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1.
Am J Sports Med ; 52(1): 242-257, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-38164688

RESUMO

Orthobiologics are rapidly growing in use given their potential to augment healing for multiple musculoskeletal conditions. Orthobiologics consist of a variety of treatments including platelet-rich plasma and stem cells that provide conceptual appeal in providing local delivery of growth factors and inflammation modulation. The lack of standardization in nomenclature and applications within the literature has led to a paucity of high-quality evidence to support their frequent use. The purpose of this review was to describe the current landscape of orthobiologics and the most recent evidence regarding their use.


Assuntos
Doenças Musculoesqueléticas , Plasma Rico em Plaquetas , Humanos , Doenças Musculoesqueléticas/terapia , Peptídeos e Proteínas de Sinalização Intercelular/uso terapêutico
2.
BMC Med Inform Decis Mak ; 23(1): 196, 2023 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-37770866

RESUMO

BACKGROUND: Fraud, Waste, and Abuse (FWA) in medical claims have a negative impact on the quality and cost of healthcare. A major component of FWA in claims is procedure code overutilization, where one or more prescribed procedures may not be relevant to a given diagnosis and patient profile, resulting in unnecessary and unwarranted treatments and medical payments. This study aims to identify such unwarranted procedures from millions of healthcare claims. In the absence of labeled examples of unwarranted procedures, the study focused on the application of unsupervised machine learning techniques. METHODS: Experiments were conducted with deep autoencoders to find claims containing anomalous procedure codes indicative of FWA, and were compared against a baseline density-based clustering model. Diagnoses, procedures, and demographic data associated with healthcare claims were used as features for the models. A dataset of one hundred thousand claims sampled from a larger claims database is used to initially train and tune the models, followed by experimentations on a dataset with thirty-three million claims. Experimental results show that the autoencoder model, when trained with a novel feature-weighted loss function, outperforms the density-based clustering approach in finding potential outlier procedure codes. RESULTS: Given the unsupervised nature of our experiments, model performance was evaluated using a synthetic outlier test dataset, and a manually annotated outlier test dataset. Precision, recall and F1-scores on the synthetic outlier test dataset for the autoencoder model trained on one hundred thousand claims were 0.87, 1.0 and 0.93, respectively, while the results for these metrics on the manually annotated outlier test dataset were 0.36, 0.86 and 0.51, respectively. The model performance on the manually annotated outlier test dataset improved further when trained on the larger thirty-three million claims dataset with precision, recall and F1-scores of 0.48, 0.90 and 0.63, respectively. CONCLUSIONS: This study demonstrates the feasibility of leveraging unsupervised, deep-learning methods to identify potential procedure overutilization from healthcare claims.


Assuntos
Aprendizado Profundo , Humanos , Aprendizado de Máquina não Supervisionado , Atenção à Saúde , Bases de Dados Factuais , Fraude
3.
Sci Rep ; 13(1): 10479, 2023 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-37380704

RESUMO

Hospital readmissions rate is reportedly high and has caused huge financial burden on health care systems in many countries. It is viewed as an important indicator of health care providers' quality of care. We examine the use of machine learning-based survival analysis to assess quality of care risk in hospital readmissions. This study applies various survival models to explore the risk of hospital readmissions given patient demographics and their respective hospital discharges extracted from a health care claims dataset. We explore advanced feature representation techniques such as BioBERT and Node2Vec to encode high-dimensional diagnosis code features. To our knowledge, this study is the first to apply deep-learning based survival-analysis models for predicting hospital readmission risk agnostic of specific medical conditions and a fixed window for readmission. We found that modeling the time from discharge date to readmission date as a Weibull distribution as in the SparseDeepWeiSurv model yields the best discriminative power and calibration. In addition, embedding representations of the diagnosis codes do not contribute to improvement in model performance. We find dependency of each model's performance on the time point at which it is evaluated. This time dependency of the models' performance on the health care claims data may necessitate a different choice of model in quality of care issue detection at different points in time. We show the effectiveness of deep-learning based survival-analysis models in estimating the quality of care risk in hospital readmissions.


Assuntos
Instalações de Saúde , Readmissão do Paciente , Humanos , Calibragem , Pessoal de Saúde , Qualidade da Assistência à Saúde
4.
J Am Acad Orthop Surg ; 31(21): e920-e929, 2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37364250

RESUMO

Revision anterior cruciate ligament (ACL) reconstruction in the skeletally immature patient is a challenging procedure for pediatric patients with recurrent instability after primary ACL reconstruction. The pediatric population presents unique technical challenges and complications secondary to open physes compared with the adult population. Complications can include growth disturbances, recurrent graft failure, instability, and secondary chondral and/or meniscal injury. Moreover, identifying the etiology of graft failure is critical for a successful revision. Patients should undergo a complete history and physical examination with a focus on patient physiologic age, physeal status, mechanical axis, tibial slope, collagen status, injury mechanism, concomitant injuries, and previous surgical procedures. The surgeon must be adept at reconstruction with various grafts as well as socket or tunnel preparation and fixation, including over-the-top, all-epiphyseal, transphyseal, extra-articular augmentation, and staging approaches. Reported rates of return to sport are lower than those of primary reconstruction, with higher rates of cartilage and meniscal degeneration. Future research should focus on optimizing surgical outcomes and graft survivorship after primary ACL reconstruction with minimized trauma to the physis.

5.
J Bone Joint Surg Am ; 105(13): 1026-1035, 2023 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-37205735

RESUMO

➤ Clinicians should be careful to assess for associated injuries including anterolateral complex and medial meniscal ramp lesions or lateral meniscal posterior root tears.➤ Consideration of lateral extra-articular augmentation should be given for patients with >12° of posterior tibial slope.➤ Patients with preoperative knee hyperextension (>5°) or other nonmodifiable risk factors, including high-risk osseous geometry, may benefit from a concomitant anterolateral augmentation procedure to improve rotational stability.➤ Meniscal lesions should be addressed at the time of anterior cruciate ligament reconstruction with meniscal root or ramp repair.


Assuntos
Lesões do Ligamento Cruzado Anterior , Traumatismos do Joelho , Lesões do Menisco Tibial , Humanos , Lesões do Ligamento Cruzado Anterior/cirurgia , Lesões do Menisco Tibial/cirurgia , Meniscos Tibiais/cirurgia , Tíbia/cirurgia , Traumatismos do Joelho/cirurgia , Articulação do Joelho/cirurgia
6.
Instr Course Lect ; 72: 445-459, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36534872

RESUMO

A first-time shoulder dislocation is a challenging topic that requires consideration of anatomic and patient-specific factors. Initial management is predicated on determining functional demands, activity level, and expectations of the patient, in addition to assessing the risk of recurrent instability. When considering surgical indications, it is imperative to understand the biomechanical implications of injury to the glenohumeral joint complex and how specific surgical procedures can restore stability. It is important to provide an overview of the current treatment algorithm for management of first-time shoulder dislocation, with a special focus on diagnosis and intervention in the young athlete.


Assuntos
Instabilidade Articular , Luxação do Ombro , Articulação do Ombro , Humanos , Ombro , Luxação do Ombro/cirurgia , Articulação do Ombro/cirurgia , Instabilidade Articular/cirurgia
7.
J Bone Joint Surg Am ; 104(21): 1886-1894, 2022 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-35984013

RESUMO

BACKGROUND: Prior studies have demonstrated mitochondrial dysfunction in tendinopathy. The objective of this investigation was to explore the potential of SS-31 (elamipretide), a mitochondrial protectant, to improve mitochondrial function and promote tendon healing in a murine supraspinatus tendinopathy model. METHODS: One hundred and twenty-six mice (252 limbs) were divided into 6 groups (42 limbs/group) that received (I) 4 weeks of impingement; (II) 8 weeks of impingement; (III) 8 weeks of impingement including 4 weeks of SS-31 treatment (5 mg/kg/d) starting after 4 weeks of impingement; (IV) 4 weeks of impingement ending with clip removal, followed by harvesting 4 weeks later; and (V) 4 weeks of impingement ending with clip removal, followed by 4 weeks of SS-31 treatment and harvesting; and a control group. Specimens were prepared for biomechanical testing, histological analysis, transmission electron microscopy, measurement of superoxidative dismutase (SOD) activity, and measurement of gene expression. RESULTS: Failure force decreased after impingement, compared with the intact tendon, and the decrease was partially reversed after clip removal, SS-31 treatment, and the 2 treatments combined. A similar pattern was observed for stiffness. Histological analysis demonstrated higher modified Bonar scores in the impingement groups; however, the changes in tendon morphology were partially reversed following all treatments, especially the combined treatment. Decreased mitochondrial number and altered organization and density of cristae were observed in the impingement groups. Mitochondrial structure and number became more normal, with improvement in morphology of the cristae, after clip removal and/or SS-31 treatment. SOD activity decreased after impingement, compared with the control group, then increased significantly again after treatment, especially in the combined treatment group. Mitochondria-related gene expression decreased in the impingement groups and increased again after treatment. CONCLUSIONS: The mitochondrial protectant SS-31 improved mitochondrial function, promoting tendon healing, especially when combined with removal of subacromial impingement. CLINICAL RELEVANCE: Improving mitochondrial function with agents such as SS-31 may represent an effective treatment to promote healing in the setting of supraspinatus tendinopathy.


Assuntos
Oligopeptídeos , Síndrome de Colisão do Ombro , Tendinopatia , Animais , Camundongos , Mitocôndrias/patologia , Manguito Rotador/patologia , Síndrome de Colisão do Ombro/patologia , Superóxido Dismutase/metabolismo , Tendinopatia/tratamento farmacológico , Tendinopatia/patologia , Oligopeptídeos/farmacologia
8.
J Arthroplasty ; 37(7S): S647-S652, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35210150

RESUMO

BACKGROUND: Numerous studies have examined the use of topical and irrigation-related adjuvants to decrease the risk of periprosthetic joint infection (PJI) after total hip arthroplasty. Many issues related to their use remain to be investigated. These include cost, antibiotic stewardship, bactericidal effect on planktonic bacteria, host cytotoxicity, necessity to irrigate/dilute potentially cytotoxic agents after their application, and impact on biofilm. METHODS: Bacterial strains of microorganisms were grown in optimal medium. After the growth phase, the organisms were exposed to the novel irrigation solution (XPerience) or phosphate buffer solution (PBS) for 5 minutes before a neutralizing broth was added. The colony-forming units per milliliter and the log reduction in colony-forming units in the treated sample vs the control were then determined. Subsequently, biofilms of microorganisms were grown on hydroxyapatite-coated glass slides. Each slide was then exposed to irrigation solutions for various contact times. Biofilm quantification was performed and the log10 density of each organism was obtained. RESULTS: In vitro testing of the irrigant demonstrated 6-log reductions in planktonic bacteria in 5 minutes, and 4-log to 8-log reductions in biofilms. Laboratory tissue testing has demonstrated minimal cytotoxic effects to host tissue allowing for solution to remain in contact with the host without need for subsequent irrigation, creating a barrier to biofilm for up to 5 hours after its application. CONCLUSION: This novel irrigant demonstrates high efficacy against both planktonic bacteria and bacterial biofilms in laboratory testing. Large series in vivo data are necessary to further establish its efficacy in reducing primary and recurrent surgical site infections.


Assuntos
Artroplastia de Quadril , Infecções Relacionadas à Prótese , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Bactérias , Biofilmes , Humanos , Plâncton , Infecções Relacionadas à Prótese/microbiologia
9.
Spine (Phila Pa 1976) ; 47(3): E101-E106, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34091562

RESUMO

STUDY DESIGN: Retrospective observational study. OBJECTIVE: The aim of this study was to investigate the spinal cord safety margins for C2 instrumentation. SUMMARY OF BACKGROUND DATA: Intraoperative spinal cord injury during C2 spine surgery is a rare, but potentially life-threatening complication. Preoperative planning for C2 instrumentation mainly focuses on C2 pedicle bony dimensions on CT and the vertebral artery location and few studies have evaluated C2 spinal cord safety margins. METHODS: We measured two distances in C2 bilaterally: C2 pedicle to dura distance (P-D), defined as a transverse line that measured the shortest distance between the medial wall of the C2 pedicle and the dural sac, and C2 pedicle to spinal cord (P-SC), defined as a transverse line that measured the shortest distance between the medial wall of the C2 pedicle and spinal cord. We defined the distances >4 mm as safe for instrumentation. RESULT: A total of 146 patients (mean age 71.2, 50.7% female) were included. The average distances were 5.5 mm for C2 left PD, 5.9 mm for C2 right P-D, 10.1 mm for C2 left P-SC, and 10.6 mm for C2 right P-SC. Twenty-eight (21.4%) patients had C2 P-D distances <4 mm and of those two (7%) patients had distances <2 mm. There were more female patients with C2 P-D distances under 4 mm compared to males. No patient had C2 P-SC distances <4 mm. CONCLUSION: We demonstrated that around 20% of patients had C2 P-D distance <4 mm, but no patient had C2 P-SC distance <4 mm. Since a lateral misplacement can lead to a potentially fatal vertebral artery injury, medial screw trajectory is recommended for C2 pedicle instrumentation with consideration of these safety margins.Level of Evidence: 3.


Assuntos
Parafusos Pediculares , Fusão Vertebral , Parafusos Ósseos , Vértebras Cervicais , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Medula Espinal/diagnóstico por imagem , Fusão Vertebral/efeitos adversos , Artéria Vertebral
10.
J Shoulder Elbow Surg ; 30(5): 977-985, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33220412

RESUMO

Unique biologic and biomechanical aspects of the female body make women more prone to certain orthopedic injuries. Sex differences are well understood with regard to certain orthopedic pathologies such as anterior cruciate ligament injury, hallux valgus, carpal tunnel, and carpometacarpal joint arthritis; however, sex differences are less commonly discussed with regard to shoulder and elbow pathology. The purpose of this review is to elucidate sex differences specific to sports-related shoulder and elbow injuries in the female athlete population.


Assuntos
Traumatismos em Atletas , Lesões no Cotovelo , Atletas , Traumatismos em Atletas/epidemiologia , Fenômenos Biomecânicos , Feminino , Humanos , Masculino , Ombro
11.
Nicotine Tob Res ; 21(9): 1220-1227, 2019 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-29912406

RESUMO

BACKGROUND: Smoking is a leading cause of numerous human disorders including pulmonary disease, cardiovascular disease, and cancer. Disease development is primarily caused by exposure to cigarette smoke constituents, many of which are known toxicants. Switching smokers to modified risk tobacco products (MRTPs) has been suggested as a potential means to reduce the risks of tobacco use, by reducing such exposure. METHODS: This randomized, controlled study investigated whether biomarkers of toxicant exposure (BoE) were reduced when smokers switched from smoking combustible cigarettes to using a novel (glo™/THP1.0) or in-market comparator (iQOS/THS) tobacco heating product (THP). One hundred eighty Japanese smokers smoked combustible cigarettes during a 2-day baseline period, followed by randomization to either continue smoking cigarettes, switch to using mentholated or non-mentholated variants of glo™, switch to using a non-mentholated variant of iQOS, or quit nicotine and tobacco product use completely for 5 days. Baseline and post-randomization 24-h urine samples were collected for BoE analysis. Carbon monoxide was measured daily in exhaled breath (eCO). RESULTS: On day 5 after switching, urinary BoE (excluding for nicotine) and eCO levels were significantly (p < .05) reduced by medians between 20.9% and 92.1% compared with baseline in all groups either using glo™ or iQOS or quitting tobacco use. Between-group comparisons revealed that the reductions in the glo™ groups were similar (p > .05) to quitting in many cases. CONCLUSIONS: glo™ or iQOS use for 5 days reduced exposure to smoke toxicants in a manner comparable to quitting tobacco use. THPs are reduced exposure tobacco products with the potential to be MRTPs. IMPLICATIONS: This clinical study demonstrates that when smokers switched from smoking combustible cigarettes to using tobacco heating products their exposure to smoke toxicants was significantly decreased. In many cases, this was to the same extent as that seen when they quit smoking completely. This may indicate that these products have the potential to be reduced exposure and/or reduced risk tobacco products when used by smokers whose cigarette consumption is displaced completely. CLINICAL TRIAL REGISTRATIONS: ISRCTN14301360 and UMIN000024988.


Assuntos
Fumar Cigarros/epidemiologia , Fumar Cigarros/urina , Sistemas Eletrônicos de Liberação de Nicotina , Nicotina/urina , Produtos do Tabaco/análise , Adulto , Biomarcadores/urina , Feminino , Calefação/efeitos adversos , Humanos , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Abandono do Hábito de Fumar , Produtos do Tabaco/efeitos adversos
12.
BMC Public Health ; 17(1): 673, 2017 08 22.
Artigo em Inglês | MEDLINE | ID: mdl-28830420

RESUMO

BACKGROUND: Smoking is a leading cause of numerous human disorders including lung cancer, chronic obstructive pulmonary disease, and atherosclerotic cardiovascular disease. The development of modified risk tobacco products (MRTPs) has been suggested as a possible way to reduce the risks of tobacco smoking by reducing exposure to cigarette smoke toxicants. This study is designed to investigate whether biomarkers of such exposure are reduced when smokers switch from smoking commercial cigarettes to using either a novel or a commercially-available tobacco heating product (THP). DESIGN AND METHODS: This study will assess biomarkers of exposure in current smokers who either remain smoking, switch to THP use, or quit all tobacco use completely, for 5 days. The study is an in-clinic (confinement) two-centre, randomised controlled clinical study with a forced-switching design. Subjects of either gender will be aged 23-55 years (minimum legal smoking age plus 3 years), of Japanese origin and with a verified smoking status (assessed by exhaled breath carbon monoxide and urinary cotinine levels). Subjects will have a usual brand cigarette within the International Organisation for Standardisation (ISO) tar band of 6-8 mg and will be judged to be healthy by medical history, physical examination, vital signs, electrocardiography (ECG), clinical biochemistry and lung function tests. The primary objective of this study is to assess changes within groups in selected biomarkers of exposure (BoE) and of biological effect (BoBE) after a forced switch from a commercial control cigarette to either a menthol or a non-menthol THP. Secondary objectives are to assess between-group differences, to determine nicotine pharmacokinetics for cigarettes and THPs, to assess subject's satisfaction with the study products, and to monitor additional endpoints related to safety and product use. DISCUSSION: Data from this study will advance our scientific understanding of the changes in exposure to cigarette smoke toxicants in smokers who switch to using a THP. TRIAL REGISTRATIONS: UMIN000024988 (25th November 2016); ISRCTN14301360 (14th December 2016).


Assuntos
Biomarcadores/análise , Fumar , Produtos do Tabaco/estatística & dados numéricos , Adulto , Biomarcadores/urina , Testes Respiratórios , Feminino , Calefação , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Fumar/urina , Adulto Jovem
13.
Drug Discov Today ; 21(2): 212-6, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26523771

RESUMO

Billions of dollars spent, millions of subject-hours of clinical trial experience and an abundance of archived study-level data, yet why are historical data underutilized? We propose that historical data can be aggregated to provide safety, background incidence rate and context to improve the evaluation of new medicinal products. Here, we describe the development and application of the eControls database, which is derived from the control arms of studies of licensed products, and discuss the challenges and potential solutions to the proper application of historical data to help interpret product safety.


Assuntos
Bases de Dados Factuais , Estudo Historicamente Controlado , Segurança do Paciente , Ensaios Clínicos como Assunto , Humanos
14.
J Am Med Inform Assoc ; 20(e1): e162-8, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23449762

RESUMO

BACKGROUND: Ethical concerns about randomly assigning patients to suboptimal or placebo arms and the paucity of willing participants for randomization into control and experimental groups have renewed focus on the use of historical controls in clinical trials. Although databases of historical controls have been advocated, no published reports have described the technical and informatics issues involved in their creation. OBJECTIVE: To create a historical controls database by leveraging internal clinical trial data at Pfizer, focusing on patients who received only placebo in randomized controlled trials. METHODS: We transformed disparate clinical data sources by indexing, developing, and integrating clinical data within internal databases and archives. We focused primarily on trials mapped into a consistent standard and trials in the pain therapeutic area as a pilot. RESULTS: Of the more than 20,000 internal Pfizer clinical trials, 2404 completed placebo controlled studies with a parallel design were identified. Due to challenges with informed consent and data standards used in older clinical trials, studies completed before 2000 were excluded, yielding 1134 studies from which placebo subjects and associated clinical data were extracted. CONCLUSIONS: It is technically feasible to pool portions of placebo populations through a stratification and segmentation approach for a historical placebo group database. A sufficiently large placebo controls database would enable previous distribution calculations on representative populations to supplement, not eliminate, the placebo arm of future clinical trials. Creation of an industry-wide placebo controls database, utilizing a universal standard, beyond the borders of Pfizer would add significant efficiencies to the clinical trial and drug development process.


Assuntos
Grupos Controle , Bases de Dados como Assunto , Ensaios Clínicos Controlados Aleatórios como Assunto/métodos , Indexação e Redação de Resumos , Humanos , Placebos/uso terapêutico , Projetos de Pesquisa
15.
Org Lett ; 13(9): 2376-9, 2011 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-21486077

RESUMO

The total synthesis of (-)-swainsonine from 2,3-O-isopropylidene-D-erythrose in 12 steps and an overall yield of 28% is reported. The pivotal transformation in our route to this indolizidine alkaloid is the formation of the pyrrolidine ring and C-8a/8 stereodiad through the diastereoselective, bis-cyclofunctionalization of an γ,δ-unsaturated O-alkyl hydroxamate. This transformation is believed to proceed via the intramolecular capture of an N-acyl-N-alkoxyaziridinium ion generated by the diastereoselective addition of a singlet acylnitrenium ion to the pendant alkene.


Assuntos
Alcenos/química , Compostos de Nitrogênio/química , Swainsonina/síntese química , Cátions/química , Ciclização , Estrutura Molecular , Oxirredução
16.
Org Lett ; 12(22): 5330-3, 2010 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-20964285

RESUMO

The asymmetric total synthesis of the α-glucosidase inhibitor (+)-castanospermine is reported. The central theme in our approach to this polyhydroxylated alkaloid is the simultaneous generation of the piperidine ring and the C-1/8a erythro stereodiad through the diastereoselective, oxamidation of an unsaturated O-alkyl hydroxamate. This process is believed to proceed sequentially via singlet acylnitrenium and aziridinium ion intermediates.


Assuntos
Alcaloides/síntese química , Inibidores de Glicosídeo Hidrolases , Indolizinas/síntese química , Alcaloides/química , Alcaloides/farmacologia , Catálise , Ciclização , Indolizinas/química , Indolizinas/farmacologia , Íons , Estrutura Molecular , Estereoisomerismo
17.
J Am Chem Soc ; 132(4): 1188-9, 2010 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-19788297

RESUMO

The development of a versatile method for the preparation of five- to eight-membered hydroxy lactams that involves the iodine(III)-mediated oxamidation of unsaturated O-alkyl hydroxamates is described. This transformation, which is believed to proceed through the intermediacy of singlet nitrenium and bicyclic N-acyl-N-alkoxyaziridinium ions, is both stereospecific and highly regioselective in most of the 22 cases examined.


Assuntos
Ácidos Hidroxâmicos/química , Lactamas/química , Ciclização , Estrutura Molecular
18.
J Am Chem Soc ; 131(17): 6062-3, 2009 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-19361223

RESUMO

The enantioselective total synthesis of the potent alpha-glucosidase inhibitors schulzeine A, B, and C and a revision of the proposed C20' configuration of schulzeine A are reported. The central feature of our convergent route to this family of novel marine natural products is the preparation of the common benzo[a]quinolizidine subunit through a substrate-controlled, diastereoselective Pictet-Spengler cyclocondensation.


Assuntos
Inibidores Enzimáticos/síntese química , Inibidores de Glicosídeo Hidrolases , Compostos Heterocíclicos com 3 Anéis/síntese química , Lactamas/síntese química , Quinolizidinas/síntese química , Ésteres do Ácido Sulfúrico/síntese química , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Compostos Heterocíclicos com 3 Anéis/química , Compostos Heterocíclicos com 3 Anéis/farmacologia , Lactamas/química , Lactamas/farmacologia , Estrutura Molecular , Quinolizidinas/química , Quinolizidinas/farmacologia , Estereoisomerismo , Ésteres do Ácido Sulfúrico/química , Ésteres do Ácido Sulfúrico/farmacologia
19.
Chem Commun (Camb) ; (40): 5106-8, 2005 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-16220186

RESUMO

A synthetic route to the neurotrophic agent (+)-lactacystin has been developed utilizing a base-promoted intramolecular alkylidenecarbene C-H insertion as the key transformation.


Assuntos
Acetilcisteína/análogos & derivados , Acetilcisteína/síntese química , Acetilcisteína/química , Alquilação , Hidrocarbonetos/química , Metano/análogos & derivados , Metano/química , Estrutura Molecular , Pirróis/química
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