. alatum aqueous extract.

The effects of glutamate and GABA (gamma-amino-butyric-acid) on spontaneous acetylcholine release at the neuromuscular junction in Xenopus laevis embryo cell cultures

The miniature endplate currents (MEPC's) were recorded at the neuromuscular junction of Xenopus laevis embryo neuron-muscle co-cultured cells. These MEPC's were due to the spontaneous release of acetylcholine from the nerve terminal. After perfusion with glutamate (10 mumol/L), both frequency and amplitude of the MEPC's increased. After washing away of glutamate, this effect persisted. We named this phenomena "Long-Term Facilitation". GABA (20 mumol/L) on the other hand had an inhibitory effect on both frequency and amplitude of the MEPC's. After washing away of GABA, the MEPC frequency and amplitude increased. We named this effect "Post-Potentiation". Local perfusion experiments furthermore indicated that the effect of glutamate was restricted to the neuromuscular junction, the effect of GABA was restricted to the soma.

[Two types of nondepolarizing-activated calcium channels on the spinal cholinergic neurons from embryonic Xenopus laevis]

Single calcium channel current was studied on the identified spinal cholinergic neurons from embryonic Xenopus laevis with patch clamp method. The results indicate that some calcium channels show opening activity at resting membrane potential. According to the characteristics of conductance and kinetics of such channels, they could be divided into two types: a stretch sensitive Type-NS with a slope conductance of 7.5 pS (mean open time 0.58 ms at resting membrane potential) and a Type-NL with a slope conductance of 16.7 pS (and two opening times of 2 ms and 19.3 ms). Both types of channel are predominantly active at resting potential and negative membrane phases. It is suggested that they may be involved in the calcium-dependent neuronal events at resting state.

[Mechanisms of effects of electrical stimulation of "Renzhong" (Du 26) on phrenic discharge in rabbits]

Experiments were performed on urethane anesthetized, bivagotomized, flaxedil paralyzed and artificially ventilated rabbits. The effects of stimulation of "Renzhong" (Du 26) on phrenic discharge were not caused secondarily by blood pressure alteration. The effects were abolished by bilateral section of infraorbital nerves, were similar to those of stimulation of the central end of the infraorbital nerve, and were not qualitatively changed by mid-colliculi decerebration. The responses of the bulbar respiratory related neurons were coordinated with those of the phrenic nerve to stimulation of "Renzhong", i.e., the responses of almost all of the inspiratory neurons were consistent with phrenic responses and those of the most of the expiratory neurons were contrary to them. It can be concluded that the effects of electrical stimulation of "Renzhong" on phrenic discharge result from the nervous reflex. Its afferent is infraorbital nerve and the higher centers are not essential for it. The bulbar respiratory related neurons might play an important part in it.

Cloning and sequencing of a beta-thalassemia gene from south China

A beta-thalassemia gene from a patient with beta+-thalassemia in South China was cloned and sequenced. A four nucleotide (TCTT) deletion in codons 41 and 42 was found. This is the most common beta-thalassemia gene in South China and the first mutant identified on China mainland.