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1.
Anal Bioanal Chem ; 415(5): 809-821, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36507958

RESUMO

The US National Institute of Standards and Technology (NIST) developed a Standard Reference Material® (SRM®) 3949 Folate Vitamers in Frozen Human Serum to replace SRM 1955 Homocysteine and Folate in Human Serum. The presence of increased endogenous levels of folic acid and 5-methyltetrahydrofolate (5mTHF) in SRM 3949, enhanced folate stability via addition of ascorbic acid, and inclusion of values for additional minor folates are improvements over SRM 1955 that should better serve the clinical folate measurement community. The new SRM contains folates at three levels. To produce SRM 3949, pilot sera were collected from 15 individual donors, 5 of whom were given a 400-µg folic acid supplement 1 h prior to blood draw to increase serum levels of 5mTHF and folic acid for the high-level material. To stabilize the folates, 0.5% (mass concentration) ascorbic acid was added as soon as possible after preparation of serum. These pilot sera were screened for five folates plus the pyrazino-s-triazine derivative of 4-α-hydroxy-5-methyltetrahydrofolate (MeFox) at the US Centers for Disease Control and Prevention (CDC) by isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS). Based on these results, a blending protocol was specified to obtain the three desired folate concentrations for SRM 3949. ID-LC-MS/MS analysis at the CDC and NIST was utilized to assign values for folic acid and 5mTHF, as well as several minor folates.


Assuntos
Ácido Fólico , Espectrometria de Massas em Tandem , Humanos , Ácido Fólico/análise , Cromatografia Líquida/métodos , Espectrometria de Massas em Tandem/métodos , Padrões de Referência , Ácido Ascórbico
2.
Anal Chem ; 89(19): 10461-10467, 2017 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-28930436

RESUMO

A new tobacco filler Standard Reference Material (SRM) has been issued by the National Institute of Standards and Technology (NIST) in September 2016 with certified and reference mass fraction values for nicotine, N-nitrosonornicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, and volatiles. The constituents have been determined by multiple analytical methods with measurements at NIST and at the Centers for Disease Control and Prevention, and with confirmatory measurements by commercial laboratories. This effort highlights the development of the first SRM for reduced nicotine and reduced tobacco-specific nitrosamines with certified values for composition.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Espectrometria de Massas em Tandem/métodos , Produtos do Tabaco/análise , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida de Alta Pressão/normas , Congelamento , Cromatografia Gasosa-Espectrometria de Massas/normas , Nicotina/análise , Nicotina/normas , Nitrosaminas/análise , Nitrosaminas/normas , Transição de Fase , Padrões de Referência , Espectrometria de Massas em Tandem/normas , Produtos do Tabaco/normas , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/normas
3.
Biometals ; 29(6): 1005-1018, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27649965

RESUMO

Electrical responses of olfactory sensory neurons to odorants were examined in the presence of zinc nanoparticles of various sizes and degrees of oxidation. The zinc nanoparticles were prepared by the underwater electrical discharge method and analyzed by atomic force microscopy and X-ray photoelectron spectroscopy. Small (1.2 ± 0.3 nm) zinc nanoparticles significantly enhanced electrical responses of olfactory neurons to odorants. After oxidation, however, these small zinc nanoparticles were no longer capable of enhancing olfactory responses. Larger zinc oxide nanoparticles (15 nm and 70 nm) also did not modulate responses to odorants. Neither zinc nor zinc oxide nanoparticles produced olfactory responses when added without odorants. The enhancement of odorant responses by small zinc nanoparticles was explained by the creation of olfactory receptor dimers initiated by small zinc nanoparticles. The results of this work will clarify the mechanisms for the initial events in olfaction, as well as to provide new ways to alleviate anosmia related to the loss of olfactory receptors.


Assuntos
Nanopartículas Metálicas/química , Odorantes , Neurônios Receptores Olfatórios/efeitos dos fármacos , Zinco/química , Zinco/farmacologia , Animais , Eletrofisiologia/métodos , Masculino , Microscopia de Força Atômica , Microscopia Eletrônica de Transmissão , Neurônios Receptores Olfatórios/fisiologia , Espectroscopia Fotoeletrônica , Ratos Sprague-Dawley , Receptores Odorantes/química , Óxido de Zinco/química , Óxido de Zinco/farmacologia
4.
Microchem J ; 110: 263-265, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30976130

RESUMO

A method is developed to determine the amount of organic and inorganic phosphorus in an inorganic polymer (hydroxyapatite (HAP)) modified with an organic phosphorus - containing complexant. The simplicity and precision of the vanadate method has made it useful for measuring the total phosphorus content in phosphorus - containing organic polymers that are first digested in concentrated sulfuric acid. However, it can be important to quantify the organic and inorganic phosphorus capacities in modified (hybrid) polymers and this method does not distinguish between the two. In the current report, HAP was modified with 1-hydroxyethane-1,1-diphosphonic acid (HEDP) and a method developed to give the respective phosphorus capacities. HAP was contacted with HEDP for 17 h, 28 h, 56 h, 84 h, 112 h, and 140 h. By combining results from the sulfuric acid digestion of the modified polymer with those from a separate digestion in HCl, it was determined that there was a monotonic increase in the organic phosphorus capacity from 0.04 to 2.44 mmol / g, and a decrease in the inorganic phosphorus capacity from 4.68 to 2.54 mmol / g.

5.
PLoS One ; 12(12): e0189273, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29261701

RESUMO

Olfactory responses are intensely enhanced with the addition of endogenous and engineered primarily-elemental small zinc nanoparticles (NPs). With aging, oxidation of these Zn nanoparticles eliminated the observed enhancement. The design of a polyethylene glycol coating to meet storage requirements of engineered zinc nanoparticles is evaluated to achieve maximal olfactory benefit. The zinc nanoparticles were covered with 1000 g/mol or 400 g/mol molecular weight polyethylene glycol (PEG). Non-PEGylated and PEGylated zinc nanoparticles were tested by electroolfactogram with isolated rat olfactory epithelium and odorant responses evoked by the mixture of eugenol, ethyl butyrate and (±) carvone after storage at 278 K (5 oC), 303 K (30 oC) and 323 K (50 oC). The particles were analyzed by atomic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and laser Doppler velocimetry. Our data indicate that stored ZnPEG400 nanoparticles maintain physiologically-consistent olfactory enhancement for over 300 days. These engineered Nanoparticles support future applications in olfactory research, sensitive detection, and medicine.


Assuntos
Nanopartículas Metálicas/química , Odorantes , Mucosa Olfatória/efeitos dos fármacos , Polietilenoglicóis/química , Zinco/química , Microscopia de Força Atômica , Microscopia Eletrônica de Transmissão , Espectroscopia Fotoeletrônica
6.
Int J Nanomedicine ; 11: 1567-76, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27143879

RESUMO

BACKGROUND: Small metal nanoparticles obtained from animal blood were observed to be toxic to cultured cancer cells, whereas noncancerous cells were much less affected. In this work, engineered zinc and copper metal nanoparticles were produced from bulk metal rods by an underwater high-voltage discharge method. The metal nanoparticles were characterized by atomic force microscopy and X-ray photoelectron spectroscopy. The metal nanoparticles, with estimated diameters of 1 nm-2 nm, were determined to be more than 85% nonoxidized. A cell viability assay and high-resolution light microscopy showed that exposure of RG2, cultured rat brain glioma cancer cells, to the zinc and copper nanoparticles resulted in cell morphological changes, including decreased cell adherence, shrinking/rounding, nuclear condensation, and budding from cell bodies. The metal-induced cell injuries were similar to the effects of staurosporine, an active apoptotic reagent. The viability experiments conducted for zinc and copper yielded values of dissociation constants of 0.22 ± 0.08 nmol/L (standard error [SE]) and 0.12 ± 0.02 nmol/L (SE), respectively. The noncancerous astrocytes were not affected at the same conditions. Because metal nanoparticles were lethal to the cancer cells at sub-nanomolar concentrations, they are potentially important as nanomedicine. PURPOSE: Lethal concentrations of synthetic metal nanoparticles reported in the literature are a few orders of magnitude higher than the natural, blood-isolated metal nanoparticles; therefore, in this work, engineered metal nanoparticles were examined to mimic the properties of endogenous metal nanoparticles. MATERIALS AND METHODS: RG2, rat brain glioma cells CTX TNA2 brain rat astrocytes, obtained from the American Type Culture Collection, high-voltage discharge, atomic force microscope, X-ray photoelectron spectroscopy, high-resolution light microscopy, zeta potential measurements, and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay were used in this work. RESULTS: Engineered zinc and copper metal nanoparticles of size 1 nm-2 nm were lethal to cultured RG2 glioma cancer cells. Cell death was confirmed by MTT assay, showing that the relative viability of RG2 glioma cells is reduced in a dose-dependent manner at sub-nanomolar concentrations of the nanoparticles. The noncancerous astrocytes were not affected at the same conditions. CONCLUSION: The engineered and characterized zinc and copper nanoparticles are potentially significant as biomedicine.


Assuntos
Neoplasias Encefálicas/tratamento farmacológico , Cobre/química , Glioma/tratamento farmacológico , Nanopartículas Metálicas/administração & dosagem , Nanomedicina , Zinco/química , Animais , Encéfalo/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Nanopartículas Metálicas/química , Ratos , Células Tumorais Cultivadas
7.
Lab Anim (NY) ; 34(3): 39-41, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15735638

RESUMO

The gray short-tailed opossum has been a subject in behavioral and biomedical studies for the last quarter century, but researchers know little about its preferred diet. The authors describe a study designed to determine food preferences of this species for the purpose of identifying suitable rewards to be used in behavioral studies.


Assuntos
Dieta , Preferências Alimentares/fisiologia , Gambás/fisiologia , Animais , Feminino , Masculino , Gravação em Vídeo
8.
Ind Eng Chem Res ; 54(2): 585-596, 2015 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-25678741

RESUMO

Hydroxyapatite (HAP) was modified with 1-hydroxyethane-1,1-diphosphonic acid (HEDP), and its effect on divalent metal ion binding was determined. HAP was synthesized from calcium hydroxide and phosphoric acid. After calcination, it was modified with HEDP, and the influence of time and temperature on the modification was investigated. HEDP incorporation increased as its initial solution concentration increased from 0.01 to 0.50 M. Unmodified and modified HAP were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and specific surface area analysis. Ca/P ratios, acid capacities, and phosphorus elemental analyses gave the effect of modification on composition and surface characteristics. A high reaction temperature produced new phosphonate bands at 993, 1082, and 1144 cm-1 that indicated the presence of HEDP. HAP modification at a high temperature-long reaction time had the highest HEDP loading and gave the sharpest XRD peaks. The emergence of new HAP-HEDP strands was observed in SEM images for treated samples while EDS showed high phosphorus contents in these strands. Modified HAP had a high acid capacity from the additional P-OH groups in HEDP. The P(O)OH groups maintain their ability to bind metal ions within the HAP matrix: contacting the modified HAP with 10-4 N nitrate solutions of five transition metal ions gives an affinity sequence of Pb(II) > Cd(II) > Zn(II) > Ni(II) > Cu(II). This result is comparable to that of commercially available di(2-ethylhexyl)phosphoric acid, a common solvent extractant, and the trend is consistent with the Misono softness parameter of metal ion polarizabilities.

9.
Nutr Metab (Lond) ; 2(1): 6, 2005 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-15725360

RESUMO

Although feeding deficits have been reported in snakes and lizards following vomeronasal system disruption, no deficit has been previously reported in a mammal. We tested gray short-tailed opossums with items from four different food categories prior to occluding access to the vomeronasal organ. Preoperatively, opossums preferred meat to fruit or vegetables. Following occlusion of the nasopalatine canal, but not after control treatment, opossums failed to demonstrate food preferences.

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