普通型与重型新型冠状病毒肺炎患者临床分析

目的 分析严重急性呼吸综合征冠状病毒2（severe acute respiratory syndrome coronavirus 2, SARS-CoV-2）感染引起新型冠状病毒肺炎（coronavirus disease 2019, COVID-19）患者普通型与重型的流行病学、实验室检查及影像学特征,为COVID-19防治提供经验依据。 方法 选取2020年1—2月在池州市人民医院、皖南医学院第一附属医院隔离病房收治的23例COVID-19患者为研究对象。将患者分为普通型（19例）、重型（4例）两组,根据两组流行病学、血生化、血常规等实验室数据,比较和分析两组患者血清中上述各指标变化的规律及其与疾病预后的关系。 结果 COVID-19患者普通型与重型无性别与年龄差异,2例重型患者合并有基础疾病,为2型糖尿病;重型患者发病至就诊的平均时间为（10.00±6.67）d,长于普通型（3.73±2.97）d（P<0.05）;实验室结果显示重型患者的淋巴细胞比值为（10.20±7.19）%,低于普通型患者淋巴细胞比值为（28.06±9.47）%（P<0.05）;两组的CRP结果,普通型为(16.46±19.24)mg/L,重型为(73.65±44.96)mg/L（P<0.05）;COVID-19患者典型的CT表现为单发或多发的斑片状磨玻璃影,伴有小叶间隔增厚。疾病进展为重型时病灶增多、范围扩大,磨玻璃影与实变影或条索影共存,部分重症患者表现为双肺弥漫性病变。 结论 对于新型冠状病毒肺炎患者如果合并有基础病,就诊时间长;实验室检查示淋巴细胞绝对值下降,CRP升高等,建议短期复查HRCT,防止普通型向重型发展。     

鞘内注射治疗髓母细胞瘤研究进展

髓母细胞瘤是儿童原发中枢神经系统最常见的恶性肿瘤,约占儿童颅内肿瘤的20%。髓母细胞瘤主要累及小脑蚓部,具有很强的脑脊液播散倾向,目前仍以手术为主结合化疗及放疗的综合治疗为主要治疗方式。其原发部位及脑脊液播散特点,使得鞘内注射成为特殊治疗手段,但是患儿却要长期忍受此种方式给生理和心理造成的巨大影响,因而积极寻求既能靶向杀伤肿瘤细胞、毒副反应又小的新的辅助治疗手段更具临床意义。     

血栓形成易感基因芯片的研制及效果评价

目的：探讨血栓形成易感基因芯片的研制方法及初步临床验证,建立一种快速且高通量检测血栓形成易感基因突变的方法。方法：根据GenBank上已发表的血栓形成易感基因序列,将设计好的参照探针和特异性探针点置于醛基化处理的玻片上,经紫外交联后固定,制成血栓形成易感基因芯片。以阳性参考品（各检测位点突变型和正常型基因）和阴性参考品（双蒸水）为模板,经PCR反应后与芯片进行杂交,对基因芯片的有效性进行检测。以靶序列经过测序验证的人类基因组DNA为模板,经PCR反应后芯片进行杂交,检测基因芯片的特异度和灵敏度,并对来自吉林、河南和云南3个地区的健康受试者150人和有不明原因血栓性疾病家族史的血栓患者24例进行临床验证。分析指标为检测相应位点的杂交信号强度。结果：以阳性参考品和阴性参考品为模板进行杂交,相应位点出现特异性的杂交信号,说明基因芯片检测位点有效。用于检测选定突变位点的基因芯片均有特异性的杂交信号,说明基因芯片的特异性良好。标准基因组DNA逐级稀释后检测基因芯片的灵敏度为50~100 mg·L^-1。临床验证结果,在健康受试者150人中8人检出血栓形成易感基因突变,在有不明原因血栓性疾病家族史的血栓患者24例中20例检出血栓形成易感基因突变,该芯片对不明原因血栓性疾病家族史的血栓患者血栓形成易感基因突变检出率明显高于健康受试者（P<0.05）。结论：研制的血栓形成易感基因芯片具有良好的特异度和灵敏度,对血栓形成易感基因有较高的检出率,在血栓性疾病的早期诊断和易感风险评估中具有潜在价值。     

Arenium ions are not obligatory intermediates in electrophilic aromatic substitution

Our computational and experimental investigation of the reaction of anisole with Cl₂ in nonpolar CCl₄ solution challenges two fundamental tenets of the traditional S_EAr (arenium ion) mechanism of aromatic electrophilic substitution. Instead of this direct substitution process, the alternative addition–elimination (AE) pathway is favored energetically. This AE mechanism rationalizes the preferred ortho and para substitution orientation of anisole easily. Moreover, neither the S_EAr nor the AE mechanisms involve the formation of a σ-complex (Wheland-type) intermediate in the rate-controlling stage. Contrary to the conventional interpretations, the substitution (S_EAr) mechanism proceeds concertedly via a single transition state. Experimental NMR investigations of the anisole chlorination reaction course at various temperatures reveal the formation of tetrachloro addition by-products and thus support the computed addition–elimination mechanism of anisole chlorination in nonpolar media. The important autocatalytic effect of the HCl reaction product was confirmed by spectroscopic (UV-visible) investigations and by HCl-augmented computational modeling.Interest in the chemistry of electrophilic aromatic substitution reactions continues because of their widespread application for the production of a great variety of chemicals and materials (1–4). Electrophilic substitution, considered to be the most characteristic reaction of aromatic systems, is typically described in textbooks, monographs, and reviews by the two-stage S_EAr mechanism depicted in Fig. 1 (5–11). Arenium ion (σ-complex) intermediates are often ascribed to Wheland (9) inaccurately, since Pfeiffer and Wizinger (10) laid out the principles of such species for bromination in 1928. Following Brown and Pearsall (11), they are widely believed to have σ-complex structures. Arenium ions (σ-complexes) (9–11) are widely accepted to be obligatory intermediates and are used to rationalize ortho/para vs. meta position orientation preferences (6–11).Open in a separate windowFig. 1.Typical depiction of the arenium ion mechanism for S_EAr reactions.We now reinforce our challenges (12, 13) of this conventional “reaction mechanism paradigm” (14) by a combined computational and experimental study of the facile chlorination of anisole (methoxybenzene) with Cl₂ in CCl₄ solution (15, 16). We find that Fig. 1 is not the favored pathway. Instead, addition reactions of Cl₂ to anisole have the lowest activation energies (Fig. 2). Ready HCl elimination from the initially formed adducts leads to ortho- and para-chloroanisole as the predominate products. This addition–elimination (AE) mechanism (the historical antecedent to Fig. 1) (17–26) predicts the same positional orientation as the usually assumed direct substitution (“S_EAr”) alternative. Instead of this classic S_EAr mechanism (Fig. 1), we find that direct concerted substitution, not involving an arenium ion, σ-complex (“Wheland”) (9–11) intermediate, competes energetically with the AE route. Like some earlier computational studies on aromatic substitution (12, 13, 27, 28) (Rzepa H, www.ch.imperial.ac.uk/rzepa/blog/?p=2423, accessed March 10, 2013), our study finds no such intermediates in the direct substitution of anisole by Cl₂. A concerted mechanism without an arenium ion intermediate was computed at some levels for the related arene nitrosation, but reaction medium and counter ion effects were not considered. Gwaltney et al. (28) reported a single concerted transition state after reoptimizing all saddle points at CCSD(T)/6-31G(d,p) and modeling bulk solvation by the Onsager approximation, and Rzepa (www.ch.imperial.ac.uk/rzepa/blog/?p=2423, accessed March 10, 2013) also found a concerted transition state including a trifluoroacetate counterion. Instead, one-step reactions via single transition states take place (Fig. 2). Our experimental investigations of the chlorination of anisole in CCl₄ solution revealed tetrachloro by-products, which must have arisen by further reaction of intermediate dichloro-adducts. Both our UV-visible (UV-VIS) spectroscopic investigation and our theoretical modeling of this reaction clearly verified the autocatalytic effect of the HCl by-product, in harmony with Andrews and Keefer’s (29, 30) early experimental kinetic studies of the chlorination of arenes, which found that HCl reduces the activation barriers significantly.Open in a separate windowFig. 2.The HCl-catalyzed concerted and addition–elimination pathways of para-chlorination of anisole in nonpolar media.We also applied reliable theoretical methods to model a typical experimental example of the highly investigated S_EAr electrophilic aromatic halogenations, the electrophilic chlorination of anisole by molecular chlorine in simulated CCl₄ solution (15, 16). Although the elucidation of the classic S_EAr mechanism [Fig. 1, involving the initial formation of a π-complex, followed by a transition state leading to a σ-complex (arenium) intermediate in the rate-controlling stage, and, finally, proton loss from the ipso-position leading to the reaction product] is considered to be a triumph of physical organic chemistry (1, 31–37), an alternative addition–elimination pathway leading to substitution products has been discussed since the 19th century (19–26, 38, 39). Nevertheless, it is commonly believed that the classic multistep S_EAr mechanism involving the formation of a σ-complex intermediate in the rate-controlling stage is the only mechanistic route to aromatic substitution products. Our present and previous (12, 13) results challenge the generality of such traditional interpretations. Although the initial stages of the alternative AE route seem unattractive because aromaticity is lost, many arenes are known experimentally to give addition products in considerable amounts (19–26, 38, 39). Thus, de la Mare (21, 25, 38, 39) demonstrated the formation of halogen adduct intermediates. Polybenzenoid hydrocarbons (PBHs) react with halogens to give isolable addition products, which then give substitution products easily by hydrogen halide elimination (23). Our computational investigations of arene bromination with molecular bromine (12) and sulfonation with SO₃ (13) provided clear evidence that the mechanisms of the inherent substitution reactions (i.e., uncatalyzed, gas phase, or weakly solvated) are concerted and do not involve the conventional σ-complex (or any other) intermediates. Moreover, the energetics of the bromination processes document the significance of competition between AE and direct substitution mechanisms leading to the same substitution products. Thus, the computed barrier in a simulated nonpolar (CCl₄) medium is 4 kcal/mol lower for Br₂ addition to benzene (followed by HBr elimination) than that for the direct substitution pathway to bromobenzene (12).Previous theoretical studies of electrophilic aromatic halogenation processes have been based on the classic S_EAr mechanism, involving arenium ion intermediates (Fig. 1). Osamura et al.’s (40) Hartree-Fock computations of the AlCl₃-catalyzed electrophilic aromatic chlorination mechanism found an initial π-complex, a transition state preceding the intermediate σ-complex, and a second transition state leading to final products. Aluminum chloride was important as a Lewis acid catalyst throughout the process. AlCl₃ coordination polarizes Cl₂ and thereby assists its reaction with the arene. Rasokha and Kochi (41) considered the interaction of Br₂ with benzene and toluene in detail in their survey of theoretical and experimental data on the prereactive charge-transfer complexes in electrophilic aromatic substitutions. They argued that the structures and properties of the prereactive complexes provide important mechanistic insights for the S_EAr reactions. Wei et al.’s (42) theoretical study of the iodination of anisole by iodine monochloride at the B3LYP/6-311G* and MP2//B3LYP/6-311G* levels (B3LYP, Becke''s three parameter hybrid functional, using the Lee-Yang-Parr correlation functional; MP2, second order Møller-Plesset perturbation theory computations) found that the highest energy transition state precedes the formation of an intermediate, which they interpreted to be a σ-complex. Instead, the structure of this complex represents a protonated iodobenzene. Volkov et al.’s MP2/LANL2DZ(d)+ study (43) of the chlorination of benzene established that dimers of group 13 metal halides catalyzed the processes more effectively. Optimized geometries of π- and σ-complexes as well as transition structures were reported. Theoretical investigations by Ben-Daniel et al. (44) and by Filimonov et al. (45) of the chlorination of benzene with Cl₂ (and other related processes) reported structural details of transition states purported to lead to the chlorobenzene product. Our reinvestigations revealed errors in major suppositions of both these studies. Our IRC computations show clearly that the transition states in question lead to 1,2 Cl₂–benzene addition products (rather than to chlorobenzene). Zhang and Lund (46) investigated the neat chlorination of toluene by Cl₂ experimentally and theoretically at B3LYP/cc-pVTZ(-f) [cc-pVTZ(-f), correlation consistent polarized triple-zeta without f-functions basis set]. Although we verified their reported geometry of the concerted transition state (figure 6 in ref. 46), our stability check revealed that its wavefunction is unstable. This casts doubt on their conclusions because of the homolysis vs. heterolysis issues. In contrast, all wavefunctions in our paper were checked and all are stable. Most prior theoretical studies of S_EAr halogenations did not consider the connections between transition states, intermediates, and products explicitly, as we have done.Experimental findings not always have been in accord with the prevailing mechanistic assumption for aromatic halogenation: that arenium ion formation is the rate-limiting step. Thus, Olah et al. (47), Kochi and coworkers (48), and Fukuzumi and Kochi (49) have emphasized that substrate and positional selectivity are inconsistent (e.g., low toluene/benzene reactivity ratios but high toluene ortho–para vs. meta regiospecificity) for some electrophiles under certain conditions. This disparity indicates the existence of at least one other mechanistic pathway. It has been suggested that π-complexes may control product formation. Olah et al.’s (47) kinetics of the ferric chloride-catalyzed bromination of benzene and alkyl benzenes provided strong evidence for low substrate selectivity in the rate-determining step, which precedes the formation of a σ-complex intermediate (Fig. 1). High positional selectivity is governed by the transition state associated with the second step of the reaction.However, our earlier study (50) examined the possible participation of π-complexes in the key mechanistic steps of S_EAr bromination reactions in detail but found no link between the energy of formation of these complexes and the overall reactivity. Although there is no doubt that π-complexes form easily (via essentially barrierless processes) in most S_EAr reactions after mixing the electrophile and the aromatic substrate, it is unlikely that these low-energy “bystander” structures influence rates of S_EAr reactions significantly. Thus, the lack of accord between substrate and positional selectivity, established by Olah et al. (47), Kochi and coworkers (48), and Fukuzumi and Kochi (49) may be due to other mechanistic differences. De la Mare and Bolton (21) and de la Mare (51) have stressed the plurality of aromatic substitution mechanisms, depending on the substrate and the conditions.Reactive substrates are known to undergo uncatalyzed aromatic substitution in nonpolar solvents at room temperature. Thus, our computational investigations modeled Watson’s careful experiments on the chlorination of anisole in CCl₄ at 25 °C (15, 16). His low conversion (25%) conditions for chlorophenol permitted more accurate determination of the initial product ratios (and avoided further Cl₂ additions to 4-chloroanisole, which ultimately gave 1,3,4,5,6-pentachloro-4-methoxycyclohexene). After introduction of gaseous Cl₂ into a CCl₄ solution of anisole for 1 h, the products were 4-chloroanisole (76%), 2-chloroanisole (13.6%), 2,6-dichloro anisole (2.1%), 2,4-dichloroanisole (3.0%), and 2,4,6-trichloroanisole (0.4%).Analogous chlorinations of phenol, 2-methylphenol, and 2-chlorophenol in CCl₄ also have been carried out with high conversion rates at the reflux temperature (79 °C) (16). Chlorination of phenol with Cl₂ in CCl₄ has been reported by other groups (52, 53).     

Improved synthesis of key intermediate of grayanotoxin III

A concise improved synthesis of the key intermediate for the synthesis of grayanotoxin III was realized in the present study, featuring a tandem reaction of Michael addition-esterification, Mukaiyama hydration and Mukaiyama dehydrogenaiton.     

多西环素与平阳霉素治疗儿童大囊型淋巴管畸形的比较研究

目的比较注射用盐酸多西环素与注射用盐酸平阳霉素治疗儿童大囊型淋巴管畸形的临床疗效。方法选取2012年1月—2017年6月天津市儿童医院治疗的60例大囊型淋巴管畸形的患儿作为研究对象,将患儿根据治疗药物的不同分为对照组和治疗组,每组各30例。对照组在DSA透视下经皮注射注射用盐酸平阳霉素8 mg、碘海醇注射液4 mL与生理盐水4 mL组成的混合液,完成后摄片,平阳霉素用量为从病变中吸出体积的1/3～1/2,但总量不超过8 mg。治疗组在DSA透视下经皮注射注射用盐酸多西环素0.1 g、碘海醇注射液2.5 mL与生理盐水2.5mL组成的混合液,完成后摄片,多西环素用量为从病变中吸出体积的1/3～1/2,但总量不超过250 mg。所有患儿均于治疗后4周随访,4周后若患儿未达治愈标准可重复进行,3～5次为1个疗程,术后随访18个月。观察两组患者的临床疗效,比较两组瘤体体积变化情况和不良反应情况。结果治疗后,对照组和治疗组总有效率分别为80.0%、96.7%,两组比较差异有统计学意义(P0.05)。治疗后,两组病变瘤体体积均显著减少,同组治疗前后比较差异具有统计学意义(P0.05);治疗后,治疗组病变瘤体体积显著小于对照组,两组比较差异具有统计学意义(P0.05)。治疗期间,对照组和治疗组的不良反应发生率分别为33.3%、10.00%,两组比较差异具有统计学意义(P0.05)。结论多西环素治疗儿童大囊型淋巴管畸形的疗效优于平阳霉素,可以显著减少病变瘤体体积,安全性高,具有一定的临床推广应用价值。