BACKGROUND & AIMS: :Neutralizing antibody titers of 47 infants whose mothers sustained measles (measles group) and 70 whose mothers were vaccinated (vaccine group) were compared at birth, 4 and 8 months of age. All children had antibodies at birth and 88% at 4 months. At 8 months, 49% had antibodies in the measles group and 15% in the vaccine group (P < 0.001). The geometric mean titers were significantly lower in the vaccine group than in the measles group and the difference corresponded to the antibody loss occurring in only 1.5 months of life. This small difference may reflect past exposure to wild virus of many vaccinated mothers.

背景与目标： : 比较了47名母亲患有麻疹的婴儿 (麻疹组) 和70名母亲接种了疫苗的婴儿 (疫苗组) 的中和抗体滴度。出生，4和8个月大。所有儿童在出生时具有抗体，并在4个月时88%。在8个月时，49% 在麻疹组中有抗体，在疫苗组中有15% (P <0.001)。疫苗组的几何平均滴度显着低于麻疹组，并且该差异对应于仅在生命的1.5个月内发生的抗体丢失。这种微小的差异可能反映了许多接种疫苗的母亲过去暴露于野生病毒。

BACKGROUND & AIMS: :6-Pyruvoyltetrahydropterin synthase (PTPS) catalyzes the second step of tetrahydrobiopterin (BH4) synthesis. We previously identified PTPS orthologs (bPTPS-Is) in bacteria which do not produce BH4. In this study we disrupted the gene encoding bPTPS-I in Synechococcus sp. PCC 7942, which produces BH4-glucoside. The mutant was normal in BH4-glucoside production, demonstrating that bPTPS-I does not participate in BH4 synthesis in vivo and bringing us a new PTPS ortholog (bPTPS-II) of a bimodular polypeptide. The recombinant Synechococcus bPTPS-II was assayed in vitro to show PTPS activity higher than human enzyme. Further computational analysis revealed the presence of mono and bimodular bPTPS-II orthologs mostly in green sulfur bacteria and cyanobacteria, respectively, which are well known for BH4-glycoside production. In summary we found new bacterial PTPS orthologs, having either a single or dual domain structure and being responsible for BH4 synthesis in vivo, thereby disclosing all the bacterial PTPS homologs.

背景与目标： : 6-丙酮酸基四氢蝶呤合酶 (PTPS) 催化四氢生物蝶呤 (BH4) 合成的第二步。我们先前在不产生bh4的细菌中鉴定了PTPS直系同源物 (bPTPS-Is)。在这项研究中，我们破坏了Synechococcus sp. PCC 7942中编码bPTPS-I的基因，该基因产生了BH4-glucoside。该突变体在BH4-glucoside生产中是正常的，表明bPTPS-I在体内不参与BH4合成，并为我们带来了双峰多肽的新PTPS直系同源物 (bPTPS-II)。在体外测定了重组Synechococcus bptp-II，显示PTPS活性高于人酶。进一步的计算分析表明，分别在绿色硫细菌和蓝细菌中存在单和双模bPTPS-II直系同源物，这在BH4-glycoside生产中是众所周知的。总而言之，我们发现了新的细菌PTPS直系同源物，具有单个或双结构域结构，并负责体内BH4的合成，从而公开了所有细菌PTPS同源物。

BACKGROUND & AIMS: PURPOSE OF REVIEW:Radiotherapy is very effective in local control of Hodgkin's lymphoma. Unfortunately, long-term survivors exhibit an excess of life-threatening radiation-related late side effects. Consequently, there have been calls to cease the use of radiation in the primary treatment of Hodgkin's lymphoma, although there is also support for the judicious use of combined modality treatment. RECENT FINDINGS:Most patients treated for Hodgkin's lymphoma are being cured with modern approaches. Recent publications confirm the superior efficacy of combined modality treatment over chemotherapy alone, but the initial gain in cure rate may be outweighed by late deaths due to various treatment-related diseases. Many patients may already be cured by chemotherapy alone. Classical risk factors can be used to distinguish favourable and unfavourable subgroups of patients with Hodgkin's lymphoma, but these risk factors cannot predict outcome in individual cases. A simple test to predict the likelihood of cure in individual patients would be of great benefit. Fluoro-deoxyglucose-PET scan investigation holds this promise. SUMMARY:The present review deals with the role of radiation therapy in the treatment of Hodgkin's lymphoma.

背景与目标：

BACKGROUND & AIMS: :It is well-recognised that steady-state isometric muscle force is decreased following active shortening (force depression, FD) and increased following active stretch (force enhancement, FE). It has also been demonstrated that passive muscle force is increased following active stretch (passive FE). Several studies have reported that FD increases with shortening amplitude and that FE and passive FE increase with stretch amplitude. Here, we investigate whether these trends continue with further increases in shortening or stretch amplitude. Experiments were performed using in situ cat soleus muscles (n=8 for FD; n=7 for FE and passive FE). FD, FE and passive FE were measured after shortening or stretch contractions that covered as wide a range of amplitudes as practically possible without damaging the muscles. FD increased approximately linearly with shortening amplitude, over the full range of amplitudes investigated. This is consistent with the hypothesis that FD arises from a stress-induced inhibition of crossbridges. FE increased with stretch amplitude only up to a point, and then levelled off. Passive FE, and the transient increase in force at the end of stretch, showed relationships to stretch amplitude that were qualitatively very similar to the relationship for FE, increasing only until the same critical stretch amplitude had been reached. We conclude that FE and passive FE do not increase with stretch amplitude under all circumstances. This finding has important consequences for determining the mechanisms underlying FE and passive FE because any mechanism that is proposed to explain them must be able to predict it.

背景与目标： : 众所周知，主动缩短 (力降低，FD) 后，稳态等距肌肉力降低，主动拉伸 (力增强，FE) 后，稳态等距肌肉力增加。还已证明，主动拉伸 (被动FE) 后，被动肌肉力量会增加。一些研究报告说，FD随缩短幅度而增加，FE和被动FE随拉伸幅度而增加。在这里，我们研究这些趋势是否随着缩短或拉伸幅度的进一步增加而继续。使用原位猫比目鱼肌进行实验 (FD为n = 8; FE和被动FE为n = 7)。在缩短或拉伸收缩后测量FD，FE和被动FE，这些收缩实际上覆盖了尽可能宽的振幅范围，而不会损坏肌肉。在所研究的整个振幅范围内，FD随振幅的缩短而近似线性增加。这与FD由应力诱导的交叉桥抑制引起的假设是一致的。FE仅随拉伸幅度增加到一个点，然后趋于平稳。被动FE和拉伸结束时的瞬时力增加显示出与拉伸幅度的关系，在质量上与FE的关系非常相似，仅在达到相同的临界拉伸幅度之前才增加。我们得出的结论是，在所有情况下，FE和被动FE都不会随拉伸幅度而增加。这一发现对于确定FE和被动FE的潜在机制具有重要的影响，因为提出的任何解释它们的机制都必须能够预测它。

BACKGROUND & AIMS: BACKGROUND:Flow cytometric basophil activation tests have been developed as cellular tests for in vitro diagnosis of IgE-mediated reactions. Different activation markers (CD63 or CD203c) with distinct ways of regulation have been used after stimulation with various allergens. OBJECTIVE:It was the aim of the present study to compare basophil activation tests by measuring both CD63 and CD203c upregulation in patients with insect venom allergy. MATERIALS AND METHODS:43 patients with a history of insect venom anaphylaxis were examined. A careful allergy history was taken, and skin tests and determination of specific IgE-antibodies were performed. Basophil activation tests (BAT) using CD63 or CD203c expression were done after stimulation with different concentrations of bee and wasp venom extracts. 25 healthy subjects with negative history of insect venom allergy were studied as controls. RESULTS:The CD203c protocol showed a slightly higher sensitivity than the CD63 protocol (97% vs. 89%) with regard to patients' history. The magnitude of basophil response was higher with CD203c in comparison to CD63 for both insect venoms. Specificity was 100% for the CD63 protocol and 89% for the CD203c protocol with regard to controls with negative history and negative RAST. CONCLUSION:These results support the reliability of basophil activation tests using either CD63 or CD203c as cellular tests in the in vitro diagnosis of patients with bee or wasp venom allergy with a slightly higher sensitivity for the CD203c protocol.

背景与目标：

BACKGROUND & AIMS: BACKGROUND:Previous studies revealed increased parietal late positive potentials (LPPs) in response to spider pictures in spider phobic individuals. This study searched for basic features of fear-relevant stimuli by investigating whether schematic spider images are sufficient to evoke differential behavioral as well as differential early and late ERP responses in spider phobic, social phobic (as a clinical control group), and non-phobic control participants. METHODS:Behavioral and electrophysiological correlates of the processing of schematic spider and flower images were investigated while participants performed a color (emotional Stroop) and an object identification task. Stimuli were schematic pictures of spiders and flowers matched with respect to constituting visual elements. RESULTS:Consistent with previous studies using photographic spider pictures, spider phobic persons showed enhanced LPPs when identifying schematic spiders compared to schematic flowers. In addition, spider phobic individuals showed generally faster responses than the control groups. This effect was interpreted as evidence for an increased general behavioral hypervigilance in this anxiety disorder group. Furthermore, both phobic groups showed enhanced P100 amplitudes compared to controls, which was interpreted as evidence for an increased (cortical) hypervigilance for incoming stimuli in phobic patients in general. Finally, all groups showed faster identification of and larger N170 amplitudes in response to schematic spider than flower pictures. This may reflect either a general advantage for fear-relevant compared to neutral stimuli, or might be due to a higher level of expertise in processing schematic spiders as compared to the more artificially looking flower stimuli. CONCLUSION:Results suggest that schematic spiders are sufficient to prompt differential responses in spider-fearful and spider-non-fearful persons in late ERP components. Early ERP components, on the other hand, seem to be modified by anxiety status per se, which is consistent with recent theories on general hypervigilance in the anxiety disorder spectrum.

背景与目标：

BACKGROUND & AIMS: :The alkenyldiarylmethanes (ADAMs) are a unique class of non-nucleoside reverse transcriptase inhibitors that have potential value in the treatment of HIV/AIDS. However, the potential usefulness of the ADAMs is limited by the presence of metabolically labile methyl ester moieties. A series of novel ADAMs were therefore designed and synthesized in order to replace the metabolically labile methyl ester moieties of the existing ADAM lead compounds with hydrolytically stable, fused isoxazolone, isoxazole, oxazolone, or cyano substituents on the aromatic rings. The methyl ester and methoxy substituents on both of the aromatic rings in the parent compound 1 were successfully replaced with metabolically stable moieties with retention of anti-HIV activity and a general decrease in cytotoxicity.

背景与目标： : 烯基二芳基甲烷 (ADAMs) 是一类独特的非核苷类逆转录酶抑制剂，在治疗HIV/AIDS中具有潜在价值。然而，ADAMs的潜在用途受到代谢不稳定的甲酯部分的存在的限制。因此，设计并合成了一系列新型的ADAMs，以便用水解稳定的，稠合的异恶唑酮，异恶唑，恶唑酮或芳环上的氰基取代基代替现有ADAM铅化合物的代谢不稳定的甲酯部分。母体化合物1中两个芳环上的甲酯和甲氧基取代基已成功地被代谢稳定的部分取代，并保留了抗HIV活性，细胞毒性普遍降低。

BACKGROUND & AIMS: Etoposide produces reversible inhibition of topoisomerase II, leading to cleavage of DNA, and thereby has an antitumor effect. This mechanism suggests that the longer treatment is continued, the greater the antitumor effect will be. In the present study, both therapeutic and adverse effects of long-term treatment with low-dose oral etoposide were studied in 29 patients aged > or = 65 years with non-Hodgkin's lymphoma (NHL) for whom standard chemotherapy was not effective or refractory. These patients received etoposide at a dose of 50 mg/d for as long as possible. Treatment was continued until white blood cell count decreased to < or = 2,000/microL or the platelet count decreased to < or = 5 x 10(4)/microL. According to the World Health Organization (WHO) criteria of therapeutic effects, 6 (20.7%) of the 29 patients achieved complete remission and 13 patients (44.8%) had partial remission, for a response rate of 65.5%. Adverse effects of > or = grade 3 included leukopenia in 24 patients (82.8%) and anemia in 7 (24.1%). Granulocyte colony-stimulating factor (G-CSF) was given in combination with etoposide to eight patients because of leukopenia (granulocyte count < or = 1,000/microL). In view of the excellent subjective tolerance, low incidence of serious adverse effects, and good activity, single agent oral etoposide given continuously over prolonged periods represents a useful treatment for elderly patients with NHL.

背景与目标： 依托泊苷产生拓扑异构酶II的可逆抑制，导致DNA裂解，从而具有抗肿瘤作用。这种机制表明，持续治疗的时间越长，抗肿瘤作用就越大。在本研究中，对29例年龄> 或 = 65岁的非霍奇金淋巴瘤 (NHL) 患者进行了低剂量口服依托泊苷长期治疗的治疗和不良反应的研究，这些患者的标准化疗无效或难治性。这些患者尽可能长时间地接受依托泊苷50 mg/d的剂量。继续治疗直到白细胞计数降低至 <或 = 2,000/microL或血小板计数降低至 <或 = 5 × 10(4)/microL。根据治疗效果的世卫组织标准，29例患者中有6例 (20.7% 例) 完全缓解，13例 (44.8% 例) 部分缓解，缓解率为65.5%。> or = 3级的不良反应包括白细胞减少24例 (82.8%) 和贫血7例 (24.1%)。由于白细胞减少 (粒细胞计数 <或 = 1,000/microL)，将八名患者与依托泊苷联合给予粒细胞集落刺激因子 (g-csf)。鉴于其良好的主观耐受性，低的严重不良反应发生率和良好的活性，长期连续给予单药口服依托泊苷代表了对老年NHL患者的有用治疗。

BACKGROUND & AIMS: OBJECTIVE:To identify reasons why rural general practitioners (GPs) treat a large proportion of patients with a primary psychiatric diagnosis in general beds of their local hospitals, and the barriers encountered when providing this treatment. DESIGN:A postal questionnaire was developed and distributed to a sample of rural GPs, asking about the treatment of patients with an acute mental illness in their local hospital. RESULTS:The majority of GPs agreed that they treat the acutely mentally ill in general beds of their local hospital due to lack of availability of, and inability to gain access to, mental health beds in the larger centres; and also to enable ongoing family involvement and continuity of care. Distance factors were identified as least significant. Barriers to providing care to this group of patients included a perceived lack of support by consultant psychiatrists, confidentiality issues, lack of community mental health workers to provide assistance, aggression levels of patients, inappropriate local hospital setting, and lack of confidence of GPs and general hospital nursing staff. CONCLUSION:Addressing these barriers is necessary if rural Australians are to receive a quality of care that is equal to that received by those located in metropolitan Australia. Continuing research in this area is crucial.

背景与目标：

BACKGROUND & AIMS: :This review describes the assessment of the aortic valve by echocardiography and also the roles that multidetector CT (MDCT) and cardiac magnetic resonance have to play as complimentary imaging modalities. It describes how to resolve apparent discrepancies in grading aortic stenosis and discusses the management of apparently moderate stenosis associated with cardiac symptoms or left ventricular dysfunction. The role of cardiac imaging including three-dimensional (3D) echocardiography and MDCT scanning in the preparation for transcatheter aortic valve implantation and during and after the procedure are described. While echocardiography remains the mainstay of imaging, 3D modalities, notably MDCT, are increasingly useful and a multimodality approach is likely to become established as routine clinical practice.

背景与目标： : 这篇综述描述了超声心动图对主动脉瓣的评估，以及多探测器CT (MDCT) 和心脏磁共振作为互补成像方式所发挥的作用。它描述了如何解决主动脉狭窄分级中的明显差异，并讨论了与心脏症状或左心室功能障碍相关的明显中度狭窄的管理。描述了包括三维 (3D) 超声心动图和MDCT扫描在内的心脏成像在经导管主动脉瓣植入准备以及手术期间和之后的作用。尽管超声心动图仍然是成像的主要手段，但3D模式 (尤其是MDCT) 越来越有用，并且多模态方法可能会被确立为常规临床实践。

BACKGROUND & AIMS: :We reviewed six cases of primary sarcomas requiring scapulectomy within the past 13 years in the Surgery Branch of the National Cancer Institute, Bethesda, Md. Five of these patients returned for evaluation of disease status, evaluation of functional defects as determined by muscle group testing, and assessment of daily living skills and limitations. We demonstrated excellent shoulder function with partial scapulectomy and significant impairment with the additional loss of the glenoid fossa. In addition, we developed a thorough method of postoperative evaluation. Involvement of rehabilitation therapists before and after operatively is integral to this process in preparation for surgery and subsequent treatment.

背景与目标： : 在过去的13年中，我们在马里兰州贝塞斯达的国家癌症研究所外科分支机构中回顾了6例需要进行肩胛骨切除术的原发性肉瘤病例。这些患者中有五名返回以评估疾病状况，评估通过肌肉群测试确定的功能缺陷以及评估日常生活技能和局限性。我们通过部分肩胛骨切除术证明了出色的肩部功能，并通过关节盂窝的额外损失而明显受损。此外，我们开发了一种彻底的术后评估方法。在手术和后续治疗的准备过程中，康复治疗师在手术前后的参与是必不可少的。

BACKGROUND & AIMS: :Porcine enzootic pneumonia (PEP), which is caused by the fastidious bacterium Mycoplasma hyopneumoniae, is one of the most economically important diseases in the pig industry worldwide. Commercial bacterins provide only partial protection; therefore, the development of more efficient vaccines against PEP is necessary. In this study, the cellular and humoral immune responses elicited by DNA and recombinant subunit vaccines based on the P37, P42, P46 and P95 antigens of M. hyopneumoniae were evaluated after the intramuscular inoculation of BALB/c mice. The expression of the cytokines INFγ, TNFα and IL1 was evaluated by real-time RT-PCR in splenocytes from vaccinated mice. All antigens delivered as subunit vaccines, especially P42 and P95, and the pcDNA3/P46 DNA vaccine were able to elicit strong immune responses. These vaccines induced cellular immune responses and the production of antibodies able to react with native M. hyopneumoniae proteins. Because both cellular and humoral immune responses were induced, P42 and P95 are promising candidates for a recombinant subunit vaccine and P46 is a promising candidate for a DNA vaccine against PEP.

背景与目标： : 猪传染性肺炎 (PEP) 是由挑剔的细菌支原体肺炎e引起的，是全球养猪业最重要的经济疾病之一。商业细菌仅提供部分保护; 因此，必须开发针对PEP的更有效疫苗。在这项研究中，在肌内接种BALB/c小鼠后，评估了基于猪肺炎支原体P37，P42，P46和P95抗原的DNA和重组亚基疫苗引起的细胞和体液免疫反应。通过实时rt-pcr评估了免疫小鼠脾细胞中细胞因子inf γ，tnf α 和IL1的表达。作为亚单位疫苗递送的所有抗原，尤其是P42和P95，以及pcDNA3/P46 DNA疫苗能够引发强烈的免疫反应。这些疫苗可诱导细胞免疫反应，并产生能够与天然猪肺炎支原体蛋白反应的抗体。由于诱导了细胞和体液免疫反应，因此P42和P95是重组亚单位疫苗的有希望的候选者，而P46是针对PEP的DNA疫苗的有希望的候选者。

BACKGROUND & AIMS: :Vulvovaginitis is the most frequent gynecologic pathology among prepubertal females. An infectious cause is found in 30% of cases and is highly associated with the presence of vaginal discharge upon examination. Neisseria gonorrhoeae may be one of the causative agents. Since N. gonorrhoeae is a common sexually transmitted disease, sexual abuse should be considered in the pediatric setting. We report the case of a 5-year-old girl with N. gonorrhoeae vulvovaginitis. Her previous history, multiple interviews with the patient and her parents, and clinical examination showed no evidence or signs of sexual abuse. Both parents presented gonorrhea, urethritis for the father and vaginitis for the mother. The discrepancy between pediatric evaluation and the presence of a bacterium associated with sexually transmitted disease led us to consider other means of contamination. Previous studies have shown that other routes of transmission are possible but are often neglected. Hence, contamination can be transmitted by the hands or mostly through passive means (towels, rectal thermometer, etc.). Many epidemics have been noted in group settings with young girls with no evidence of sexual transmission. Therefore, we concluded that this patient's infection was likely an accidental transmission within her family. The acknowledgement of these transmission routes is very important in order to avoid misguided suspicion of sexual abuse and the possible traumatic family and psychosocial consequences.

背景与目标： : 外阴阴道炎是青春期前女性中最常见的妇科病理。在30% 病例中发现了感染原因，并且在检查时与阴道分泌物的存在高度相关。淋球菌可能是病原体之一。由于淋球菌是一种常见的性传播疾病，因此在儿科环境中应考虑性虐待。我们报告了一名5岁女孩患有淋球菌性外阴阴道炎的病例。她以前的病史，对患者及其父母的多次采访以及临床检查都没有发现性虐待的证据或迹象。父母双方都患有淋病，父亲患有尿道炎，母亲患有阴道炎。儿科评估与与性传播疾病相关的细菌之间的差异使我们考虑了其他污染手段。先前的研究表明，其他传播途径是可能的，但通常被忽略。因此，污染可以通过手或主要通过被动手段 (毛巾，直肠温度计等) 传播。在没有性传播证据的年轻女孩的团体环境中，已经发现了许多流行病。因此，我们得出结论，该患者的感染可能是其家庭内部的意外传播。为了避免对性虐待的误导怀疑以及可能造成的家庭和社会心理后果，承认这些传播途径非常重要。

BACKGROUND & AIMS: BACKGROUND:The combinations of methotrexate, vinblastine, Adriamycin, cisplatin (Pharmanell, Athens, Greece) (MVAC) or gemcitabine, cisplatin (GC) represent the standard treatment of advanced urothelial cancer (UC). Dose-dense (DD)-MVAC has achieved longer progression-free survival (PFS) than the conventional MVAC. However, the role of GC intensification has not been studied. We conducted a randomized, phase III study comparing a DD-GC regimen with DD-MVAC in advanced UC. PATIENTS AND METHODS:One hundred and thirty patients were randomly assigned between DD-MVAC: 66 (M 30 mg/m(2), V 3 mg/m(2), A 30 mg/m(2), C 70 mg/m(2) q 2 weeks) and DD-GC 64 (G 2500 mg/m(2), C 70 mg/m(2) q 2 weeks). The median follow-up was 52.1 months (89 events). RESULTS:The median overall survival (OS) and PFS were 19 and 8.5 months for DD-MVAC and 18 and 7.8 months for DD-GC (P = 0.98 and 0.36, respectively). Neutropenic infections were less frequent for DD-GC than for DD-MVAC (0% versus 8%). More patients on DD-GC received at least six cycles of treatment (85% versus 63%, P = 0.011) and the discontinuation rate was lower for DD-GC (3% versus 13%). CONCLUSIONS:Although DD-GC was not superior to DD-MVAC, it was better tolerated. DD-GC could be considered as a reasonable therapeutic option for further study in this patient population. Clinical Trial Number ACTRN12610000845033, www.anzctr.org.au.

背景与目标：

BACKGROUND & AIMS: :With recent advances in synthetic biology, CO2 could be utilized as a carbon feedstock by native or engineered organisms, assuming the availability of electrons. Two key enzymes used in autotrophic CO2 fixation are the CO dehydrogenase (CODH) and acetyl coenzyme A (acetyl-CoA) synthase (ACS), which form a bifunctional heterotetrameric complex. The CODH/ACS complex can reversibly catalyze CO2 to CO, effectively enabling a biological water-gas shift reaction at ambient temperatures and pressures. The CODH/ACS complex is part of the Wood-Ljungdahl pathway (WLP) used by acetogens to fix CO2, and it has been well characterized in native hosts. So far, only a few recombinant CODH/ACS complexes have been expressed in heterologous hosts, none of which demonstrated in vivo CO2 reduction. Here, functional expression of the Clostridium carboxidivorans CODH/ACS complex is demonstrated in the solventogen Clostridium acetobutylicum, which was engineered to express CODH alone or together with the ACS. Both strains exhibited CO2 reduction and CO oxidation activities. The CODH reactions were interrogated using isotopic labeling, thus verifying that CO was a direct product of CO2 reduction, and vice versa. CODH apparently uses a native C. acetobutylicum ferredoxin as an electron carrier for CO2 reduction. Heterologous CODH activity depended on actively growing cells and required the addition of nickel, which is inserted into CODH without the need to express the native Ni insertase protein. Increasing CO concentrations in the gas phase inhibited CODH activity and altered the metabolite profile of the CODH-expressing cells. This work provides the foundation for engineering a complete and functional WLP in nonnative host organisms.IMPORTANCE Functional expression of CO dehydrogenase (CODH) from Clostridium carboxidivorans was demonstrated in C. acetobutylicum, which is natively incapable of CO2 fixation. The expression of CODH, alone or together with the C. carboxidivorans acetyl-CoA synthase (ACS), enabled C. acetobutylicum to catalyze both CO2 reduction and CO oxidation. Importantly, CODH exhibited activity in both the presence and absence of ACS. 13C-tracer studies confirmed that the engineered C. acetobutylicum strains can reduce CO2 to CO and oxidize CO during growth on glucose.

背景与目标： : 随着合成生物学的最新进展，假设电子的可用性，CO2可以被天然或工程生物用作碳原料。自养CO2固定中使用的两种关键酶是CO脱氢酶 (CODH) 和乙酰辅酶a (乙酰辅酶a) 合酶 (ACS)，它们形成了双功能的异四聚体复合物。CODH/ACS复合物可以可逆地将CO2催化为CO，从而在环境温度和压力下有效地实现了生物水煤气变换反应。CODH/ACS复合物是乙酰原菌用来固定CO2的Wood-Ljungdahl途径 (WLP) 的一部分，并且在天然宿主中已得到很好的表征。到目前为止，在异源宿主中仅表达了少数重组CODH/ACS复合物，但均未证明体内CO2还原。在这里，羧基梭菌CODH/ACS复合物的功能性表达在丙酮丁醇梭菌中得到证实，该梭菌经工程设计可单独或与ACS一起表达CODH。两种菌株均表现出CO2还原和CO氧化活性。使用同位素标记对CODH反应进行了询问，从而验证了CO是CO2还原的直接产物，反之亦然。CODH显然使用天然的丙酮丁基铁氧还蛋白作为减少CO2的电子载体。异源CODH活性取决于活跃生长的细胞，需要添加镍，镍被插入CODH中，而不需要表达天然的Ni插入酶蛋白。气相中CO浓度的增加会抑制CODH活性并改变表达CODH的细胞的代谢物谱。这项工作为在非本地宿主生物体中设计完整且功能性的WLP奠定了基础。重要的是，来自碳衣梭菌的CO脱氢酶 (CODH) 的功能表达在丙酮丁基梭菌中得到证明，该菌本身无法固定CO2。CODH单独或与C. carboxidivorans乙酰辅酶a合酶 (ACS) 一起表达，使C.Acetutylicum能够催化CO2还原和CO氧化。重要的是，CODH在存在和不存在ACS时均表现出活性。13c-示踪剂研究证实，工程改造的丙酮丁醇C菌株可以将CO2还原为CO，并在葡萄糖上生长过程中氧化CO。