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1.
Pulmonology ; 2024 May 10.
Article in English | MEDLINE | ID: mdl-38734564

ABSTRACT

INTRODUCTION AND OBJECTIVES: Pulmonary rehabilitation (PR) is a fundamental intervention to manage COPD, however, maintaining its benefits is challenging. Engaging in physical activity might help to prolong PR benefits. This study assessed the efficacy and effectiveness of a personalised community-based physical activity programme to sustain physical activity and other health-related PR benefits, in people with COPD. MATERIALS AND METHODS: This was a multicentre, assessor blinded, randomised controlled trial. Following 12-weeks of PR, people with COPD were assigned to a six-months personalised community-based physical activity programme (experimental group), or to standard care (control group). Physical activity was assessed via: time spent in moderate to vigorous physical activities per day (primary outcome measure), steps/day and the brief physical activity assessment tool. Secondary outcomes included sedentary behaviour, functional status, peripheral muscle strength, balance, symptoms, emotional state, health-related quality of life, exacerbations and healthcare utilization. Assessments were performed immediately post-PR and after three- and six-months. Efficacy and effectiveness were evaluated using intention-to-treat and per-protocol analysis with linear mixed models. RESULTS: Sixty-one participants (experimental group: n = 32; control group: n = 29), with balanced baseline characteristics between groups (69.6 ± 8.5 years old, 84 % male, FEV1 57.1 ± 16.7 %predicted) were included. Changes in all physical activity outcomes and in one-minute sit-to-stand were significantly different (P < 0.05) between groups at the six-month follow-up. In the remaining outcomes there were no differences between groups. CONCLUSIONS: The community-based physical activity programme resulted in better physical activity levels and sit-to-stand performance, six-months after completing PR, in COPD. No additional benefits were observed for other secondary outcomes.

2.
Article in Portuguese | LILACS | ID: biblio-1353116

ABSTRACT

Nevo epidérmico verrucoso inflamatório linear e diagnóstico diferencial com a psoríase linear: a respeito de um caso RELATO DE CASOMaria Isabel Muniz Zemero1, Maria Amélia Lopes dos Santos1, Alena Margareth Darwich Mendes1, Carla Andrea Avelar Pires1,O nevo epidérmico verrucoso inflamatório linear (NEVIL) é uma variedade clínica rara de nevo epidérmico verrucoso, que se manifesta no início da infância, como lesões inflamatórias de superfície ceratósica, que coalescem e se distribuem em faixa, acompanhando as linhas de Blaschko. Faz diagnóstico diferencial com a psoríase linear, sendo difícil a diferenciação, dado os aspectos clínicos e histopatológicos comuns aos dois, enfantizando-se a necessidade de conhecer as características específicas de cada um. O objetivo deste relato é demonstrar uma afecção relativamente rara, descrita em uma menina de 5 anos, evoluindo desde os primeiros dias de vida com placas papuloceratósicas dispostas linearmente, acompanhadas de sinais inflamatórios e áreas erosadas ocupando grandes lábios, períneo e face interna e superior da coxa esquerda. Também pápulas e placas ceratósicas na região cervical posterior e borda lateral externa da planta do pé esquerdo, ascendendo ao longo da região posterior deste membro. Os critérios clínicos e histopatológicos corroboram o diagnóstico de NEVIL na diferenciação com a psoríase linear, ressaltando a importância do estabelecimento de critérios/ ferramentas que auxiliem na diferenciação destas duas dermatoses visando agilizar o diagnóstico, otimizar o tratamento e minimizar o desconforto para esses pacientes. O acompanhamento a longo prazo dos portadores é sugerido pela possibilidade ainda que mínima de malignização do NEVIL. (AU)


Inflammatory linear verrucous epidermal nevus and differential diagnosis with linear psoriasis: about a caseCASE REPORTMaria Isabel Muniz Zemero1, Maria Amélia Lopes dos Santos1, Alena Margareth Darwich Mendes1, Carla Andrea Avelar Pires1,Inflammatory Linear Verrucous Epidermal Nevus (ILVEN) is a rare clinical variety of verrucous epidermal nevus that manifests in early childhood as inflammatory lesions of keratosis surface, which coalesce and spread in band, following Blaschko lines. It makes a differential diagnosis with Linear Psoriasis; it is difficult to differentiate them given the clinical and histopathological aspects common to both, emphasizing the need to know the specific characteristics of each. The purpose of this report is to demonstrate a relatively rare affection, expressed in a 5-year-old girl, evolving from the first days of life with papulokeratosic plaques arranged linearly, followed by inflammatory signs and eroded areas, placed linearly, overtaking labia majora, perineum, the inner and upper face of the left thigh. Also, the patient showed keratotic papules and plaques in the posterior cervical region and external lateral border of the left foot plant, ascending along the posterior region of this limb. The clinical and histopathological criteria corroborate the diagnosis of ILVEN in differentiation with linear psoriasis, emphasizing the importance of establishing criteria/instruments to assist in distinguishing these two dermatoses in order to expedite the diagnosis, to optimize the treatment and minimize patients' discomfort. Long-term follow-up of patients with this disease is suggested due to the possibility, albeit minimal, of ILVEN malignancy. (AU)


Subject(s)
Humans , Female , Child, Preschool , Psoriasis , Skin Diseases , Diagnosis, Differential , Ectromelia , Nevus, Sebaceous of Jadassohn/diagnosis , Genitalia/pathology , Keratosis
3.
Arq. bras. med. vet. zootec. (Online) ; 73(3): 631-638, May-June 2021. tab, graf
Article in English | LILACS, VETINDEX | ID: biblio-1278371

ABSTRACT

The objective of this study was to determine changes on intraocular pressure (IOP) and pupil diameter (PD) in healthy cats anesthetized with isoflurane, and premedicated with acepromazine alone or in combination with tramadol. Thirty cats were allocated in two groups (n=15/each) and were treated with acepromazine (AG) or acepromazine/tramadol (ATG). PD and IOP were assessed before and following 30 (PM1), and 40 minutes (PM2) of treatments. Anesthesia was induced with propofol, and IOP and DP were recorded (A10) at 10 minute intervals until the end of anesthesia (A40). IOP decreased in AG and ATG, when comparing baseline with PM1. IOP decreased only in AG, in comparisons between baseline and PM2. During anesthesia, IOP did not change within and between groups. Comparisons between baseline with those recorded at PM1 and 2 showed that PD increased in the ATG. During anesthesia, PD decreased significantly in AG and ATG. Both protocols maintained the IOP within the reference range to perform corneal or intraocular surgery in healthy cats but did not sustain pre-anesthetic pupil dilation observed in ATG.(AU)


O objetivo do presente artigo é determinar possíveis alterações na pressão intraocular (PIO) e no diâmetro pupilar (DP) em gatos saudáveis anestesiados com isoflurano e pré-medicados com acepromazina isolada ou em combinação com acepromazina/tramadol. Trinta gatos saudáveis foram distribuídos aleatoriamente em dois grupos (n=15/cada) e tratados com acepromazina (GA) ou acepromazina/tramadol (GAT). DP e PIO foram avaliadas antes (basal) e após 30 (PM1) e 40 minutos (PM2) dos tratamentos. A anestesia foi induzida com propofol, e a PIO e o DP foram registrados (A10) a cada 10 minutos até o final da anestesia com isoflurano (A40). Ao se compararem os valores obtidos no basal com PM1, a PIO diminuiu em GA e GAT; com PM2, a PIO reduziu apenas no GA. Durante a anestesia, a PIO não diferiu dentro e entre os grupos. Comparações entre os valores basais e os registrados em PM1 e em PM2 mostraram que a DP aumentou significativamente no GAT. Durante a anestesia, o DP diminuiu significativamente em GA e GAT. Ambos os protocolos mantêm a PIO dentro dos valores de referência para realizar cirurgias corneanas ou intraoculares em gatos saudáveis, mas não sustentam a dilatação pupilar pré-anestésica observada em GAT.(AU)


Subject(s)
Animals , Cats , Tramadol/administration & dosage , Mydriasis/veterinary , Pupil/drug effects , Intraocular Pressure , Isoflurane/adverse effects , Acepromazine/administration & dosage , Tonometry, Ocular/veterinary , Anesthetics, General/administration & dosage
4.
J Appl Microbiol ; 131(1): 272-280, 2021 Jul.
Article in English | MEDLINE | ID: mdl-33211380

ABSTRACT

AIMS: This study evaluated the microbiological quality and safety of minimally processed parsley sold in southeastern Brazilian food markets. METHODS AND RESULTS: One hundred samples were submitted to the enumeration of Enterobacteriaceae by plating on MacConkey agar. Colonies of Enterobacteriaceae were randomly selected and identified by MALDI-TOF MS. Samples were also tested for Listeria monocytogenes and Salmonella sp. The mean count of Enterobacteriaceae was 6·0 ± 1·0 log CFU per gram, while 18 genera (including 30 species) of bacteria belonging to this family were identified. Salmonella and L. monocytogenes were not detected, while L. innocua was found in two samples and L. fleischmannii was found in one sample. Moreover generic Escherichia coli was found in three samples, all from different brands of minimally processed parsley. CONCLUSIONS: Even though microbial pathogens were not isolated, a variety of indicator micro-organisms were identified, including vegetable spoilers and species capable of causing human opportunistic infections. These results suggest hygienic failures and/or lack of temperature control during processing and storage of these ready-to-eat products. SIGNIFICANCE AND IMPACT OF STUDY: This study highlights the need for control measures during the production chain of minimally processed parsley in order to reduce microbial contamination and the risks of foodborne diseases.


Subject(s)
Enterobacteriaceae/isolation & purification , Food Microbiology , Food Safety , Listeria/isolation & purification , Petroselinum/microbiology , Bacterial Load , Brazil , Enterobacteriaceae/growth & development , Escherichia coli/isolation & purification , Food Contamination , Foodborne Diseases , Listeria/growth & development , Listeria monocytogenes/growth & development , Listeria monocytogenes/isolation & purification , Salmonella/isolation & purification
5.
Lett Appl Microbiol ; 71(2): 187-194, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32365403

ABSTRACT

The present study shows the results of the microbiological quality and safety of minimally processed vegetables sold in supermarkets and grocery stores located in the city of Piracicaba, SP, Brazil. A total of 100 samples were collected and submitted to enumeration of total coliforms, coliforms at 45°C and generic Escherichia coli using the standard most probable number (MPN) method, in addition to enumeration of total Enterobacteriaceae by plating on MacConkey agar. Moreover, colonies of Enterobacteriaceae were randomly selected and submitted to identification on a MALDI-TOF MS Biotyper™. Samples were also tested for Salmonella spp. according to the ISO 6579:2002 method. The mean count of total coliforms was 2·9 ± 0·5 log MPN per g. For coliforms at 45°C, 20 samples were positive (mean 1·5 ± 1·0 log MPN per g). Generic E. coli was detected in 16 samples (mean 1·4 ± 0·9 log MPN per g) and only one was positive for Salmonella. The mean count of total Enterobacteriaceae was 6·5 ± 1·2 log CFU per g and the most frequent genera identified by MALDI-TOF were Enterobacter (25·9%), Pantoea (9·6%) and Rahnella (9·0%). Overall, results point to poor microbiological quality of a few samples, indicating hygiene failure during their processing. This can pose health risks to consumers, mainly because these products were labelled as sanitized and marketed as ready-to-eat. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study, the microbiological quality and safety of minimally processed vegetables sold in the city of Piracicaba, SP, Brazil, were evaluated through the detection of Salmonella spp., generic Escherichia coli and other Enterobacteriaceae. The results obtained point to poor microbiological quality and safety of a few samples, as generic E. coli was detected in 16 out of 100 samples and Salmonella was isolated from one of them. This indicates hygiene failures during their processing and health risk to consumers, since these products are usually sold as ready-to-eat and typically require no further heat treatment before consumption.


Subject(s)
Escherichia coli/isolation & purification , Food Contamination/analysis , Food Safety/methods , Salmonella/isolation & purification , Vegetables/microbiology , Brazil , Colony Count, Microbial , Culture Media , Food Microbiology , Humans , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
7.
Scand J Med Sci Sports ; 28(8): 1934-1945, 2018 Aug.
Article in English | MEDLINE | ID: mdl-29542188

ABSTRACT

Objective methods to measure physical activity (PA) have become available and widely used given the high degree of precision to evaluate PA. However, few studies have used accelerometers to measure PA during pregnancy, especially in low- and middle-income countries. We assessed overall PA, moderate, vigorous, and moderate-to-vigorous physical activity (MVPA) objectively measured among pregnant women and their correlates in a population-based study. PA was assessed for seven consecutive days using a raw triaxial wrist-worn accelerometer in women interviewed around 16 and 24 weeks of gestation in the 2015 Pelotas (Brazil) Birth Cohort Study. The average acceleration, which expresses overall PA, was presented in milli-g (1 mg = 0.001 g), and average time (min/day) spent in MVPA (>100 mg) was also analyzed in 5- and 10-min bouts. Analyses were performed using linear regression. In total, 2317 women were included in the analyses. Overall PA was 27.6 mg. Pregnant women spent on average 14 min/day in MVPA and 0.4 min in vigorous PA. Time spent in MVPA and total PA were inversely associated with years in school and income, and were lower among women receiving advice to not exercise. MVPA was also inversely associated with age, lower among women living with a partner, and higher among non-white women. The study indicated low levels of PA among pregnant women. The identified correlates may provide a framework to better understand factors influencing PA during pregnancy and thus inform future interventions.


Subject(s)
Exercise , Pregnancy , Accelerometry , Adult , Brazil , Cohort Studies , Female , Humans , Socioeconomic Factors , Young Adult
8.
Rapid Commun Mass Spectrom ; 29(3): 295-303, 2015 Feb 15.
Article in English | MEDLINE | ID: mdl-26411627

ABSTRACT

RATIONALE: Due to increases in greenhouse gas emissions, it is necessary to explore renewable sources of energy. Interesting alternatives are biofuels derived from microalgae. One challenge is the development of a detailed microalgae database compiling species identifications and characterizations that would facilitate microalgae selection for biomass production. Mass spectrometric (MS) analysis using a matrix-assisted laser desorption/ionization (MALDI) source is an advanced technique that enables advancement in this biological area. In this work a MALDI time-of-flight (TOF)MS method for the rapid identification of proteins in whole cells of selected microalgae species was studied. Furthermore, the efficiency of different matrix and solvent systems was tested. MS analyses were performed using an UltrafleXtreme MALDI-TOF mass spectrometer operating in linear positive ion mode. METHODS: Mass spectra were acquired in a mass range from 4000 to 20,000 Da with ions generated from Smartbeam laser irradiation using a frequency of 2000 Hz, a PIE 100 ns and a lens 7 kV. The voltage was 25 kV for the first ion source and 23 kV for the second. Each spectrum was generated by averaging of 10,000 laser shots and the laser irradiance was set at 95-100%. RESULTS: Similar mass spectra were obtained for all matrices (SA, HCCA, DHB and sDHB); however, the use of the sDHB matrix resulted in spectrum profiles with a greater amount number of proteins, a better signal/noise (S/N) ratio and higher intensities for the majority of microalgae analyzed. Trifluoroacetic acid (TFA) content was also studied and the best results in terms of S/N ratio, number of proteins and signal intensities were obtained with 0.1% TFA in the matrix solvent. The addition of isopropanol did not produce improvement in the quality of spectrum profiles. CONCLUSIONS: Therefore, the optimal matrix for the analysis of protein from intact microalgae cells is sDHB with TA50 as the matrix solvent and without isopropanol. These conditions allow the acquisition of high quality spectrum profiles.


Subject(s)
Chlorella/chemistry , Microalgae/chemistry , Freeze Drying , Solvents , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods
9.
J Phys Chem B ; 117(17): 4870-9, 2013 May 02.
Article in English | MEDLINE | ID: mdl-23528077

ABSTRACT

Pyrogallol red (PGR) presents high reactivity toward reactive (radical and nonradical) species (RS). This property of PGR, together with its characteristic spectroscopic absorption in the visible region, has allowed developing methodologies aimed at evaluating the antioxidant capacity of foods, beverages, and human fluids. These methods are based on the evaluation of the consumption of PGR induced by RS and its inhibition by antioxidants. However, at present, there are no reports regarding the degradation mechanism of PGR, limiting the extrapolation to how antioxidants behave in different systems comprising different RS. In the present study, we evaluate the kinetics of PGR consumption promoted by different RS (peroxyl radicals, peroxynitrite, nitrogen dioxide, and hypochlorite) using spectroscopic techniques and detection of product by HPLC mass spectrometry. The same pattern of oxidation and spectroscopic properties of the products is observed, independently of the RS employed. Mass analysis indicates the formation of only one product identified as a quinone derivative, excluding the formation of peroxides or hydroperoxides and/or chlorinated compounds, in agreement with FOX's assays and oxygen consumption experiments. Cyclic voltammetry, carried out at different pH's, shows an irreversible oxidation of PGR, indicating the initial formation of a phenoxy radical and a second charge transfer reaction generating an ortho-quinone derivative. Spectroelectrochemical oxidation of PGR shows oxidation products with identical UV-visible absorption properties to those observed in RS-induced oxidation.


Subject(s)
Antioxidants/chemistry , Free Radicals/chemistry , Pyrogallol/analogs & derivatives , Reactive Oxygen Species/chemistry , Chromatography, High Pressure Liquid , Electrochemical Techniques , Humans , Hydrogen Peroxide/chemistry , Hydrogen Peroxide/metabolism , Hydrogen-Ion Concentration , Kinetics , Oxidation-Reduction , Pyrogallol/chemistry , Pyrogallol/metabolism , Spectrophotometry, Ultraviolet , Tandem Mass Spectrometry
10.
Scand J Med Sci Sports ; 19(1): 67-74, 2009 Feb.
Article in English | MEDLINE | ID: mdl-18248541

ABSTRACT

Nitric oxide (NO) inhibits platelet function and plays a key role in the regulation of cardiovascular homeostasis. Essential hypertension is characterized by an increased risk of thrombus formation, and by an inhibition of intraplatelet NO bioactivity. We have previously shown that membrane transport of L-arginine is a rate-limiting step for platelet-derived NO synthesis. This study examined the effects of exercise on the platelet L-arginine-NO pathway and aggregation and systemic inflammation markers in 13 sedentary hypertensive patients subjected to 60 min of training activity (exercise group), predominantly aerobic, three times a week for a period of 12 weeks. Six sedentary hypertensive patients participated in the control group. After 12 weeks, L-arginine transport was significantly increased and associated with increased platelet NO synthase activity and cGMP levels and reduced platelet aggregation. Moreover, exercise training reduced plasma concentrations of fibrinogen and C-reactive protein and blood pressure. The control group did not change their previous intraplatelet L-arginine-NO results and systemic inflammatory markers levels. Thus, exercise training reduces inflammatory responses, restores NO synthesis in platelets and thereby contributes to the beneficial effects of exercise in hypertension. The present study adds exercise as a new tool to reduce morbidity and mortality associated with platelet activation in hypertension.


Subject(s)
Arginine/metabolism , Exercise/physiology , Hypertension/physiopathology , Nitric Oxide/metabolism , Platelet Activation/physiology , Arginine/analysis , Brazil , Exercise Test , Female , Humans , Male , Middle Aged , Nitric Oxide/analysis
11.
Vet Immunol Immunopathol ; 88(3-4): 163-72, 2002 Sep 25.
Article in English | MEDLINE | ID: mdl-12127414

ABSTRACT

Three synthetic peptides (SBm4912, SBm7462 and SBm19733), derived from the Bm86 glycoprotein from Boophilus microplus gut, were constructed and used to immunize cattle from a tick-free area. The immunized animals received three subcutaneous doses of the peptides, with saponin as adjuvant, at 30-day intervals. The immune response was evaluated by IgG elicited against the peptides by the detection of anti-Bm86 specific antibodies in situ and by Western blotting analysis. After tick challenge, reduction in the number, weight and oviposition capacity of engorged females was observed in the tick population that had fed on immunized animals. The results pointed a high efficacy (81.05%) for the SBm7462 synthetic peptide in relation to the others (p<0.01), demonstrating the efficiency of the immune response elicited by synthetic peptides to control the cattle tick B. microplus.


Subject(s)
Cattle Diseases/prevention & control , Cattle/immunology , Membrane Glycoproteins/immunology , Peptide Fragments/chemical synthesis , Peptide Fragments/immunology , Recombinant Proteins , Tick Infestations/prevention & control , Vaccines, Synthetic/immunology , Vaccines , Animals , Blotting, Western , Body Weight , Cattle Diseases/immunology , Cattle Diseases/parasitology , Enzyme-Linked Immunosorbent Assay , Female , Immunoglobulin G/immunology , Ixodidae/immunology , Membrane Glycoproteins/chemistry , Oviposition , Peptide Fragments/administration & dosage , Peptide Fragments/chemistry , Tick Infestations/immunology , Tick Infestations/parasitology , Tick Infestations/veterinary , Vaccination/methods , Vaccination/veterinary , Vaccines, Synthetic/administration & dosage
12.
Analyst ; 126(8): 1212-5, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11534582

ABSTRACT

Trap and release membrane introduction mass spectrometry (T&R-MIMS) using a removable direct insertion membrane probe (DIMP) is employed to determine the total homocysteine concentration (tHcy) directly from human plasma after derivatization with ethyl chloroformate. The method uses no chromatographic separation, is linear, reproducible, and displays limit of quantitation (2 pM) sufficiently below the threshold concentration of tHcy in plasma. It also combines chemical, membrane, and mass spectrometric discrimination, and can be used to determine selected amino acids in human plasma simultaneously. After derivatization with ethyl chloroformate, many amino acids in aqueous solution are observed to be efficiently detected; hence T&R-MIMS is promising as a simple and sensitive technique for simultaneous quantitation of selected amino acids in plasma and urine, and in other aqueous matrices.


Subject(s)
Homocysteine/blood , Humans , Mass Spectrometry/methods
13.
J Am Soc Mass Spectrom ; 12(1): 14-22, 2001 Jan.
Article in English | MEDLINE | ID: mdl-11142356

ABSTRACT

Primary carboxonium (H2C=O+-R) and carbosulfonium (H2C=S+-R) ions (R = CH3, C2H5, Ph) and the prototype five-membered cyclic carboxonium ion are found to react in the gas phase with cyclic acetals and ketals by transacetalization to form the respective O-alkyl-1,3-dioxolanium and S-alkyl-1,3-oxathiolanium ions. The reaction, which competes mainly with proton transfer and hydride abstraction, initiates by O-alkylation and proceeds by ring opening and recyclization via intramolecular displacement of the carbonyl compound previously protected in its ketal form. As indicated by product ion mass spectra, and confirmed by competitive reactions, carbosulfonium ions are, by transacetalization, much more reactive than carboxonium ions. For acyclic secondary and tertiary carboxonium ions bearing acidic alpha-hydrogens, little or no transacetalization occurs and proton transfer dominates. This structurally related reactivity distinguishes primary from both secondary and tertiary ions, as exemplified for the two structural isomers H2C=O+-C2H5 and CH3C(H)=O+-CH3. The prototype five- and six-membered cyclic carboxonium ions react mainly by proton transfer and adduct formation, but the five-membered ring ion also reacts by transacetalization to a medium extent. Upon CID, the transacetalization products of the primary ions often dissociate by loss of formaldehyde, and a +44 u neutral gain/-30 u neutral loss MS3 scan is shown to efficiently detect reactive carboxonium and carbosulfonium ions. Transacetalization with either carboxonium or carbosulfonium ions provides a route to 1,3-oxathiolanes and analogs alkylated selectively either at the sulfur or oxygen atom.

14.
Analyst ; 125(1): 211-5, 2000 Jan.
Article in English | MEDLINE | ID: mdl-10885076

ABSTRACT

This paper presents the first membrane inlet mass spectrometry system capable of detecting large biomolecules, such as testosterone (M(r) 288), testosterone acetate (M(r) 330) and alpha-tocopherol (M(r) 430, vitamin E). The result was obtained using a home-made chemical ionization ion source with a thermostated tubular silicone membrane mounted right in the centre of a methane CI plasma. The liquid sample was flushed through the inside of the membrane for a period of 20-25 min, where the analyte diffused into the membrane. Following this trapping period the analyte was released from the membrane into the mass spectrometer by the combined action of heat radiation from the filament and charge transfer from the chemical ionization plasma. As a result of this stimulated desorption a good desorption peak was obtained as the analyte vaporized out of the membrane. Retinol (M(r) 286, vitamin A), cholecalciferol (M(r) 384, vitamin D3) and cholesterol (M(r) 386) were also detected. However, these compounds (all containing a long hydrocarbon chain and being aliphatic alcohols) did not give a protonated molecule. They gave a series of cluster ions with the dominant located 20 mass units below the molecular ion. The detection limits of the new desorption chemical ionization MIMS technique were at low or sub-micromolar concentrations (high ppb levels) and the reproducibility was within 20%, when the area of the desorption peak was used for quantitation.


Subject(s)
Testosterone/analysis , Vitamin E/analysis , Humans , Macromolecular Substances , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
15.
J Mass Spectrom ; 35(2): 189-98, 2000 Feb.
Article in English | MEDLINE | ID: mdl-10679981

ABSTRACT

A novel gas-phase reaction of diacylium ions of the O=C=X(+)=C=O type (X = N, CH) is reported: double transacetalization with cyclic acetals or ketals. The reaction is exothermic and highly efficient, and forms members of a new class of highly charged-delocalized ions: cyclic ionic diketals. Pentaquadrupole double- and triple-stage mass spectrometric (MS(2) and MS(3)) experiments reveal the high double transacetalization reactivity of O=C=N(+)=C=O and O=C=CH(+)=C=O, whereas the synthesis of differently substituted cyclic ionic diketals is performed in MS(3) experiments via sequential mono- and double transacetalization of O=C=N(+)=C=O and O=C=CH(+)=C=O with different acetals. With cyclic acetals, the acylium-thioacylium ion O=C=N(+)=C=S reacts promptly and selectively by mono-transacetalization at its acylium site, but the free thiacylium site of its cyclic ionic ketal is nearly unreactive by double transacetalization. Therefore, only the acylium site of O=C=N(+)=C=S can be efficiently protected by transacetalization. Low-energy MS(3) collision-induced dissociation of the cyclic ionic diketals of O=C=N(+)=C=O and O=C=CH(+)=C=O sequentially frees each of the protected acylium site to form the mono-derivatized ion, and then the fully deprotected diacylium ion.


Subject(s)
Acetals/chemistry , Isocyanates/chemistry , Mass Spectrometry
16.
Chemistry ; 6(2): 321-6, 2000 Jan.
Article in English | MEDLINE | ID: mdl-11931112

ABSTRACT

Two ortho-hetarynium ions, the 2-pyridyl and 2-pyrimidyl cations, react promptly with 1,3-dienes in the gas phase by annulation, formally by fusion, onto the ions of a pyrrole ring. This novel reaction proceeds through an initial polar [4 + 2+] cycloaddition across the C[triple bond]N+ bond, followed by fast ring opening, a [1,4-H] shift, and finally a recyclization that results in a contraction of a six- to a five-membered ring and dissociation by the loss of a methyl radical. For the 2-pyridyl cation, this reaction yields ionized indolizines (pyrrolo[1,2-a]pyridines), while for the 2-pyrimidyl cation, it gives ionized pyrrolo[1,2-a]pyrimidines. The annulation reaction, performed in the rf-only collision quadrupole of a pentaquadrupole (QqQqQ) mass spectrometer, occurs readily with both 1,3-butadiene and isoprene, and is thermodynamically and kinetically favored as predicted by ab initio calculations. Ortho-hetarynium ions and 1,3-dienes provide, therefore, the two building blocks for the efficient one-step gas-phase synthesis of ionized bicyclic pyrrolo[1,2-a]pyridine (indolizine) and pyrrolo[1,2-a]pyrimidine, as well as their analogues and derivatives.

17.
Anal Chem ; 68(19): 3502-6, 1996 Oct 01.
Article in English | MEDLINE | ID: mdl-21619284

ABSTRACT

Detection of volatile organic compounds (VOCs) in aqueous solution at low parts-per-trillion (ppt) levels is accomplished using a very simple and efficient on-line preconcentration cryotrap membrane introduction mass spectrometry (CT-MIMS) system. The conventional MIMS probe is modified so that the membrane interface is placed about 15 cm away from the ion source. A U-shaped trap tube is then inserted between the membrane interface and the ion source. Cryotrapping is performed with liquid nitrogen for 15 min, followed by fast heating at ∼15 °C s(-)(1), which thermally releases the condensed VOCs almost at once into the ion source region of a quadrupole mass spectrometer. By applying electron ionization and a selective ion monitoring scan mode, a very sharp and intense peak is obtained. The performance of the CT-MIMS system was compared with that of conventional MIMS, and after reaching the best conditions for the trapping and heating cycles, an improvement factor in signal intensity of about 100 was observed for a series of VOCs. The extraordinary sensitivity of CT-MIMS system allows VOCs to be detected at very low concentrations, detection limits being typically on the order of 10-20 ppt. The results also show excellent linearity and reproducibility for the system.

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