Semantic retrieval of spoken words with an obliterated initial phoneme in a sentence context

Perception of a phoneme may occur even when the speech sound is missing (e.g., when an extraneous noise replaces the sound). This phenomenon, called phonemic restoration, has been observed to depend on the type of distortion. It requires a replacing sound that provides acoustic input to the auditory system, since the restoration has not been found when a speech sound was replaced by silence. We examined the brain activation underlying speech processing when the word's initial phoneme was completely replaced by a silent gap. Event-related potentials (ERPs) and reaction times (RTs) were measured as indicators of semantic processing of sentence final words. Slower voice onset times during repetition of the manipulated words as compared to normal words indicated increased difficulty in retrieving their meaning. The N400, which is related to the increased demands of the semantic integration of words, was elicited by less expected words as compared to highly expected ones. For manipulated words, the N400 was elicited at the same latency than for normal words, with respect to the onset of the remaining word fragment. The amplitude of the N400 was not increased, nor did it last longer, thereby indicating successful retrieval of the word's meaning based on the semantic context and remaining phonetic information. Thus, semantic retrieval does not seem to require the word's initial phoneme to be present in a sentence context. The results suggest that both context-driven expectancy (top–down) and stimulus-driven processes (bottom–up) are utilized in word processing and contribute to the overall N400 response.     

Role of connexin 32 in acetaminophen toxicity in a knockout mice model

Gap junctional intercellular communication (GJIC), by which glutathione (GSH) and inorganic ions are transmitted to neighboring cells, is recognized as being largely involved in toxic processes of chemicals. We examined acetaminophen (APAP)-induced hepatotoxicity clinicopathologically using male wild-type mice and mice lacking the gene for connexin32, a major gap junction protein in the liver [knockout (Cx32KO) mice]. When APAP was intraperitoneally administered at doses of 100, 200, or 300 mg/kg, hepatic centrilobular necrosis with elevated plasma aminotransferase activities was observed in wild-type mice receiving 300 mg/kg, and in Cx32KO mice given 100 mg/kg or more. At 200 mg/kg or more, hepatic GSH and GSSG contents decreased significantly and the effect was more severe in wild-type mice than in Cx32KO mice. On the other hand, markedly decreased GSH staining was observed in the hepatic centrilobular zones of Cx32KO mice compared to that of wild-type mice. These results demonstrate that Cx32KO mice are more susceptible to APAP hepatotoxicity than wild-type mice, and indicate that the distribution of GSH of the centrilobular zones in the hepatic lobules, rather than GSH and GSSG contents in the liver, is important in APAP hepatotoxicity. In conclusion, Cx32 protects against APAP-induced hepatic centrilobular necrosis in mice, which may be through the GSH transmission to neighboring hepatocytes by GJIC.     

星形胶质在癫(癎)中的生物学机制研究进展

离子通道改变、神经递质及其受体调控异常、血脑屏障损伤、炎症、氧化应激损伤等均与癫(癎)发作有关.近年来通过对癫(癎)动物模型、癫(癎)患者尸体解剖或手术切除患者癫(癎)病灶的研究表明,星形胶质与癫(癎)的发生发展有一定的关系,但两者之间的因果关系一直没有定论.目前多数抗癫(癎)药物都是针对神经元,对患者的认知和脑功能都有一定的影响.因此,从星形胶质的角度去探讨癫(癎)的发病机制,有助于发现新的干预靶点以开发新型抗癫(癎)药物.     

The metabolic inhibitor antimycin A can disrupt cell-to-cell communication by an ATP- and Ca2+-independent mechanism

In cardiac myocytes of new-born rats, the degree of intercellular communication through gap junctional channels closely depends on the metabolic state of the cells. In contrast, in stably transfected HeLa cells expressing rat cardiac connexin43 (Cx43, the main channel-forming protein present in ventricular myocytes), a major part of junctional communication persisted in ATP-depleted conditions, in the presence of a metabolic inhibitor (KCN) or of a broad spectrum inhibitor of protein kinases (H7). However, another metabolic inhibitor, antimycin A, which like cyanide inhibits electron transfer in the respiratory chain, totally interrupted cell-to-cell communication between Cx43-HeLa cells, even in whole-cell conditions, when ATP (5 mM) was present. Antimycin A caused a modest increase in cytosolic calcium concentration; however, junctional uncoupling still occurred when this rise was prevented. Conditions of ischemic insult (e.g. ischemia or chemical hypoxia) frequently cause the activation of protein kinases, particularly of Src and MAP kinases, and such activations are known to markedly disrupt gap junctional communication. Antimycin-induced junctional uncoupling occurred even in the presence of inhibitors of these kinases. Antimycin A appears able to cause junctional uncoupling either through the ATP depletion it induces as a metabolic poison or via a direct action on gap junction constituents.     

Connexin 36 Mediates Orofacial Pain Hypersensitivity Through GluK2 and TRPA1

Trigeminal neuralgia is a debilitating condition, and the pain easily spreads to other parts of the face. Here, we established a mouse model of partial transection of the infraorbital nerve (pT-ION) and found that the Connexin 36 (Cx36) inhibitor mefloquine caused greater alleviation of pT-ION-induced cold allodynia compared to the reduction of mechanical allodynia. Mefloquine reversed the pT-ION-induced upregulation of Cx36, glutamate receptor ionotropic kainate 2 (GluK2), transient receptor potential ankyrin 1 (TRPA1), and phosphorylated extracellular signal regulated kinase (p-ERK) in the trigeminal ganglion. Cold allodynia but not mechanical allodynia induced by pT-ION or by virus-mediated overexpression of Cx36 in the trigeminal ganglion was reversed by the GluK2 antagonist NS102, and knocking down Cx36 expression in Nav1.8-expressing nociceptors by injecting virus into the orofacial skin area of Nav1.8-Cre mice attenuated cold allodynia but not mechanical allodynia. In conclusion, we show that Cx36 contributes greatly to the development of orofacial pain hypersensitivity through GluK2, TRPA1, and p-ERK signaling.Electronic supplementary materialThe online version of this article (10.1007/s12264-020-00594-4) contains supplementary material, which is available to authorized users.     

Temperature dependence of gap junction properties in neonatal rat heart cells

Cell pairs of neonatal rat hearts were used to study the influence of temperature on the electrical properties of gap junctions. A dual voltage-clamp method was adopted, which allowed the voltage gradient between the cells to be controlled and the intercellular current flow to be measured. Cell pairs with normal coupling revealed a positive correlation between the conductance of the junctional membranes, g _j, and temperature. Cooling from 37° C to 14° C led to a steeper decrease in g _j, cooling from 14° C to -2° C to a shallower decrease (37° C: g _j=48.3 nS; 14° C: g _j=21.4 nS;-2°C: g _j=17.5 nS), corresponding to a temperature coefficient, Q ₁₀, of 1.43 and 1.14 respectively. The existence of two Q ₁₀ values implies that g _j may be controlled by enzymatic reactions. When g _j was low, i. e. below 5 nS (conditions: low temperature; treatment with 3 mM heptanol), it showed voltage-dependent gating. This property was not visible when g _j was large, i. e. 20–70 nS (conditions: high temperature; normal saline), presumably because of series resistances (pipette resistance). Cell pairs with weak intrinsic coupling and normally coupled cell pairs treated with 3 mM heptanol revealed a positive correlation between the conductance of single gap-junction channels, _j, and temperature (37° C: 75.6 pS; -2°C: 19.6 pS), corresponding to a Q ₁₀ of 1.41.     

Pannexin-1在癫痫大鼠皮层的表达

目的 观察缝隙连接蛋白pannexin-1在癫痫大鼠脑内的表达情况.方法 将健康雄性SD大鼠,随机分为正常对照组和癫痫组.采用腹腔注射戊四氮建立癫痫模型,大鼠点燃后的惊厥行为按照Racine标准进行观察评分,通过免疫组织化学和Western blot的方法,比较癫痫组和对照组皮层pannexin-1的表达差异.结果 免疫组织化学染色发现癫痫组大鼠皮层内表达pannexin-1的阳性细胞数明显增多为(36.24±6.64)个,对照组为(21.36±5.48)个,两组比较差异有统计学意义(P＜0.01);Western blot实验结果显示癫痫组大鼠皮层表达pannexin-1明显高于对照组,两者比较差异有统计学意义(P＜0.01).结论 癫痫发作将上调大鼠皮层内缝隙连接蛋白pannexin-1的表达,后者可能通过影响离子通道的开放以及神经递质的释放,参与癫痫异常放电的产生和扩布.     

芹黄素提高胸苷激酶基因系统治疗前列腺癌疗效的研究

目的　观察芹黄素 (apigenin)对前列腺癌 (PC)细胞PC 3m生长的影响及其对单纯疱疹胸苷激酶 /更昔洛韦 (HSV tk/GCV)系统“旁观者效应”的调控 ,寻求增强该系统对PCa疗效的途径。方法　四甲基偶氮唑盐比色法 (MTT法 )检测 1、10、10 0 μmol/Lapigenin对PC 3m细胞生长的影响 ,观察 10 μmol/Lapigenin预处理后GCV对tk基因阳性 (tk+ )比例为 10 %和 5 %的混合细胞的杀伤作用及 18 α 甘草次酸 ( 18 α glycyrrhetinicacidAGA)对其影响 ,并检测apigenin联合GCV的杀伤效应。结果　Apigenin可抑制PCa细胞增殖 ,呈时间和剂量依赖关系 (P <0 .0 5 0 ) ;低浓度( 10 μmol/L) apigenin预处理对PC 3m细胞增殖无影响但可使“旁观者效应”明显增强 (P <0 .0 0 1) ,10 μmol/L和 10 0 μmol/LGCV对tk+ 为 10 %细胞的杀伤率由 ( 16.15± 1.64 ) %和 ( 2 3 .46± 3 .2 1) %提高到 ( 4 5 .89± 3 .2 8) %和 ( 5 9.86± 2 .44 ) % ,该作用可被AGA抵消。联合应用apigenin和GCV后杀伤率更为显著 ,达 ( 62 .5 8± 4.2 9) %和 ( 83 .16± 3 .72 ) %。结论　Apigenin不仅可以直接杀伤PC细胞 ,还可通过增强HSV tk/GCV系统“旁观者效应” ,发挥间接杀瘤效应 ,从而提高该系统治疗PC疗效。     

Aberrant trafficking of a Leu89Pro connexin32 mutant associated with X-linked dominant Charcot–Marie–Tooth disease

Objective: To determine the functional abnormalities of the Leu89Pro mutation in connexin32 (CX32), which we have previously reported is present within an X-linked dominant Charcot–Marie–Tooth disease family. In this family, male patients were moderately to severely affected.

Methods: We performed immunofluorescence to investigate whether the Leu89Pro CX32 protein was transported to the cell membrane in HeLa and Schwann cells. First, we constructed the eukaryotic express plasmids expressing CX32 (wild-type or Leu89Pro) and enhanced green fluorescent protein by the gene recombination technology. Then the recombinant plasmids were transiently transfected into communication-incompetent HeLa cells and human Schwann cells by the lipofectamine method. Later, we double-labeled cells for both CX32 and markers of the ER (calnexin) or the Golgi (58-kDa protein) at 24 h or 48 h. The images were collected using a Leica TCS SP5 II confocal microscope.

Results: The mutant CX32 protein was localized in the endoplasmic reticulum and failed to reach the cell membrane to form gap junctions.

Conclusion: Our results indicated that the Leu89Pro substitution in the second transmembrane domain of CX32 disrupts the trafficking of the protein, inhibiting the assembly of CX32 gap junctions, which in turn may result in peripheral neuropathy. This functional abnormality may explain the moderate to severe phenotype seen in Leu89Pro patients, and as such represents a promising therapeutic target in the treatment of this subset of CMTX patients.     

Migration and Inducible Displacement of the Bicruciate-Stabilized Total Knee Arthroplasty: A Randomized Controlled Trial of Gap Balancing and Measured Resection Techniques

BackgroundThe goal of this study is to investigate the migration and inducible displacement of a bicruciate-stabilized (BCS) total knee arthroplasty implanted using gap balancing (GB) or measured resection (MR) surgical techniques. We hypothesized equal migration and displacement between the techniques.MethodsThe study is a single-blinded, prospective, randomized controlled trial, with allocation of 71 patients to either GB or MR groups. Fifteen patients were withdrawn, resulting in 31 patients in the GB group and 25 in the MR group. Patients received the JOURNEY II? BCS implant. Migration and inducible displacement were evaluated using radiostereometric analysis and patient examinations were performed at a 2-week baseline, and at 6 weeks, 3 months, 6 months, 1 year, and 2 years postoperation.ResultsNo differences (P > .05) existed between GB and MR groups for any measurement of tibial or femoral migration. Both groups had tibial migrations below 0.5 mm from baseline to 6 months, and below 0.2 mm from both 6 months to 1 year and 1-2 years postoperation. No differences (P > .05) were found between GB and MR groups for inducible displacement.ConclusionNo differences were found in implant migration or inducible displacement between GB and MR groups. The BCS implant can be expected to have migration risks on par with industry standards and both surgical techniques are safe and effective options for implantation of this implant design.