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1.
Lasers Surg Med ; 2024 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-38888133

RESUMEN

OBJECTIVES: This study aims to assess the thermal safety profile of the BeShape One Device, a noninvasive, high-intensity, non-focused ultrasound device designed for reducing waist circumference. This device possesses several features that distinguish it from other commercial ultrasound-based fat reduction devices. The study focuses on evaluating temperature-related physiological changes through thermal safety analysis and histopathology in a swine model. MATERIALS AND METHODS: The study utilized three types of applicators-active, demo, and modified-to comprehensively assess the device's impact on various skin layers. Five female Large White X Landrace swine were involved in the study, and the BeShape One Device was applied to designated treatment sites using a specific treatment protocol. The assessment included clinical observations, skin reaction evaluations, gross pathology, histopathological analyses, and advanced temperature measurement techniques, including needle thermocouples, thermal cameras, COMSOL modeling, and CEM43 analysis. RESULTS: Clinical observations indicated the animals' overall well-being throughout the study. Skin reactions, including erythema, edema, bruising, and crust formation, were temporary and resolved over time. Gross pathology revealed no treatment-related pathologies, except for a discoloration related to a tattoo procedure. Histopathological analyses at 30 and 90 days posttreatment demonstrated an absence of heat-related lesions in skin layers. Needle thermocouples and thermal camera measurements supported the device's ability to maintain consistent thermal homogeneity. COMSOL modeling and CEM43 analysis predicted no thermal damage to the skin, confirming the safety of the BeShape One Device. CONCLUSIONS: Under the experimental conditions, the BeShape One Device demonstrated a favorable safety profile. Clinically and histopathologically, no adverse effects were observed. The device's ability to achieve thermal homogeneity in skin layers was validated through advanced temperature measurement techniques. COMSOL modeling and CEM43 analysis further supported the conclusion that the device is safe, making it a promising option for noninvasive body contouring procedures.

2.
Rapid Commun Mass Spectrom ; 29(23): 2287-92, 2015 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-26522322

RESUMEN

RATIONALE: Library-based compound identification with electron ionization (EI) mass spectrometry (MS) is a well-established identification method which provides the names and structures of sample compounds up to the isomer level. The library (such as NIST) search algorithm compares different EI mass spectra in the library's database with the measured EI mass spectrum, assigning each of them a similarity score called 'Match' and an overall identification probability. Cold EI, electron ionization of vibrationally cold molecules in supersonic molecular beams, provides mass spectra with all the standard EI fragment ions combined with enhanced Molecular Ions and high-mass fragments. As a result, Cold EI mass spectra differ from those provided by standard EI and tend to yield lower matching scores. However, in most cases, library identification actually improves with Cold EI, as library identification probabilities for the correct library mass spectra increase, despite the lower matching factors. METHODS: This research examined the way that enhanced molecular ion abundances affect library identification probability and the way that Cold EI mass spectra, which include enhanced molecular ions and high-mass fragment ions, typically improve library identification results. It involved several computer simulations, which incrementally modified the relative abundances of the various ions and analyzed the resulting mass spectra. RESULTS: The simulation results support previous measurements, showing that while enhanced molecular ion and high-mass fragment ions lower the matching factor of the correct library compound, the matching factors of the incorrect library candidates are lowered even more, resulting in a rise in the identification probability for the correct compound. CONCLUSIONS: This behavior which was previously observed by analyzing Cold EI mass spectra can be explained by the fact that high-mass ions, and especially the molecular ion, characterize a compound more than low-mass ions and therefore carries more weight in library search identification algorithms. These ions are uniquely abundant in Cold EI, which therefore enables enhanced compound characterization along with improved NIST library based identification.

3.
J Am Soc Mass Spectrom ; 32(4): 929-935, 2021 Apr 07.
Artículo en Inglés | MEDLINE | ID: mdl-33779170

RESUMEN

Deriving elemental formulas from mass spectra used to be an exclusive feature provided only by expensive high-resolution mass spectrometry instruments. Nowadays this feature can be used on unit resolution quadrupole-based mass spectrometers (MS) combining isotope abundance analysis (IAA) and mass accuracy analysis (MAA) with surprising accuracy that is commonly lower than 1 ppm mass accuracy. In this Article, we assess the usefulness of both MAA and IAA in the elemental formula deriving process performed on unit resolution MS data with constant resolution across the m/z range. The methods' effective filtration power (EFP) are estimated along with their ability to provide useful elemental information under nonideal experimental conditions. The term effective mass accuracy (EMA) is introduced so that the identification power of IAA can be expressed in a familiar way and compared more readily to MAA. We found that IAA alone commonly has an EMA under 5 ppm. IAA and MAA work well together and provide improved results with median EMA < 1 ppm for calibrated MS or <3 ppm for uncalibrated MS. We have also found that even though these methods cannot be fully trusted to pinpoint the exact elemental formula under poor experimental conditions, IAA can still accurately provide the exact number of several heteroatoms such as sulfur, chlorine, and bromine, while MAA cannot. Under such conditions, a combination of both methods can also provide good insight into the amount of carbon, hydrogen, and other elements in the elemental formula.

4.
J Chromatogr A ; 1657: 462576, 2021 Nov 08.
Artículo en Inglés | MEDLINE | ID: mdl-34601255

RESUMEN

Today, labs that carry out chemical analyses for regulation, food safety, health, forensics, or even security purposes are looking for ways to accelerate the analytical process. Slow procedures are costly because the necessary instruments are expensive and require maintenance and a highly trained staff to operate them. One of the more ubiquitous instruments in such labs is a Gas Chromatograph (GC), which accepts a solution and outputs each of the compounds within it in a gaseous form, one by one to be further analyzed and identified, usually by a Mass Spectrometer (MS). This separation process in a GC can be rather time-consuming, partly due to the slow heating and cooling of the GC column through which the compounds move, which happens inside a box-shaped oven. This paper describes a controller developed for a unique Open Probe Fast GC instrument that enables, among other things, high-speed and controlled heating and cooling of a gas-carrying capillary transfer line. Fast heating is achieved by precisely controlling the electrical current flowing through the small inner-diameter steel tube through which the GC column passes. The fast cooling occurs by exposing the low-mass heated tube to room temperature, along with the assistance of a simple fan that carries the heated air away. This technology also supports control of other system parts, including a unique quick sampling device called an Open Probe that allows for an even faster analysis cycle. Our design is based entirely on a digital signal processor (DSP) and digital control. The use of pulse width modulation (PWM) control enables a compact and efficient system.


Asunto(s)
Calefacción , Calor , Cromatografía de Gases , Gases , Humanos
5.
Rapid Commun Mass Spectrom ; 23(23): 3668-72, 2009 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19899190

RESUMEN

Tandem mass spectrometry (MS/MS) is widely used for trace level sample analysis in complex mixtures. However, sample identification in MS/MS is challenging and not as trustworthy as with electron ionization (EI) mass spectral libraries. This paper presents a novel method for the combination of isotope abundance analysis (IAA) and EI-MS/MS for improved sample identification even at trace level in complex matrices. Accordingly, the first quadrupole is scanned in a narrow range around the molecular ion group of isotopomers such as M+, [M+1]+ and [M+2]+, Q2 serves for collision-induced dissociation to produce product ions while Q3 transfers the major sample product ions with low resolution, thus encompassing and uniformly transmitting all the product ion isotopomers. IAA can then be used to derive elemental formula information from the cleansed experimental data. IAA-MS/MS was experimentally tested with perfluorotributylamine and a very good matching factor of 995 (out of 1000) was obtained for IAA on m/z 502, 503 and 504 (fragment ion isotopomers) while Q3 transmitted the m/z 264 product ion with a mass window of 6 m/z units. The IAA-MS/MS method was further tested with the pesticide diazinon on its molecular ions m/z 304, 305 and 306 while Q3 was locked on its m/z 179 product ion with a mass window of 6 m/z units. Again, very good matching factors were obtained, even for 40 pg diazinon on-column during its GC/MS analysis (match = 981). IAA-MS/MS combines the traditional benefits of MS/MS in the removal of matrix interferences with the IAA power of elemental analysis.

6.
J Mass Spectrom ; 52(10): 638-642, 2017 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-28685904

RESUMEN

We report the observation of a new physical phenomenon of the addition of 2 hydrogen atoms to molecular ions thus forming [M + 2H]+ ions. We demonstrate such second hydrogen atom abstraction onto the molecular ions of pentaerythritol and trinitrotoluene (TNT). We used both gas chromatography mass spectrometry (GC-MS) with supersonic molecular beam (SMB) with methanol added into its make-up gas and electron ionization (EI) liquid chromatography mass spectrometry (LC-MS) with SMB with methanol as the LC solvent. We found that the formation of methanol clusters resulted upon EI in the formation of dominant protonated pentaerythritol ion at m/z = 137 plus about 70% relative abundance of pentaerythritol molecular ion with 2 additional hydrogen atoms at m/z = 138 which is well above the 5.7% natural C13 isotope abundance of protonated pentaerythritol. Similarly, we found an abundant protonated TNT ion at m/z = 228 and a similar abundance of TNT molecular ion with 2 additional hydrogen atoms at m/z = 229. Upon the use of deuterated methanol (CD3 OD) as the solvent, we observed an abundant m/z = 231 (M + 2D)+ of TNT with 2 deuterium atoms. We found such abundant second hydrogen atom abstraction with butylglycolate and at low abundances in dioctylphthalate, Vitamin K3, phenazine, and RDX. At this time, we are unable to report the magnitude and frequency of occurrence of this phenomenon in standard electrospray LC-MS. This observation could have important implications on the provision of elemental formula from mass spectra that are involved with protonated molecules. Accordingly, while accurate mass measurements can serve for the generation of elemental formula, their further support and improvement via isotope abundance analysis are questionable. Consequently, if a given compound can be analyzed by both GC-MS and LC-MS, its GC-MS analysis can be superior for the provision of accurate elemental formulae if its EI mass spectrum exhibits abundant molecular ions such as with GC-MS with SMB (also known as cold EI).

7.
J Chromatogr A ; 1129(1): 95-104, 2006 Sep 29.
Artículo en Inglés | MEDLINE | ID: mdl-16834991

RESUMEN

A new approach of flow modulation comprehensive two-dimensional gas chromatography-mass spectrometry (GC x GC-MS) with supersonic molecular beam (SMB) and a quadrupole mass analyzer is presented. Flow modulation uniquely enables GC x GC-MS to be achieved even with the limited scan speed of quadrupole MS, and its 20 ml/min column flow rate is handled, splitless, by the SMB interface. Flow modulation GC x GC-SMB-MS shares all the major benefits of GC x GC and combines them with GC-MS including: (a) increased GC separation capability; (b) improved sensitivity via narrower GC peaks; (c) improved sensitivity through reduced matrix interference and chemical noise; (d) polarity and functional group sample information via the order of elution from the second polar column. In addition, GC x GC-SMB-MS is uniquely characterized by the features of GC-MS with SMB of enhanced and trustworthy molecular ion plus isotope abundance analysis (IAA) for improved sample identification and fast fly-through ion source response time. The combination of flow modulation GC x GC with GC-MS with SMB (supersonic GC-MS) was explored with complex matrices such as diesel fuel analysis and pesticide analysis in agricultural products.


Asunto(s)
Cromatografía de Gases/métodos , Cromatografía de Gases y Espectrometría de Masas/métodos , Coriandrum/química , Diazinón/análisis , Contaminantes Ambientales/análisis , Gasolina/análisis , Compuestos Organotiofosforados/análisis , Plaguicidas/análisis , Reproducibilidad de los Resultados
8.
J Mass Spectrom ; 50(11): 1252-63, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26505770

RESUMEN

A new type of electron ionization LC-MS with supersonic molecular beams (EI-LC-MS with SMB) is described. This system and its operational methods are based on pneumatic spray formation of the LC liquid flow in a heated spray vaporization chamber, full sample thermal vaporization and subsequent electron ionization of vibrationally cold molecules in supersonic molecular beams. The vaporized sample compounds are transferred into a supersonic nozzle via a flow restrictor capillary. Consequently, while the pneumatic spray is formed and vaporized at above atmospheric pressure the supersonic nozzle backing pressure is about 0.15 Bar for the formation of supersonic molecular beams with vibrationally cold sample molecules without cluster formation with the solvent vapor. The sample compounds are ionized in a fly-though EI ion source as vibrationally cold molecules in the SMB, resulting in 'Cold EI' (EI of vibrationally cold molecules) mass spectra that exhibit the standard EI fragments combined with enhanced molecular ions. We evaluated the EI-LC-MS with SMB system and demonstrated its effectiveness in NIST library sample identification which is complemented with the availability of enhanced molecular ions. The EI-LC-MS with SMB system is characterized by linear response of five orders of magnitude and uniform compound independent response including for non-polar compounds. This feature improves sample quantitation that can be approximated without compound specific calibration. Cold EI, like EI, is free from ion suppression and/or enhancement effects (that plague ESI and/or APCI) which facilitate faster LC separation because full separation is not essential. The absence of ion suppression effects enables the exploration of fast flow injection MS-MS as an alternative to lengthy LC-MS analysis. These features are demonstrated in a few examples, and the analysis of the main ingredients of Cannabis on a few Cannabis flower extracts is demonstrated. Finally, the advantages of EI-LC-MS with SMB are listed and discussed.

9.
J Diabetes Sci Technol ; 9(3): 639-43, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25883166

RESUMEN

BACKGROUND: Delays in the time-action profiles of premeal boluses of rapid-acting insulin analogs contribute to early postmeal hyperglycemia in patients with diabetes. We tested whether applying local heat to skin around the injection site to increase the rate of insulin absorption reduces postprandial hyperglycemia in patients with type 2 diabetes. METHODS: Fourteen patients with type 2 diabetes (4 females; age 61.6 ± 8.4 years, HbA1c 8.42 ± 1.13%; BMI 29.10 ± 5.61 kg/m(2)) on intensified insulin therapy underwent 5-hour meal tolerance tests (MTTs) with a standardized liquid meal after an overnight fast on 2 study days. Subjects injected 0.2 U/kg of insulin aspart or lispro subcutaneously into the abdominal skin on both days with and without the use of the InsuPad device. RESULTS: Following the premeal bolus injection of rapid-acting insulin analog, infusion site warming led to a rise in plasma insulin levels to peak concentrations that were significantly earlier than without skin warming (mean ± SD 52 ± 26.7 vs 80 ± 51.3 minutes, P < .005) as well as increase in plasma insulin levels during the first hour after injection (mean ± SD 63.5 ± 32.7 IU vs 48.0 ± 25.0 uU.min/ml, P = .019). As a result, the area under the curve of the postprandial glucose excursion during the first 2 hours (the primary study outcome) and the entire 5 hours after the meal were significantly reduced (P = .007 and P = .03, respectively) with skin warming around the injection site. DISCUSSION AND CONCLUSIONS: Use of the InsuPad to increase the rate of insulin absorption provides an effective means to achieve better control of postmeal glucose excursions in type 2 diabetic patients receiving premeal injections of rapid-acting insulin analogs.


Asunto(s)
Glucemia/metabolismo , Diabetes Mellitus Tipo 1/tratamiento farmacológico , Hiperglucemia/prevención & control , Hipoglucemiantes/administración & dosificación , Hipoglucemiantes/uso terapéutico , Sistemas de Infusión de Insulina , Insulina/administración & dosificación , Insulina/uso terapéutico , Adolescente , Adulto , Anciano , Estudios Cruzados , Femenino , Prueba de Tolerancia a la Glucosa , Hemoglobina Glucada/análisis , Humanos , Infusiones Subcutáneas , Insulina/sangre , Masculino , Persona de Mediana Edad , Temperatura , Adulto Joven
10.
Rapid Commun Mass Spectrom ; 20(17): 2579-88, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-16897787

RESUMEN

We present newly developed isotope abundance analysis (IAA) methods and software which are used to derive elemental formula information from experimental mass spectral data of molecular ion isotopomeric abundances. The software, using a novel method, can also be used to automatically confirm or reject NIST library search results, thereby significantly improving the confidence level in sample identifications. In the case of IAA confirmation of the NIST library results, sample identification is unambiguous, since the confirmation is achieved by two independent sets of data and analytical methods. In the case of a rejection, such as when the molecule is not included in the library's databases, the IAA software independently provides a list of elemental formulae with declining order of matching to the isotopomeric experimental data, in a similar way to accurate mass measurements with costly instruments. IAA is ideally applicable to gas chromatography/mass spectrometry (GC/MS) (and liquid chromatography/electron ionization mass spectrometry (LC/EI-MS)) with a supersonic molecular beam (SMB) since it requires a trustworthy and highly abundant true molecular ion that is unique to the SMB-MS systems, plus the absence of self chemical ionization and vacuum background noise, again unique features of GC/SMB-MS. The various features of the IAA methods and software are described, their performance is demonstrated with the analysis of experimental GC-SMB-MS data and the IAA concept is compared with accurate mass alternatives. The combination of IAA and GC/SMB-MS is believed to be superior to accurate mass GC/MS in view of the general availability of trustworthy molecular ions for an extended range of compounds.

11.
J Sep Sci ; 29(1): 66-80, 2006 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-16485711

RESUMEN

A novel, simple, and inexpensive approach to sorptive extraction, which we call solvent in silicone tube extraction (SiSTEx), was applied to pesticide residue analysis and its effectiveness and efficiency were evaluated. In SiSTEx, which is a form of open tubular sorptive extraction, a piece of silicone tubing (4 cm long, 1.47 mm ID, 1.96 mm OD in this study) is attached to the cap of a 20 mL glass vial that contains the aqueous sample. The tubing is plugged at the end dangling in the sample solution, and MeCN (e.g., 40 microL) added by syringe to the inner tube volume through a septum in the cap. A stir-bar is used to mix the sample for a certain time (e.g., 60 min), which allows chemicals to partition into the tubing where they diffuse across the silicone and partition into the MeCN. The final MeCN extract is then analyzed for the concentrated analytes. In this study, the SiSTEx approach was evaluated for the analysis of organophosphorus (OP) and organochlorine (OC) pesticides in fruits and vegetables using GC/pulsed flame photometric (PFPD) and halogen specific (XSD) detectors for analysis. The produced samples were initially extracted by a rapid MeCN procedure, and 5 mL of the initial extract was diluted four-fold with water to undergo sorptive extraction for 60 min. The final extract was analyzed by GC/PFPD + XSD for 14 OP and 22 OC pesticides. This simple approach was able to detect 26 of the 36 pesticides at 10 ng/g or less original equivalent sample concentration with average reproducibility of 11% RSD. For those 26 pesticides, a 44-fold lower detection limit on average was achieved in matrix extracts using SiSTEx despite the four-fold dilution with water.

12.
Res Commun Mol Pathol Pharmacol ; 111(1-4): 139-51, 2002.
Artículo en Inglés | MEDLINE | ID: mdl-14632320

RESUMEN

Beta-hydroxy-beta-methylbutyrate, more commonly referred to as HMB, is derived from the amino acid, leucine, and its keto acid, alpha-ketoisocaproate. In several studies combining HMB supplementation and resistance exercise, researchers have concluded that HMB may play an important role in reducing protein degradation and/or increasing recovery of damaged muscle cells. These actions could be advantageous to all individuals participating in exercise programs and improve the lives of many by overcoming weakness or frailty.


Asunto(s)
Músculo Esquelético/efectos de los fármacos , Valeratos/administración & dosificación , Ejercicio Físico , Humanos , Hidrólisis , Proteínas Musculares/metabolismo , Músculo Esquelético/crecimiento & desarrollo , Músculo Esquelético/metabolismo
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