Ischaemia induced alternans of action potential duration in the intact-heart: dependence on coronary flow, preload and cycle length

Clinical and experimental evidence relate action potential duration(APD) alternans to ischaemic heart disease and ventricular arrhythmias.The present investigation was performed to study the quantitativerelationship between APD alternans and the degree ofischaemia,loading conditions and cycle length (CL) in an intact heart. Monophasic action potentials (MAP) were simultaneously recordedby contact electrodes from two left (LV) undone right ventricular(RV) sites in 20 Langendorff-perfused rabbit hearts. The preparationswere subjected to global ischaemia at flow rates ranging from40% of normal flow to complete cessation of flow. Pacing wasperformed at either constant or regularly changing CL. The magnitudeof APD alternans was expressed as beat-to-beat differences inaction potential duration of two consecutive MAPs. During normalper fusion, neither very fast pacing at a CL of 200 ms nor periodicalrate switches resulted in persistent APD alternans. Pacing ata constant CL of 800 ms did not induce A PD alternans at completecessation of flow for 6 min. However, alternans developed progressivelyat a constant CL of 400 ms after 2.8±0.3 min of completeischaemia at the pre-loaded LV, andafter 4.6±0.4 minat the unloaded RV (P<0.01). The reduction of preload atthe LV from 15 to 5 mmftg end-diastolic pressure delayed developmentof APD alternans from 2.8±0.3 min to 4.3±0.4 min(P < 0.05) at 400 ms CL. Following graded under per fusionof 40%, 20% and 10% of initial flow, persistent APD alternansdeveloped in relation to the degree of flow reduction and increasedprogressively with duration ofischaemia. APD alternans at theLV always preceded the onset of APD alternans at the RV. Inexperiments with identical flow rates the shortest CL of 200ms resulted in the greatest and earliest initiation of APD alternanscompared to the longer CL (P<0.01, P<0.001). An increasein CL from 400 to 800 ms immediately abolished APD alternans,generated by the shorter CL, at any time during the 6 min periodof complete ischaemia. Similarly, increasing the cycle lengthfrom 200 or 400 to 600 ms eliminated APD alternans up to 6 minof ischaemia and significantly reduced its magnitude between7 and 10 min within a few beats. We conclude that persistent APD alternans is a characteristicfinding in the rabbit heart during global ischaemia. It is asensitive parameter of the severity of ischaemia and dependson the degree and duration of ischaemia as well as on the preload.The CL appears to have an independent effect on the generationof APD alternans, which is functionally separate from the effectof CL on the ischaemic burden. An eventual impact of these observationscould be the application of APD alternans as a diagnostic toolin electrophysiological examinations of myocardial ischaemiain experimental and clinical settings.     

Dogger bank itch. 4. An eczema-causing sulfoxonium ion from the marine animal, Alcyonidium gelatinosum [Bryozoa]

Repeated exposure to the marine bryozoan, Alcyonidium gelatinosum, frequently provokes an eczematous allergic contact dermatitis known as the "Dogger Bank Itch". The dermatitis, representing a severe occupational disease, is especially widely distributed among trawlermen working in the Dogger Bank area in the North Sea. The allergy is shown to belong to the type of cell-mediated hypersensitivity. The hapten has been identified as the (2-hydroxyethyl)dimethylsulfoxonium ion. The isolation, structure determination and synthesis are discussed.     

YAG激光与药物结合治疗文唇后接触性唇炎130例临床观察

目的探讨YAG激光与药物联合治疗文唇后接触性唇炎的疗效。方法随机选取130例文唇后接触性唇炎患者，应用美国Coherent公司生产的多功能多波长皮肤美容激光器（Nd：YAG激光）进行治疗，联合应用抗组胺药物等内服以及皮质类固醇激素外用。结果130例患者，完全治愈112例（占86．2％），显效16例（占12．3％），有效2例（占1．5％），无效为0，总有效率100％。结论YAG激光与药物结合治疗文唇后接触性唇炎获得满意疗效，具有创伤小，疗效高，副作用少，不留疤痕等特点。     

角膜屈光性手术后的屈光矫正

目的：探讨角膜屈光性手术后视力低下的原因及屈光矫正方法。方法：对施行RK、PRK、LASIK术后来我中心寻求进一步视力矫正的48例86只眼，经裂隙灯、电脑验光、角膜曲率仪、计算机辅助的角膜地形图、对比敏感度检查，以及主、客观验光，分析其视力下降、矫正不良的原因，并探讨选择框架眼镜、各种设计的软性接触镜(SCL)和透气性硬性接触镜(RGPCL)，以及角膜矫形镜(Ortho-K CL)等进行屈光再矫正的效果和特点。结果：28只眼并发圆锥角膜，95．8％视力≤0．1，全部利用不同设计的RGPCL矫正，70．8％矫正视力≥0．8。16只眼为高度近视、高度散光，86．2％视力≤0．1，利用RGPCL，SCL和Ortho-K CL矫正，76．5％矫正视力≥0．8。34只近视、散光眼和5只远视、散光眼，60．0％～61．8％视力低于0．4，利用框架眼镜和各类接触镜矫正，80．0％以上获得良好矫正视力。另有3只眼RK术后因遭撞击致角膜裂伤后形成角膜白斑，均选用加虹膜色彩的接触镜矫正。结论：RK、PRK、LASIK术后视力低下的主要原因是医源性圆锥角膜和高度近视、高度散光。积极选择验配各类适宜的接触镜可显著提高视力，RGPCL最为有效。     

软性角膜接触镜诱发角膜改变的共焦显微镜观察

目的应用共焦显微镜对长期配戴软性角膜接触镜所诱发的活体角膜组织改变情况进行观察.方法选择2002年8月～2003年4月于天津医科大学眼科中心门诊进行检查的患者36例(72眼),其中男性19例(36眼),女性17例(34眼),平均年龄为(27.63±10.7)岁,平均等效球镜度为(-5.87±0.67)D(-1.0～-9.0D),平均日戴时间超过8h,平均戴镜时间为(5.60±3.38)年(1～13年).选择未戴角膜接触镜者41例(82眼)作为对照组,其中男性20例(40眼),女性21例(42眼).平均年龄为(28.54±12.4)岁(18～52岁),平均等效球镜度为(-5.94±4.06)D(-1.25～-13D).结果戴软性角膜接触镜组角膜上皮的厚度为(42.6±6.1)μm,前基质角膜细胞密度为(1243±116)个/μm2,与对照组比较存在差异,其差异有显著性.戴角膜接触镜组的内皮细胞密度与对照组之间无差异,多形性内皮细胞和内皮细胞异形性百分比与对照组之间存在差异,其差异有显著性.结论长期戴软性角膜接触镜可诱发角膜组织改变.     

Non-compliance with lens care and maintenance in diabetic contact lens wearers

We hypothesize that diabetic contact lens wearers may represent a special group displaying higher levels of compliance with their lens care regimens as a result of learned behaviour relating to maintenance of their diabetic condition. To test this hypothesis, a prospective, single centre, controlled, masked study was performed whereby 29 diabetic contact lens patients and 29 non-diabetic control subjects were issued with disposable hydrogel contact lenses and a multipurpose lens care regimen. All participants were given identical instruction on lens care and maintenance. Compliance levels were assessed at a 12-month aftercare appointment by demonstration and questionnaire. Twenty-four different aspects of compliance were scored, 12 by observation and 12 by questionnaire report, of which only two showed a significant difference between the diabetic and control groups. Although the combined population of contact lens wearers was generally compliant, there were examples of non-compliance in both groups. Neither the duration of diabetes nor the degree of metabolic control appeared to have a significant effect on compliance. The results suggest that eye care practitioners cannot assume that diabetic patients will be more compliant with contact lens care and maintenance than non-diabetic patients.     

Aryl hydrocarbon receptor-activating polychlorinated biphenyls and their hydroxylated metabolites induce cell proliferation in contact-inhibited rat liver epithelial cells.

Polychlorinated biphenyls (PCBs) exhibit tumor-promoting effects in experimental animals. We investigated effects of six model PCB congeners and hydroxylated PCB metabolites on proliferation of contact-inhibited rat liver epithelial WB-F344 cells. The 'dioxin-like' PCB congeners, PCB 126, PCB 105, and 4'-OH-PCB 79, a metabolite of the planar PCB 77 congener, induced cell proliferation in a concentration-dependent manner. In contrast, the 'non-dioxin-like' compounds that are not aryl hydrocarbon receptor (AhR) agonists, PCB 47, PCB 153, and 4-OH-PCB 187, an abundant noncoplanar PCB metabolite, had no effect on cell proliferation at concentrations up to 10 muM. The concentrations of dioxin-like PCBs leading to cell proliferation corresponded with the levels inducing the expression of cytochrome P450 1A1 mRNA, suggesting that the release from contact inhibition was associated with AhR activation. The effects of PCB 126 and PCB 153 on expression of proteins controlling G0/G1-S-phase transition and S-phase progression were compared. Only PCB 126 was found to upregulate cyclin A and D2 protein levels, and to increase both total cyclin-dependent kinase 2 (cdk2) and cyclin A/cdk2 complex activities. Despite the observed upregulation of cyclin D2, no increase in cdk4 activity was observed. The expression of cdk inhibitor p27Kip1 was not affected by either PCB 126 or PCB 153. These results suggest that dioxin-like PCBs can induce cell proliferation of contact-inhibited rat liver epithelial cells by increasing cyclin A protein levels, a process that then leads to upregulation of cyclin A/cdk2 activity and initiation of DNA replication. This mechanism could be involved in tumor-promoting effects of dioxin-like PCBs.     

稳定型圆锥角膜患者植入新型Phakic角膜接触镜的视觉效果分析

目的：评估可植入式Phakic角膜接触镜治疗稳定型圆锥角膜患者的疗效、安全性、稳定性和可预测性。

方法：共14例患者采用植入式Phakic角膜接触镜(IPCL)矫正屈光不正,测量了未矫正视力、最佳矫正视力、离焦曲线、对比敏感度、屈光度及可能的副作用。评估结果超过6mo。

结果：平均等效球镜度(SE)和散光在术后6mo末次检查时由术前-6.94±2.79 DS和-4.24±1.42 DC分别变为术后-0.23±0.43 DS和-1.05±0.49 DC。术前平均Snellen视力为0.18±0.10。6mo内未矫正视力和最佳矫正视力平均值分别为0.13±0.10和0.05±0.15。平均安全指数为1.11。所有眼视力均无降低,其中22眼视力提高超过1行。20眼(71.4%)屈光度在0.50 D以内,27眼(96.42%)在±1.00 D以内。术后1wk至6mo,屈光度变化为-0.23±0.43(范围： -1.00至+0.75)。6mo内角膜内皮细胞(ECL)丢失率小于5%。术后6mo眼压(IOP)为11.32±2.28 mmHg。

结论：Toric植入式Phakic角膜接触镜在矫正与稳定圆锥角膜相关的近视和近视散光方面具有有效性、安全性和可预测性。     

美容相关眼部损伤急性期的临床表现

目的：探讨美容相关眼部损伤急性期的临床表现。

方法： 回顾性研究。收集2016-04/2021-10因美容导致的眼部损伤患者53例89眼,分析患者急性期的临床特征,包括性别、年龄、受伤眼别、临床表现、致伤原因、治疗过程及预后。

结果：纳入53例89眼患者均为女性,年龄22-45(平均28.4±6.7)岁。单眼损伤17例,双眼损伤36例。2种或2种以上眼部损伤可累及同一眼。导致眼部损伤的主要美容操作包括：纹眼线38眼(43%); 嫁接睫毛18眼(20%); 去除假睫毛11眼(12%); 涂睫毛膏8眼(9%); 双重睑手术6眼(7%); 其他8眼(9%)。主要眼部损伤类型包括：角膜损伤56眼(63%); 眼睑接触性皮炎26眼(29%); 结膜炎19眼(21%); 眼睑反应性水肿13眼(15%); 眼表异物12眼(14%); 睑缘细菌性感染10眼(11%); 其他5眼(6%),这其中包括因眼周注射玻尿酸导致视网膜中央动脉阻塞1眼(1%)。74眼经过正规治疗可在1-2 wk内痊愈,3眼出现丝状角膜炎,视网膜中央动脉阻塞1眼预后差。

结论：美容相关眼部损伤见于中青年女性,引发眼部损伤最常见的美容操作是纹眼线,最主要损伤类型为角膜损伤。美容相关眼部损伤多数可以预防,治疗方法有效且总体预后良好。     

The Role of the Graphene Oxide (GO) and Reduced Graphene Oxide (RGO) Intermediate Layer in CZTSSe Thin-Film Solar Cells

Cu₂ZnSn(S,Se)₄ (CZTSSe) solar cells with low cost and eco-friendly characteristics are attractive as future sources of electricity generation, but low conversion efficiency remains an issue. To improve conversion efficiency, a method of inserting intermediate layers between the CZTSSe absorber film and the Mo back contact is used to suppress the formation of MoSe₂ and decomposition of CZTSSe. Among the candidates for the intermediate layer, graphene oxide (GO) and reduced GO have excellent properties, including high-charge mobility and low processing cost. Depending on the type of GO, the solar cell parameters, such as fill factor (FF), were enhanced. Thus, the conversion efficiency of 6.3% was achieved using the chemically reduced GO intermediate layer with significantly improved FF.