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1.
J Infect Chemother ; 2024 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-38336170

RESUMO

The present case reports a bacteremia due to Lachnoanaerobaculum umeaense (a Gram-positive, filamentous, rod-shaped, anaerobic, spore-forming bacillus present in the human oral microbiota) in a patient treated for acute myeloid leukemia. After failed identification by MALDI-TOF, identification was done by sequencing of 16s rRNA. The patient was successfully treated with Amoxicillin-clavulanic acid and ciprofloxacin for seven days. Comparison of V1-V3 regions of the bacterial 16S rRNA gene gene with published sequences failed to classify the strain as pathogenic or non-pathogenic based on this phylogenetic classification alone. Although Lachnoanaerobaculum gingivalis are known to be associated with bacteremia in patients with acute myeloid leukemia, this clinical case of infection by L. umeaense argues for further studies that will lead to more efficient classification of the infection by these microorganisms.

2.
J Clin Microbiol ; 58(4)2020 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-31996442

RESUMO

The noninvasive detection of Helicobacter pylori and its resistance to clarithromycin could revolutionize the management of H. pylori-infected patients by tailoring eradication treatment without any need for endoscopy when histology is not necessary. Several real-time PCR tests performed on stools have been proposed, but their performances were either poor or they were tested on too few patients to be properly evaluated. We conducted a prospective, multicenter study including 1,200 adult patients who were addressed for gastroduodenal endoscopy with gastric biopsies and who were naive for eradication treatment in order to evaluate the performance of the Amplidiag H. pylori+ClariR assay recently developed by Mobidiag (Espoo, Finland). The results of the Amplidiag H. pylori+ClariR assay performed on DNA from stools (automatic extraction with the EasyMag system [bioMérieux]) were compared with those of culture/Etest and quadruplex real-time PCRs performed on two gastric biopsy samples (from the antrum and corpus) to detect the H. pyloriglmM gene and mutations in the 23S rRNA genes conferring clarithromycin resistance. The sensitivity and specificity of the detection of H. pylori were 96.3% (95% confidence interval [CI], 92 to 98%) and 98.7% (95% CI, 97 to 99%), respectively. The positive and negative predictive values were evaluated to be 92.2% (95% CI, 92 to 98%) and 99.3% (95% CI, 98 to 99%), respectively. In this cohort, 160 patients (14.7%) were found to be infected (positive by culture and/or PCR). The sensitivity and specificity for detecting resistance to clarithromycin were 100% (95% CI, 88 to 100%) and 98.4% (95% CI, 94 to 99%), respectively.


Assuntos
Infecções por Helicobacter , Helicobacter pylori , Adulto , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Biópsia , Claritromicina/farmacologia , Farmacorresistência Bacteriana , Finlândia , Infecções por Helicobacter/diagnóstico , Infecções por Helicobacter/tratamento farmacológico , Helicobacter pylori/genética , Humanos , Testes de Sensibilidade Microbiana , Estudos Prospectivos , Reação em Cadeia da Polimerase em Tempo Real
3.
Anaerobe ; 64: 102244, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32712374

RESUMO

Initially isolated from the alimentary canal of a Japanese corbicula clam, Oscillibacter valericigenes is a Gram-negative rod, of which culture remains very difficult. Herein we present the first case of bacteremia due to Oscillibacter valericigenes, in humans. A 55-year-old man was hospitalized for clinical management of multiple neglected leg wounds (colonized with maggots) that had occurred during a motorcycle accident. Following radiological confirmation of the bone infection, a transfemoral amputation was performed to limit the risk of extended infection. During hospitalization, before the amputation, the patient experienced fever, biological inflammation justifying the sampling of multiple blood cultures. Anaerobic blood culture was positive after 34 hours, without identification by routine procedure (MALDI-TOF), justifying identification by 16S DNA sequencing. In the absence of possible subculture, antibiotic sensitivity testing could not be performed. A pre-emptive treatment by piperacillin-tazobactam was introduced for 14 days. The evolution was good, except for a local disunion. Complete phylogenic analysis of the clinical strain showed that it significantly differed from the reference strain, which is distantly related to the Clostridia cluster IV. Due to the culture conditions and specialized identification method by sequencing, prevalence of O. valericigenes may be underestimated. Optimization of blood culture procedures and utilization of 16S rRNA gene sequencing are tools needed for identification of rare pathogens that could help to optimize clinical management of infected patients.


Assuntos
Bacteriemia/diagnóstico , Bacteriemia/terapia , Clostridiales/classificação , Clostridiales/isolamento & purificação , Combinação Piperacilina e Tazobactam/uso terapêutico , Amputação Cirúrgica , Antibacterianos/uso terapêutico , Técnicas de Tipagem Bacteriana , DNA Bacteriano/genética , Hospitalização , Humanos , Perna (Membro)/cirurgia , Masculino , Pessoa de Meia-Idade , Filogenia , RNA Ribossômico 16S/genética
4.
Antibiotics (Basel) ; 12(3)2023 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-36978395

RESUMO

Corynebacterium gottingense is a Gram-positive bacillus that has not been reported as pathogenic in pediatric patients. Herein, a case of catheter-associated bloodstream infection by C. gottingense in a 13-year-old immunocompromised child with febrile neutropenia induced for osteosarcoma is reported. The species was identified by Sanger sequencing of the 16s rRNA sequence of the bacterial strain and was compared phylogenetically with published sequences. As suggested in the literature, the presented strain was multi-susceptible, particularly to amoxicillin. The patient was treated with piperacillin/tazobactam for seven days in the context of a urinary co-infection, resulting in resolution of fever within 48 h and then relaunched with oral amoxicillin for 3 days (for a total of 10 days of antibiotic therapy). Phylogenetic analyses based on 16S rDNA demonstrated the complexity of the genus Corynebacterium spp. but failed to demonstrate a direct benefit in predicting clinical outcome based on this single information.

5.
Antibiotics (Basel) ; 12(9)2023 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-37760766

RESUMO

Oligella ureolytica is a Gram-negative bacillus, a member of the Alcaligenaceae family, that had never previously been reported as lethal. Herein, a case of fatal infection caused by Oligella ureolytica in an elderly woman with suspected bladder cancer is reported. The species identification was confirmed through Sanger sequencing of the bacterial 16S rRNA sequence and compared to published sequences for phylogenetic analysis. Initial antibiotic therapy with ceftriaxone and oxacillin was initiated but had to be switched due to resistance. Cefepime in combination with metronidazole was administered, unfortunately failing to prevent the patient's death. Further studies are needed to explore additional factors influencing clinical outcomes in Oligella ureolytica infections.

6.
Microorganisms ; 9(9)2021 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-34576781

RESUMO

Escherichia coli is responsible for diseases of varying severity. The "K" antigen designates the capsular polysaccharides on the bacterial surface, which are mostly similar to those of highly pathogenic bacteria. The K1 antigen is often found in pathogenic E. coli. Aim: While the published studies on the AST profile of K1-positive E. coli have focused on pregnant women or newborns, this study aimed to characterize the AST profile of K1-positive E. coli independently of the clinical sample of isolation. Over a 4-week-long period, all patients hospitalized/consulting at the Poitiers University Hospital presenting a determined AST on E. coli were prospectively included to define their K1-status (Pastorex Meningitis) and to collect the clinical (age/sex) or biological metadata (AST/MIC). Among the 296 included samples, no differential representation was observed between K1 results regarding sample nature. K1-negative results were associated with multiple antibiotic-resistance (12.3% vs. 33.0%; p < 0.01). AST phenotypes differed between these groups, with a higher proportion of K1-negativity among resistant strains, especially on ß-lactams (ureidopenicillin, 25.8% vs. 14.9%; and ampicillin/inhibitor, 50.0% vs. 26.8%; p < 0.05) or quinolone (19.8% vs. 7.0%) and sulfamethoxazole-trimethoprim (30.2% vs. 12.3%) (p < 0.01). This study analyzed E. coli ASTs in clinical samples of all types, regarding their K1-antigen status.

7.
Semin Radiat Oncol ; 27(1): 50-66, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27986212

RESUMO

A total of 3 randomized clinical trials have demonstrated a significant clinical benefit with adjuvant radiation in patients with high-risk prostate cancer after radical prostatectomy, with each showing improved biochemical control outcomes, and one trial (SWOG 8794) also demonstrating increased overall survival. How broadly these results have informed clinical practice has evolved over time, given the widespread availability of ultrasensitive prostate-specific antigen level testing and increased awareness that the high-risk patients are not a uniform cohort. In this review, we discuss the evidence from published and ongoing trials as well as current controversies, focusing on unanswered questions such as when postoperative radiation should be offered and whether the inclusion of androgen-deprivation therapy improves clinical outcomes. The emerging interest in genomic prediction tools and the enhanced sensitivity of novel imaging modalities should offer strategies to improve patient selection, which would help to identify men who may benefit from postoperative radiation while avoiding unnecessary treatment and toxicities in other men.


Assuntos
Prostatectomia , Neoplasias da Próstata/radioterapia , Neoplasias da Próstata/cirurgia , Humanos , Masculino , Antígeno Prostático Específico/sangue , Neoplasias da Próstata/sangue , Radioterapia Adjuvante , Ensaios Clínicos Controlados Aleatórios como Assunto
8.
Brachytherapy ; 15(1): 65-70, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26521660

RESUMO

BACKGROUND: Cervical cancer patients are faced with an enormous amount of medical information in a complex oncology field with sophisticated treatments including brachytherapy. We investigated the use of enhanced vs. standard brachytherapy-specific educational materials on patient-reported satisfaction during the informed consent process for intracavitary high-dose-rate brachytherapy. METHODS AND MATERIALS: A single-institution, prospective, randomized trial was performed to study patient-reported satisfaction with novel educational materials for high-dose-rate brachytherapy in women undergoing definitive radiation for cervical cancer. RESULTS: Fourteen women receiving informed consent with a customized educational booklet were randomized between no further intervention and take-home educational materials. The weighted average for 10 of 11 survey questions was higher in the intervention arm but ranged between 4 (agree) and 5 (strongly agree) for all questions in both arms. The mean weighted patient satisfaction scores ± standard deviations in the control arm and the intervention arms were 54.3 ± 6.4 and 57.5 ± 2.7, respectively (p = 0.26). CONCLUSIONS: Knowledge acquisition is presumed to be part of the coping process for women facing increased stress during a cancer diagnosis. A brachytherapy-specific, visual, patient-educational booklet and take-home materials used to supplement the informed consent process for high-dose-rate brachytherapy resulted in high levels of patient-reported satisfaction among women treated with cervical cancer.


Assuntos
Braquiterapia , Educação de Pacientes como Assunto/métodos , Satisfação do Paciente , Neoplasias do Colo do Útero/radioterapia , Adulto , Idoso , Braquiterapia/métodos , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Pessoa de Meia-Idade , Estudos Prospectivos , Dosagem Radioterapêutica , Inquéritos e Questionários
9.
Brachytherapy ; 15(5): 578-83, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27476646

RESUMO

PURPOSE: To investigate process efficiency, we present a prospective investigation of the treatment planning phase of image-guided brachytherapy (BT) for cervical cancer using a specific checklist. METHODS AND MATERIALS: From October 2012 to January 2014, 76 BT procedures were consecutively performed. Prospective data on the CT-based treatment planning process was collected using a specific checklist which details the following steps: (1) dosimetry planning, (2) physician review start, (3) physician review time, (4) dosimetry processing, (5) physics review start, (6) physics review, and (7) procedural pause. Variables examined included the use of a pre-BT MRI, clinic duty conflicts, resident teaching, and the use of specific BT planners. Analysis was performed using descriptive statistics, t-test, and analysis of variance. RESULTS: Seventy-five prospectively gathered checklists comprised this analysis. The mean time for treatment planning was 95 minutes (med 94, std 18). The mean intervals in the above steps were (1) = 42, (2) = 5, (3) = 19, (4) = 10, (5) = 6, (6) = 13, and (7) = 26 minutes. There was no statistical difference in patients who had a pre-BT MRI. Resident teaching did not influence time, p = 0.17. Treatment planning time was decreased with a specific planner, p = 0.0015. CONCLUSIONS: A skillful team approach is required for treatment planning efficiency in image-guided BT. We have found that the specific BT planners can have a significant effect on the overall planning efficiency. We continue to examine clinical and workflow-related factors that will enhance our safety and workflow process with BT.


Assuntos
Braquiterapia , Eficiência Organizacional , Radioterapia Guiada por Imagem , Neoplasias do Colo do Útero/radioterapia , Fluxo de Trabalho , Adulto , Idoso , Lista de Checagem , Feminino , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Avaliação de Processos em Cuidados de Saúde , Estudos Prospectivos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Estudos de Tempo e Movimento , Tomografia Computadorizada por Raios X
10.
Anticancer Res ; 36(6): 3013-7, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27272819

RESUMO

AIM: To evaluate Radiation Therapy Oncology Group planning target volume margins of 7-10 mm for radiation therapy in anorectal cancer using prone belly-board positioning without image guidance. PATIENTS AND METHODS: 375 kV cone beam computed tomography image-guided radiotherapy (IGRT) images from 20 patients treated for anorectal cancer were retrospectively analyzed for setup shifts. We calculated the total translational shift for each patient and the frequency with which setup shifts exceeded 7 mm and 10 mm. RESULTS: A total of 42.7% of treatments required shifts >7 mm and 20.8% >10 mm. The mean translational shift was 7.1 mm. 70% of patients experienced shifts ≥7 mm in 20% or more of their treatments and 25% of ≥10 mm in 20% or more of their treatments; 15% experienced shifts ≥10 mm in over half of their treatments. van Herk calculations suggest margins of 12.8 mm are necessary for accuracy without IGRT. CONCLUSION: IGRT using a prone belly board and 7-10 mm margins requires daily image-guidance to prevent planning target volume misses and ensure optimal dose delivery.


Assuntos
Tomografia Computadorizada de Feixe Cônico/métodos , Posicionamento do Paciente , Radioterapia Guiada por Imagem/métodos , Neoplasias Retais/radioterapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Índice de Massa Corporal , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
11.
Laryngoscope ; 124(8): 1807-12, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24338219

RESUMO

OBJECTIVES/HYPOTHESIS: To examine functional and quality-of-life outcomes for patients treated by reirradiation to the head and neck for recurrent or new primary cancers. STUDY DESIGN: Retrospective review. METHODS: The University of Washington Quality of Life Instrument (UW-QOL) scores were reviewed with swallow evaluations for 17 patients with biopsy-proven recurrent or new primary squamous cell carcinoma of the head and neck treated with reirradiation who were clinically without evidence of disease at a minimum follow-up of 1 year. All patients had received their initial radiation therapy to a median dose of 66 Gy (range, 60-72 Gy). The median interval between radiation courses was 30 months (range, 6-132 months). The median reirradiation dose was 60 Gy (range, 54-70 Gy). RESULTS: At 1 year after reirradiation, the mean UW-QOL composite score was 67.0 (range, 22.1-83.5), which did not differ significantly from baseline (P = .57). The proportion of patients who rated their global quality of life as "very good" or "outstanding" at 1 year after reirradiation was 35%. The percentage of patients who reported their global quality of life as "good/fair" and "poor/very poor" were 59% and 6%, respectively. CONCLUSIONS: The majority of survivors in this highly selected series were devoid of new impairment after reirradiation and were satisfied with their functional status. Although nearly all patients had side effects from their prior radiation course prior to reirradiation, no patient reported a decline in global quality of life from before reirradiation to 1 year post-treatment.


Assuntos
Carcinoma de Células Escamosas/radioterapia , Neoplasias de Cabeça e Pescoço/radioterapia , Recidiva Local de Neoplasia/radioterapia , Qualidade de Vida , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Retratamento , Estudos Retrospectivos , Resultado do Tratamento
12.
Head Neck ; 36(7): 992-7, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23780718

RESUMO

BACKGROUND: The purpose of this study was to determine the feasibility of nondaily image-guided radiotherapy (RT) strategies with intensity-modulated radiotherapy (IMRT) for head and neck cancer. METHODS: Alignment data was analyzed from 103 consecutive patients treated by IMRT for head and neck cancer who had undergone daily imaging with onboard mega-voltage CT (MVCT), resulting in 3275 images. Geometric setup errors that would have occurred using less-than-daily imaging were hypothetically estimated for 4 temporal less-than-daily image-guided RT protocols. RESULTS: For image-guided RT on the first fraction, weekly image-guided RT, first 5 + weekly image-guided RT, and alternating day image-guided RT, the respective incidences of geometric miss were 50.5%, 33.8%, 30.1%, and 15.7% assuming 3-mm uncertainty margins; and 18.7%, 11.7%, 10.3%, and 4.1% with 5-mm margins. CONCLUSION: Less-than-daily image-guided RT strategies result in a high incidence of potential miss when 3-mm uncertainty margins are utilized. Less-than-daily image-guided RT strategies should incorporate margins of at least 5 mm.


Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Radioterapia Guiada por Imagem/métodos , Radioterapia de Intensidade Modulada , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Fracionamento da Dose de Radiação , Estudos de Viabilidade , Feminino , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Humanos , Masculino , Pessoa de Meia-Idade , Erros de Configuração em Radioterapia , Tomografia Computadorizada por Raios X , Adulto Jovem
13.
Rapid Commun Mass Spectrom ; 19(3): 363-8, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15645500

RESUMO

Acetonitrile chemical ionization tandem mass spectrometry has recently been shown to be a rapid method for the identification of double-bond position and geometry in methyl esters of conjugated linoleic acids (CLAs); however, the structures of intermediate and diagnostic ions and their mechanisms of formation are not known. A mechanism is proposed here in which the m/z 54 ion, (1-methyleneimino)-1-ethenylium (MIE), undergoes nucleophilic attack preferentially by the cis double bond in CLAs with mixed geometry (cis/trans, trans/cis), favoring the observed C--C cleavage vinylic to the trans double bond. The [M+54](+) addition product intermediate is consistent with a heterocyclic six-membered ring resulting from the two-step addition of MIE to the CLA. Experiments with isotopically labeled CLAs and acetonitrile, and from MS/MS/MS experiments, yield data consistent with this proposal. The proposed mechanism is also consistent with known ion-molecule chemistry in smaller compounds, and explains most phenomena associated with MIE-CLA ion chemistry.


Assuntos
Acetonitrilas/química , Ânions/química , Ácidos Linoleicos Conjugados/química , Espectrometria de Massas por Ionização por Electrospray/métodos , Ácidos Linoleicos Conjugados/análise
14.
Anal Biochem ; 307(2): 348-60, 2002 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-12202254

RESUMO

Double bond position in natural fatty acids is critical to biochemical properties, however, common instrument-based methods cannot locate double bonds in fatty acid methyl esters (FAME), the predominant analysis form of fatty acids. A recently described mass spectrometry (MS) method for locating double bonds in FAME is reported here for the analysis of minor (<1%) components of real FAME mixtures derived from three natural sources; golden algae (Schizochytrium sp.), primate brain white matter, and transgenic mouse liver. Acetonitrile chemical ionization tandem MS was used to determine double bond positions in 39 FAME, most at concentrations well below 1% of all fatty acid methyl esters. FAME identified in golden algae are 14:1n-6, 14:3n-3, 16:1n-7, 16:2n-6, 16:3n-6, 16:3n-3, 16:4n-3, 18:2n-7, 18:3n-7, 18:3n-8, 18:4n-3, 18:4n-5, 20:3n-7, 20:4n-3, 20:4n-5, 20:4n-7, 20:5n-3, and 22:4n-9. Additional FAME identified in primate brain white matter are 20:1n-7, 20:1n-9, 20:2n-7, 20:2n-9, 22:1n-7, 22:1n-9, 22:1n-13, 22:2n-6, 22:2n-7, 22:2n-9, 22:3n-6, 22:3n-7, 22:3n-9, 22:4n-6, 24:1n-7, 24:1n-9, and 24:4n-6. Additional FAME identified in mouse liver are 26:5n-6, 26:6n-3, 28:5n-6, and 28:6n-3. The primate brain 22:3n-7 and algae 18:4n-5 are novel fatty acids. These results demonstrate the usefulness of the technique for analysis of real samples. Tables are presented to aid in interpretation of acetonitrile CIMS/MS spectra.


Assuntos
Acetonitrilas/química , Ácidos Graxos/análise , Ácidos Graxos/química , Espectrometria de Massas/métodos , Animais , Química Encefálica , Eucariotos/química , Fígado/química , Camundongos , Camundongos Transgênicos , Papio
15.
Mol Genet Metab ; 75(2): 108-19, 2002 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11855929

RESUMO

Extremely long chain polyunsaturated fatty acids (ELCPs) with >24 carbons and four or more double bonds are normally found in excitatory tissues but have no known function, and are greatly increased in brain and other tissues of humans with peroxisomal disorders. Straight-chain acyl-CoA oxidase (AOX) catalyzes the first, rate-limiting step of peroxisomal beta-oxidation of very-long-chain saturated and unsaturated fatty acids. We have studied the polyunsaturated fatty acid metabolism of AOX knockout mice (AOX-/- as a model of human AOX deficiency (pseudo-neonatal adrenoleukodystrophy), and as a genetic tool to test the putative peroxisomal beta-oxidation involvement in polyunsaturated fatty acid synthesis. Liver lipids of 26-day-old weanling AOX-/- mice livers accumulate n-3 and n-6 ELCPs from C24 to C30 with 5 and 6 double bonds, have 356 +/- 66 microg/g docosahexaenoic acid (22:6n-3), similar to congenic (AOX -/* = AOX+/+ and AOX+/-) controls (401 +/- 96 microg/g), but increased 22:5n-6 (22.4 +/- 3.7 vs 6.4 +/- 1.5 microg/g). AOX+/* mice injected intraperitoneally at 23 days with [U-(13)C]-18:3n-3 show strong labeling of 22:6n-3 after 72 h, whereas AOX -/- mice display less labeling of 22:6n-3 but strong tracer incorporation into 24:6n-3, 26:6n-3, and 28:6n-3, after the same period. These data suggest that ELCPs are natural runaway elongation by-products of 22:6n-3 and 22:5n-6 synthesis, which are normally disposed of by peroxisomal beta-oxidation. Under conditions with impaired peroxisomal beta-oxidation, such as Zellweger syndrome and adrenoleukodystrophies, ELCPs accumulate due to increased synthesis and impaired disposal. Two mechanisms for the formation of these runaway elongation by-products and the involvement of secondary carnitine deficiency in this process are proposed: n-3 ELCPs are synthesized by a carnitine-dependent multifunctional mitochondrial docosahexaenoic acid synthase (mtDHAS) which normally synthesizes primarily 22:6n-3, while n-6 ELCPs are synthesized by independent elongation enzymes in the endoplasmic reticulum.


Assuntos
Adrenoleucodistrofia/metabolismo , Ácidos Graxos/metabolismo , Oxirredutases/metabolismo , Transtornos Peroxissômicos/genética , Transtornos Peroxissômicos/metabolismo , Ácido alfa-Linolênico/metabolismo , Acil-CoA Oxidase , Adrenoleucodistrofia/genética , Animais , Modelos Animais de Doenças , Feminino , Humanos , Cinética , Masculino , Camundongos , Camundongos Knockout , Oxirredutases/genética
16.
Anal Chem ; 75(18): 4925-30, 2003 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-14674473

RESUMO

Fatty acids with conjugated double bonds have attracted great interest because of their reported potent bioactivities. However, there are currently no rapid methods for their structural characterization. We report here a convenient mass spectrometry-based strategy to establish double bond geometry by analysis of collisional dissociation products of cis/trans and trans/cis conjugated linoleic acids (CLAs), as methyl esters, and to distinguish CLAs from homoallylic (methylene-interrupted) fatty acids in a single-stage mass spectrum. A series of CLA standards with double bond positions 6,8; 7,9; 8,10; 9,11; 10,12; 11,13; 12,14; and 13,15, with all four possible geometries (cis/trans; trans/cis; cis/cis; trans/trans) were analyzed. The m/z 54 (1-methyleneimino)-1-ethenylium ion, generated by self-reaction of acetonitrile under chemical ionization conditions, reacts with unsaturated fatty acids to yield an [M + 54]+ ion, which decomposes in the single-stage mass spectrum by loss of neutral methanol to form [M + 54 - 32]+. The ratio of [M + 54]+/[M + 54 - 32]+ in the single-stage mass spectra of CLA isomers is 1 order of magnitude less than for homoallylic diene FAME. Collisional dissociation of the [M + 54]+ ion yields two diagnostic ions that contain the alpha- and omega-carbon atoms and is characteristic of double bond position in the analyte. The fragment vinylic to the trans double bond is significantly more abundant than that for the cis double bond, revealing double bond geometry. The ratio of alpha to we diagnostic ion abundances is >4.8 for cis/trans isomers, <0.5 for trans/cis isomers, and 0.7-3.2 for cis/cis and trans/trans isomers. This method provides a rapid alternative to conventional conjugated fatty acid analysis and, together with complementary elution time information provided by gas chromatography, enables rapid, positive identification of double bond position and geometry in most CLA FAME.


Assuntos
Ácidos Graxos/química , Espectrometria de Massas/métodos , Ésteres
17.
Anal Chem ; 74(2): 479-83, 2002 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-11817371

RESUMO

We present a rapid and selective method to increase the volatility of tyrosine and phenylalanine without adding derivative C for high-precision gas chromatography-continuous-flow isotope ratio mass spectrometry (GCC-IRMS) based on enzymatic decarboxylation to yield alkylamines and evaluated for 15N isotopic integrity. Purified tyrosine and phenylalanine were converted to tyramine and phenethylamine by tyrosine and phenylalanine decarboxylases, respectively. GC separation was achieved using a thick stationary phase (5-microm) capillary column. Recoveries were 95 +/- 2%. The reproducibility of delta15N of tyramine and phenethylamine measured by GCC-IRMS averaged SD(delta15N) = 0.33 per thousand. The absolute differences between delta15N of amino acids measured by elemental analyzer-IRMS and the alkylamines measured by GCC-IRMS was not significant. Phenethylamine and tyramine prepared from a mixture of 18 amino acids were extracted by ethanol with 95% recovery, and analysis yielded clean chromatograms and equivalent precision. These data indicate that enzymatic decarboxylation of phenylalanine and tyrosine is a convenient method to increase their volatility for continuous-flow isotopic analysis without introducing extraneous C or significant isotopic fractionation.


Assuntos
Aminoácidos/análise , Carboxiliases/metabolismo , Animais , Humanos , Isótopos/análise , Espectrometria de Massas , Fenilalanina/metabolismo , Tirosina/metabolismo
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