Diblock Copolymers Based on 1,4‐Dioxan‐2‐one and ε‐Caprolactone: Characterization and Thermal Properties

Summary: Various poly(ε‐caprolactone‐block‐1,4‐dioxan‐2‐one) (P(CL‐block‐PDX)) block copolymers were prepared according to the living/controlled ring‐opening polymerization (ROP) of 1,4‐dioxan‐2‐one (PDX) as initiated by in situ generated ω‐aluminium alkoxides poly(ε‐caprolactone) (PCL) chains in toluene at 25 °C. 1 ¹H NMR, PCS and TEM measurements have attested for the formation of colloids attributed to a growing PPDX core surrounded by a solvating PCL shell during the polymerization of PDX promoted by ω‐Al alkoxide PCL chains in toluene. The thermal behavior of the P(CL‐block‐PDX) copolymers was studied by DSC; showing two distinct melting temperatures (as well as two glass transition temperatures) similar to those of the respective homopolyesters. Finally, the thermal degradation of the P(CL‐block‐PDX) block copolymers was investigated by TGA simultaneously coupled to a FT‐IR spectrometer and a mass spectrometer for evolved gas analysis (EGA). The degradation occurred in two consecutive steps involving a first unzipping depolymerization of the PPDX blocks followed by the degradation of the PCL blocks via both ester pyrolysis and unzipping reactions.

TEM observation of P(CL‐block‐PDX) block copolyesters ( = 11 600 and = 22 100) as formed by vaporization starting from a diluted suspension in toluene/TCE mixture solvent (50/50 v/v).     

A Novel Macroinitiator for the Synthesis of Triblock Copolymers via Atom Transfer Radical Polymerization: Polystyrene‐block‐poly(bisphenol A carbonate)‐block‐polystyrene and Poly(methyl methacrylate)‐block‐poly(bisphenol A carbonate)‐block‐poly(methyl methacrylate)

Summary: Bis(hydroxy)telechelic bisphenol A polycarbonate (PC) was prepared via melt polycondensation of bisphenol A (BPA) and diphenyl carbonate (DPC) using lanthanum(III ) acetylacetonate as a catalyst for transesterification. Subsequently, the polycarbonate was converted to a bifunctional macroinitiator for atom transfer radical polymerization (ATRP) with the reagent, α‐chlorophenylacetyl chloride. The macroinitiator was used for the polymerization of styrene (S) and methyl methacrylate (MMA) to give PS‐block‐PC‐block‐PS and PMMA‐block‐PC‐block‐PMMA triblock copolymers. These block copolymers were characterized by NMR and GPC. When styrene and methyl methacrylate were used in large excess, significant shifts toward high molecular weights were observed with quantitative consumption of the macroinitiator. Several ligands were studied in combination with CuCl as the ATRP catalyst. Kinetic studies reveal the controlled nature of the polymerization reaction for all the ligands used.

Formation of a bifunctional ATRP macroinitiator by esterification of bis(hydroxy)telechelic PC with α‐chlorophenylacetyl chloride.     

Pathological Aspects of Radiofrequency Catheter Ablation of the Canine Atrioventricular Node and Bundle of His

Radiofrequency catheter ablation of the atrioventricular (AV) node or bundle of His was performed in 12 adult mongrel dogs. The aim was to create chronic incomplete AV block (first- and second-degree AV block) and to examine the histopathology of the ablated lesions. However, the late electrophysiological results (2 4 weeks follow up) were various: normal in 2 dogs, mild PR prolongation (< 50%) in 2 dogs, first-degree AV block (PR prolongation a 50%) in 2 dogs, second degree AV block in 2 dogs, complete AV block in 4 dogs. The maximally ablated area (%) of the atrioventricular conduction system in serial histologic sections from dogs with these conditions was 69%, 75%, 89.5%, 95% and 99.5%, respectively. The number of intact conduction cells at the maximally ablated site varied from 6 to 30 in the four cases of incomplete AV block. The mean ablated volume (%) of either the AV node or penetrating His bundle correlated roughly with the degree of AV block. The ablated lesions were well demarcated and almost replaced by dense fibrous tissue at 4 weeks. Interruption (3 dogs) or thinning (1 dog) of the endocardial elastic lamellae was detected, in association with endocardial thickening (mean 913 μm). Endocardial thrombi were found in 3 dogs (2 fresh, 1 organized). We conclude that radiofrequency catheter ablation does not cause severe complicated lesions. Several possible conditions for creating chronic incomplete AV block are discussed. Acta Pathol Jpn 41: 487–498, 1991.     

High-Density SNP genotyping defines 17 distinct haplotypes of the TNF block in the Caucasian population: implications for haplotype tagging

The region spanning the tumor necrosis factor (TNF) cluster in the human major histocompatibility complex (MHC) has been implicated in susceptibility to numerous immunopathological diseases, including type 1 diabetes mellitus and rheumatoid arthritis. However, strong linkage disequilibrium across the MHC has hampered the identification of the precise genes involved. In addition, the observation of "blocks" of DNA in the MHC within which recombination is very rare, limits the resolution that may be obtained by genotyping individual SNPs. Hence a greater understanding of the haplotypes of the block spanning the TNF cluster is necessary. To this end, we genotyped 32 human leukocyte antigen (HLA)-homozygous workshop cell lines and 300 healthy control samples for 19 coding and promoter region SNPs spanning 45 kb in the central MHC near the TNF genes. The workshop cell lines defined 11 SNP haplotypes that account for approximately 80% of the haplotypes observed in the 300 control individuals. Using the control individuals, we defined a further six haplotypes that account for an additional 10% of donors. We show that the 17 haplotypes of the "TNF block" can be identified using 15 SNPs.     

腹腔镜对102例女性不孕症诊治的评价分析

目的探讨腹腔镜检查术对女性不孕症的诊治价值。方法回顾性分析腹腔镜检查的102例女性不孕症患者（术后随访2年）,对腹腔镜诊治的结果进行评价。结果镜下诊断盆腔各种病变101例（99.02%）,未发现异常1例（0.08%）。其中输卵管因素54例,子宫内膜异位症34例,卵巢异常8例,子宫异常5例,其他1例。术后随访2年,其妊娠率分别为：输卵管异常31.50%（17/54）,子宫内膜异位症38.24%（13/34）,卵巢异常12.5%（1/8）。结论输卵管因素和子宫内膜异位症是导致女性不孕的主要因素。腹腔镜对诊治输卵管性不孕和子宫内膜异位症,具有快速,准确,可靠,损伤小的特点。     

ACh and 5-HT stimulated thermogenesis at different core temperatures in the He-Cold hypothermic hamster

Hamsters in deep experimentally induced hypothermia, at body temperatures between 7 degrees C and 11.5 degrees C, were microinjected with 5-HT and ACh at brain sites in the anterior-preoptic area of the hypothalamus (AH/POA). ACh or 5-HT was injected into an AH/POA site at different starting core temperatures in different groups of hypothermic hamsters. Colonic temperatures (Tc) were maintained, following He-Cold induction, in a temperature controlled environmental chamber and measured with a YSI thermister probe and YSI telethermometer. Injections of either 5-HT or ACh at Tc's between 7.0 degrees C and 9.0 degrees C elicited only modest increases in Tc i.e., 0.3 degrees C--0.6 degrees C, respectively. As Tc increased, however, to ranges between 9.1 degrees C--10.0 degrees C and in different animals to greater than 10 degrees C both ACh and 5-HT at the same sites elicited significant increases in Tc, 1.5 degrees C for 5-HT and 2.2 degrees C for ACh compared to saline injections. These data suggest that at the lowest Tc's we are observing a "cold block" of temperature sensitive sites in the AH/POA. Increasing the starting Tc beyond 9.0 degrees C however, evokes significant increases in heat-gain following AH/POA injection of either ACh or 5-HT. These data are consistent with Myers' observations concerning the organization of heat-gain mechanisms at AH/POA sites. In addition, they suggest that both the afferent limb of the heat-gain circuit (5-HT) and the efferent limb of the circuit (ACh) are functionally impaired when Tc is close to the physiological limit in the He-Cold hypothermic hamster.     

Prevalence and prognostic significance of cardiac arrhythmias detected by ambulatory electrocardiography in subjects 85 years of age

24 hour ambulatory electrocardiography was performed in a representativegroup of people born in 1897. Out of 73 people included in thestudy, 22 were without known heart disease, 15 had definiteischaemic heart disease (IHD) and 36 symptoms of possible cardiacorigin. An R-R interval in excess of 2000 ms was seen in only3 subjects and Wenckebach A-V block in only one. One subjectwithout a history of syncope had a nocturnal episode of completeA-V block with an escape interval of 8000 ms. The most strikingdifference between healthy subjects and patients with IHD wasthe higher number of patients with more than 1000 ventricularpremature beats (VPBs) per 24 hour and ventricular coupletscompared with the number of healthy subjects with such findings.At follow-up two years later 11% had died, with the highestmortality in patients with IHD (33%), and out of 8 patientswith IHD who had more than 1000 VPBs per 24 hour, 4 (50%) haddied compared with only one (14%) of those with less than 1000VPBs. Our results seem to indicate that more than 1000 VPBsper 24 hour is a very unusual finding in healthy 85 year oldindividuals. When it occurs in very old people, it is usuallyin connection with IHD, and in this setting it signifies a poorprognosis.     

乳腺癌改良根治术中应用超声引导下TPVB复合全身麻醉对患者术后认知功能的影响

目的：探讨乳腺癌改良根治术中应用超声引导下胸椎旁神经阻滞（TPVB）复合全身麻醉对患者术后认知功能的影响。方法：选择信阳市中心医院2020年1月至2021年12月期间收治的56例乳腺癌改良根治术患者,以随机数字表法分为观察组（超声引导下TPVB联合全身麻醉）和对照组（全身麻醉）,各28例。比较两组患者的麻醉前（T0）、切皮时（T1）、手术开始60 min(T2)、术毕时（T3）的血流动力学指标变化情况,记录术中两组患者的麻醉药物用量,记录术前、术后1 d两组患者的神经功能状况,比较两组术后不良反应发生情况。结果：T1～T3时观察组患者的平均动脉压（MAP）、心率（HR）与T0时比较,差异无统计学意义（P> 0.05）;T1～T3时对照组患者的MAP、HR高于T0时,差异具有统计学意义（P <0.05）;T1～T3时观察组患者的MAP、HR低于同时段对照组,差异具有统计学意义（P <0.05）。观察组患者的术中丙泊酚、瑞芬太尼用量低于对照组,差异具有统计学意义（P <0.05）。术后1 d两组患者的简易智力状态检查量表（MMSE）评分均低于术前,且术后1 d观察组...     

永久起搏电极植入途径及起搏类型的探讨

目的评价起搏电极的植入途径及永久起搏器的类型.方法选择1987～1999年安置的80例永久起搏器患者.结果经颈外静脉植入电极6例,手术时间为256±75分;经头静脉植入电极48例,手术时间为247±65分(P＞0.05);经锁骨下静脉途径植入电极26例,手术时间为118±35分(P均＜0.01).其中,AAI型3例(4%),DDD型5例(6%),VVI型72例(90%).结论经锁骨下静脉植入起搏电极,方法简单,组织损伤小,手术时间短,优于其它途径.VVI型起搏器在我国仍然是主要使用的起搏器.     

急性心肌梗塞伴右束支传导阻滞的临床意义

目的 :评价急性心肌梗塞 (AMI)患者并发右束支传导阻滞 (RBBB)的临床特征及预后意义。方法 :观察了我院 1995年 1月至 2 0 0 0年 7月 339例住院AMI患者的心电图、血清磷酸肌酸激酶 (CK)及其同工酶 (CK MB)的峰值水平、严重并发症及死亡率。结果 :5 4例AMI并发RBBB患者 (占 15 .93% )预后明显差于无并发RBBB者 ,表现为血清CK及CK MB浓度更高 ,严重心脏事件发生率及死亡率增高 ,经统计学处理两组间比较有显著性差异 (P<0 .0 1)。结论 :AMI患者并发RBBB通常是心肌大面积梗死的表现 ,RBBB是一个独立的可判断预后的指标 ,冠脉的再灌注可影响传导的可逆性 ,可预防束支传导阻滞的发生或限制其持续时间 ,积极的心脏介入性治疗及血管重建可改善预后。