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1.
Med Phys ; 48(1): 19-56, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32392626

RESUMO

BACKGROUND: Geant4 is a Monte Carlo code extensively used in medical physics for a wide range of applications, such as dosimetry, micro- and nanodosimetry, imaging, radiation protection, and nuclear medicine. Geant4 is continuously evolving, so it is crucial to have a system that benchmarks this Monte Carlo code for medical physics against reference data and to perform regression testing. AIMS: To respond to these needs, we developed G4-Med, a benchmarking and regression testing system of Geant4 for medical physics. MATERIALS AND METHODS: G4-Med currently includes 18 tests. They range from the benchmarking of fundamental physics quantities to the testing of Monte Carlo simulation setups typical of medical physics applications. Both electromagnetic and hadronic physics processes and models within the prebuilt Geant4 physics lists are tested. The tests included in G4-Med are executed on the CERN computing infrastructure via the use of the geant-val web application, developed at CERN for Geant4 testing. The physical observables can be compared to reference data for benchmarking and to results of previous Geant4 versions for regression testing purposes. RESULTS: This paper describes the tests included in G4-Med and shows the results derived from the benchmarking of Geant4 10.5 against reference data. DISCUSSION: Our results indicate that the Geant4 electromagnetic physics constructor G4EmStandardPhysics_option4 gives a good agreement with the reference data for all the tests. The QGSP_BIC_HP physics list provided an overall adequate description of the physics involved in hadron therapy, including proton and carbon ion therapy. New tests should be included in the next stage of the project to extend the benchmarking to other physical quantities and application scenarios of interest for medical physics. CONCLUSION: The results presented and discussed in this paper will aid users in tailoring physics lists to their particular application.


Assuntos
Benchmarking , Física , Radiometria , Simulação por Computador , Método de Monte Carlo
2.
Phys Rev Lett ; 125(14): 142701, 2020 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-33064503

RESUMO

The neutron capture cross sections of several unstable nuclides acting as branching points in the s process are crucial for stellar nucleosynthesis studies. The unstable ^{171}Tm (t_{1/2}=1.92 yr) is part of the branching around mass A∼170 but its neutron capture cross section as a function of the neutron energy is not known to date. In this work, following the production for the first time of more than 5 mg of ^{171}Tm at the high-flux reactor Institut Laue-Langevin in France, a sample was produced at the Paul Scherrer Institute in Switzerland. Two complementary experiments were carried out at the neutron time-of-flight facility (n_TOF) at CERN in Switzerland and at the SARAF liquid lithium target facility at Soreq Nuclear Research Center in Israel by time of flight and activation, respectively. The result of the time-of-flight experiment consists of the first ever set of resonance parameters and the corresponding average resonance parameters, allowing us to make an estimation of the Maxwellian-averaged cross sections (MACS) by extrapolation. The activation measurement provides a direct and more precise measurement of the MACS at 30 keV: 384(40) mb, with which the estimation from the n_TOF data agree at the limit of 1 standard deviation. This value is 2.6 times lower than the JEFF-3.3 and ENDF/B-VIII evaluations, 25% lower than that of the Bao et al. compilation, and 1.6 times larger than the value recommended in the KADoNiS (v1) database, based on the only previous experiment. Our result affects the nucleosynthesis at the A∼170 branching, namely, the ^{171}Yb abundance increases in the material lost by asymptotic giant branch stars, providing a better match to the available pre-solar SiC grain measurements compared to the calculations based on the current JEFF-3.3 model-based evaluation.

3.
Radiat Prot Dosimetry ; 180(1-4): 342-345, 2018 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-29036572

RESUMO

33S is a stable isotope of sulphur which is being studied as a potential cooperative target for Boron Neutron Capture Therapy (BNCT) in accelerator-based neutron sources because of its large (n,α) cross section in the epithermal neutron energy range. Previous measurements resolved the resonances with a discrepant description of the lowest-lying and strongest one (at 13.5 keV). However, the evaluations of the major databases do not include resonances, except EAF-2010 which shows smaller values in this range than the experimental data. Furthermore, the glaring lack of data below 10 keV down to thermal (25.3 meV) has motivated a new measurement at n_TOF at CERN in order to cover the whole energy range. The inclusion of this new 33S(n,α) cross section in Monte Carlo simulations provides a more accurate estimation of the deposited kerma rate in tissue due to the presence of 33S. The results of those simulations represent the goal of this work.


Assuntos
Terapia por Captura de Nêutron de Boro/métodos , Isótopos/análise , Nêutrons , Radiometria/métodos , Silício/análise , Radioisótopos de Enxofre/análise , Simulação por Computador , Humanos , Isótopos/química , Método de Monte Carlo , Proteção Radiológica , Radiometria/instrumentação , Dosagem Radioterapêutica , Silício/química , Radioisótopos de Enxofre/química
4.
Appl Radiat Isot ; 88: 203-5, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24491680

RESUMO

(33)S is a stable isotope of sulfur for which the emission of an α-particle is the dominant exit channel for neutron-induced reactions. In this work the enhancement of both the absorbed and the equivalent biologically weighted dose in a BNCT treatment with 13.5keV neutrons, due to the presence of (33)S, has been tested by means of Monte Carlo simulations. The kerma-fluence factors for the ICRU-4 tissue have been calculated using standard weighting factors. The simulations depend crucially on the scarce (33)S(n,α)(30)Si cross-section data. The presence of a high resonance at 13.5keV was established by previous authors providing discrepant resonance parameters. No experimental data below 10keV are available. All of this has motivated a proposal of experiment at the n_TOF facility at CERN. A setup was designed and tested in 2011. Some results of the successful test will be shown. The experiment is scheduled for the period November to December 2012.


Assuntos
Terapia por Captura de Nêutron de Boro/instrumentação , Modelos Estatísticos , Aceleradores de Partículas/instrumentação , Radiometria/instrumentação , Isótopos de Enxofre/química , Isótopos de Enxofre/efeitos da radiação , Absorção de Radiação , Simulação por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Dosagem Radioterapêutica , Espalhamento de Radiação
5.
Neurologia ; 29(2): 76-85, 2014 Mar.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-23601757

RESUMO

INTRODUCTION: Numerous regions of the brain, such as the medial frontal cortex, orbitofrontal cortex, insula, and amygdala, participate in the autonomic control of cardiovascular functions such as heart rate. The degenerative process in frontotemporal dementia (FTD) involves the listed anatomical structures and may therefore produce dysautonomic cardiovascular symptoms. AIM: To observe whether or not non-cardiogenic bradycardia was more frequent in a group of patients with FTD than in subjects with mild cognitive impairment or dementia of a different aetiology. PATIENTS AND METHOD: Once patients with primary cardiac arrhythmia were excluded, we registered the heart rates of 258 patients with cognitive symptoms (36 with FTD, 22 with Alzheimer disease, 23 with vascular dementia, 10 with other dementias, and 167 with non-dementia cognitive impairment). RESULTS: Bradycardia (<60 beats/minute) was significantly more frequent in patients with FTD. This difference remained significant after excluding subjects undergoing treatment with a potentially bradycardic effect. Bradycardia was more prevalent in behavioural FTD cases than in cases of the aphasic variant, and we detected a trend toward higher frequency among patients with more pronounced right hemisphere atrophy. Moreover, mean systolic blood pressure in FTD patients was lower than in other participants, and systolic hypotension (<120 and <100mm Hg) was more prevalent. CONCLUSION: Bradycardia was more frequent in the FTD sample than in other patients with cognitive symptoms. Further investigations will be necessary before we may consider bradycardia to be a sign supporting diagnosis of FTD or its behavioural variant.


Assuntos
Bradicardia/etiologia , Demência Frontotemporal/complicações , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/complicações , Disfunção Cognitiva/complicações , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
6.
Allergol Immunopathol (Madr) ; 41(1): 37-44, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-21940094

RESUMO

BACKGROUND: The diagnosis of anaphylactic reactions due to opiates during anaesthesia can be difficult, since in most cases various drugs may have been administered. Detection of specific IgE to poppy seed might be a marker for sensitisation to opiates in allergic people and heroin-abusers. This study assessed the clinical value of morphine, pholcodine and poppy seed skin-prick and IgE determination in people suffering hypersensitivity reactions during anaesthesia or analgesia and drug-abusers with allergic symptoms. METHODS: We selected heroin abusers and patients who suffered severe reactions during anaesthesia and analgesia from a database of 23,873 patients. The diagnostic yield (sensitivity, specificity and predictive value) of prick and IgE tests in determining opiate allergy was analysed. RESULTS: Overall, 149 patients and 200 controls, mean age 32.9 ± 14.7 years, were included. All patients with positive prick to opiates showed positive prick and IgE to poppy seeds, but not to morphine or pholcodine IgE. Among drug-abusers, 13/42 patients (31%) presented opium hypersensitivity confirmed by challenge tests. Among non-drug abusers, sensitisation to opiates was higher in people allergic to tobacco (25%), P<.001. Prick tests and IgE against poppy seed had a good sensitivity (95.6% and 82.6%, respectively) and specificity (98.5% and 100%, respectively) in the diagnosis of opiate allergy. CONCLUSIONS: Opiates may be significant allergens. Drug-abusers and people sensitised to tobacco are at risk. Both the prick and specific IgE tests efficiently detected sensitisation to opiates. The highest levels were related to more-severe clinical profiles.


Assuntos
Anafilaxia/diagnóstico , Codeína/análogos & derivados , Hipersensibilidade a Drogas/diagnóstico , Imunoglobulina E/sangue , Morfina , Morfolinas , Papaver/imunologia , Transtornos Relacionados ao Uso de Substâncias/complicações , Transtornos Relacionados ao Uso de Substâncias/imunologia , Adolescente , Adulto , Idoso , Anafilaxia/complicações , Estudos de Casos e Controles , Criança , Codeína/efeitos adversos , Codeína/imunologia , Hipersensibilidade a Drogas/complicações , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Morfina/efeitos adversos , Morfina/imunologia , Morfolinas/efeitos adversos , Morfolinas/imunologia , Ópio/administração & dosagem , Papaver/efeitos adversos , Valor Preditivo dos Testes , Sementes , Sensibilidade e Especificidade , Testes Cutâneos , Nicotiana/imunologia , Adulto Jovem
7.
Phys Med Biol ; 55(19): 5833-47, 2010 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-20844337

RESUMO

As carbon ions, at therapeutic energies, penetrate tissue, they undergo inelastic nuclear reactions and give rise to significant yields of secondary fragment fluences. Therefore, an accurate prediction of these fluences resulting from the primary carbon interactions is necessary in the patient's body in order to precisely simulate the spatial dose distribution and the resulting biological effect. In this paper, the performance of nuclear fragmentation models of the Monte Carlo transport codes, FLUKA and GEANT4, in tissue-like media and for an energy regime relevant for therapeutic carbon ions is investigated. The ability of these Monte Carlo codes to reproduce experimental data of charge-changing cross sections and integral and differential yields of secondary charged fragments is evaluated. For the fragment yields, the main focus is on the consideration of experimental approximations and uncertainties such as the energy measurement by time-of-flight. For GEANT4, the hadronic models G4BinaryLightIonReaction and G4QMD are benchmarked together with some recently enhanced de-excitation models. For non-differential quantities, discrepancies of some tens of percent are found for both codes. For differential quantities, even larger deviations are found. Implications of these findings for the therapeutic use of carbon ions are discussed.


Assuntos
Benchmarking/métodos , Carbono/química , Carbono/uso terapêutico , Modelos Teóricos , Método de Monte Carlo
8.
J Appl Microbiol ; 106(3): 886-94, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19191961

RESUMO

AIMS: To investigate the genetic diversity of Pseudomonas savastanoi pv. savastanoi strains and to look whether these strains were distributed to geographical location. METHODS AND RESULTS: Random amplification of polymorphic DNA (RAPD) was used to discriminate between 58 Tunisian strains and 21 strains from various other countries of P. savastanoi pv. savastanoi, the causal agent of olive knot disease. Isolates were separated into three groups by cluster analysis and principal coordinate analysis of RAPD fingerprint data obtained with three primers (OPR-12, OPX-7 and OPX-14). Group 1 contained isolates from the southeast of Tunisia and European strains. Group 2 comprised strains isolated from the north of Tunisia exclusively while group 3 encompassed the majority of isolates obtained from five orchards located in the centre of Tunisia. CONCLUSIONS: The results indicated that isolates of P. savastanoi pv. savastanoi were genetically distinct according to geographic regions. RAPD grouped isolates derived from the same orchard as identical. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first application of RAPD in the delineation of P. savastanoi pv. savastanoi strains.


Assuntos
Olea/microbiologia , Doenças das Plantas/microbiologia , Reação em Cadeia da Polimerase/métodos , Pseudomonas/classificação , Pseudomonas/genética , Técnicas de Tipagem Bacteriana , Impressões Digitais de DNA , DNA Bacteriano/genética , Dados de Sequência Molecular , Pseudomonas/isolamento & purificação , RNA Ribossômico 16S/genética , Tunísia
9.
J Chromatogr A ; 1175(2): 242-8, 2007 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-17996879

RESUMO

A method for the rapid and simultaneous determination of ubiquinone-10 (coenzyme Q10, CoQ(10)) and the reduced form ubiquinol-10 (CoQ(10)H(2)) in human serum by LC-MS-MS with electrospray ionization (ESI) in the positive mode is here proposed. High selective identification and sensitive quantitation of both analytes have been carried out by monitoring the transition from the corresponding precursor ion to the product ion. Prior to the chromatographic analysis, serum samples (100 microl) were subject to a conventional pre-treatment based on protein precipitation, liquid-liquid extraction, evaporation to dryness and reconstitution with 95:5 methanol/hexane (v/v). The overall method has enabled to achieve low detection limits--5.49 and 15.8 ng/ml for CoQ(10) and CoQ(10)H(2), respectively--which were estimated with serum. The accuracy and potential matrix effects have been studied with spiked serum resulting recoveries between 92.82 and 106.97%. The proposed method has been applied to serum samples from healthy middle-age women, in which the CoQ(10)H(2)/CoQ(10) ratio has been used as marker of oxidative stress.


Assuntos
Cromatografia Líquida/métodos , Espectrometria de Massas por Ionização por Electrospray/métodos , Espectrometria de Massas em Tandem/métodos , Ubiquinona/análogos & derivados , Humanos , Oxirredução , Estresse Oxidativo , Ubiquinona/sangue
10.
J Appl Microbiol ; 103(6): 2309-15, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18045415

RESUMO

AIMS: To show the results of the detection of an EU quarantine organism, Xanthomonas axonopodis pv. citri (Xac), in citrus fruits imported from countries where this bacterium is present, using an integrated approach that includes isolation, pathogenicity assays and molecular techniques. METHODS AND RESULTS: Citrus fruits with canker-like symptoms, exported to Spain from South American countries were analysed by several methods. Bacterial isolation, three conventional polymerase chain reaction (PCR) protocols, and real-time PCR with SYBR Green or a TaqMan probe, were compared. Canker-like lesions were disrupted in PBS buffer, and the extract used for bacterial isolation and DNA extraction followed by PCR amplification. Canker lesions, identified by PCR, showed viable bacteria in eleven of fifteen fruit samples. In 16 out of 130 lesions analysed from these samples, Xac was isolated, and pathogenicity on grapefruit leaves confirmed. By real-time PCR, using SYBR green or a Taqman probe, Xac was detected in 58 and 80 lesions respectively. By conventional PCR the bacterium was detected in 39-52 lesions depending on the protocol employed. CONCLUSIONS: An integrated approach for reliable detection of Xac in lesions of fruit samples, employing several techniques and with real-time PCR using a TaqMan probe as the fastest and most sensitive screening method, has been established and validated and is proposed as a useful tool for the analysis of Xac on fresh fruits. SIGNIFICANCE AND IMPACT OF THE STUDY: This work faces up to the real threat of the importation of citrus fruits that can harbour quarantine bacteria and will be useful in diagnostic laboratories for the analysis of commercial fresh fruits from countries where citrus canker is present.


Assuntos
Citrus/microbiologia , Microbiologia de Alimentos , Doenças das Plantas/microbiologia , Xanthomonas axonopodis/isolamento & purificação , Genes Bacterianos , Folhas de Planta/microbiologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Taq Polimerase/genética , Xanthomonas axonopodis/genética
11.
Phytopathology ; 96(3): 313-9, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18944447

RESUMO

ABSTRACT Pseudomonas savastanoi pv. savastanoi causes olive knot disease, which is present in most countries where olive trees are grown. Although the use of cultivars with low susceptibility may be one of the most appropriate methods of disease control, little information is available from inoculation assays, and cultivar susceptibility assessments have been limited to few cultivars. We have evaluated the effects of pathogen virulence, plant age, the dose/response relationship, and the induction of secondary tumors in olive inoculation assays. Most P. savastanoi pv. savastanoi strains evaluated were highly virulent to olive plants, but interactions between cultivars and strains were found. The severity of the disease in a given cultivar was strongly dependent of the pathogen dose applied at the wound sites. Secondary tumors developed in noninoculated wounds following inoculation at another position on the stem, suggesting the migration of the pathogen within olive plants. Proportion and weight of primary knots and the presence of secondary knots were evaluated in 29 olive cultivars inoculated with two pathogen strains at two inoculum doses, allowing us to rate most of the cultivars as having either high, medium, or low susceptibility to olive knot disease. None of the cultivars were immune to the disease.

12.
Arch Biochem Biophys ; 436(1): 32-9, 2005 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-15752706

RESUMO

Arachidonic acid metabolism is modulated during differentiation induced by 1alpha,25(OH)(2)D(3) in HL-60 cells. Antioxidants that affect arachidonic acid metabolism enhance this differentiation program. Ascorbate also enhances differentiation in 1alpha,25(OH)(2)D(3)-induced cells depending on the induction of cAMP. The aim of this work was to study if this cAMP rise depends on modulation of arachidonic acid metabolism by ascorbate. Cyclooxygenase inhibitors, indomethacin and aspirin, increased cAMP levels and also enhanced 1alpha,25(OH)(2)D(3)-induced differentiation in HL-60 cells. Ascorbate did not affect the release of arachidonic acid-derived metabolites but decreased the levels of TXB(2) and PGE(2), suggesting the inhibition of cyclooxygenase. On the other hand, free arachidonic acid increased both cAMP levels and differentiation in the absence or presence of 1alpha,25(OH)(2)D(3). Neither cyclooxygenase inhibitors nor ascorbate modified AA effect. Then, inhibition of cyclooxygenase activity by ascorbate could accumulate free arachidonic acid or other metabolites that increase cAMP levels and enhance differentiation in 1alpha,25(OH)(2)D(3)-induced HL-60 cells.


Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Ácido Araquidônico/metabolismo , Ácido Ascórbico/metabolismo , Diferenciação Celular/fisiologia , AMP Cíclico/metabolismo , Prostaglandina-Endoperóxido Sintases/metabolismo , Vitamina D/análogos & derivados , Vitamina D/farmacologia , Divisão Celular , Células Cultivadas , Inibidores de Ciclo-Oxigenase/farmacologia , Células HL-60 , Humanos , Oxirredução , Vitamina D/metabolismo
15.
J Steroid Biochem Mol Biol ; 89-90(1-5): 209-14, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-15225773

RESUMO

The vdr gene is a candidate for osteoporosis susceptibility, with conflicting results in association studies. We have designed and optimized an individual allele-specific and DNA pooling PCR-based methodology to quantitate BsmI and FokI polymorphisms of the vdr gene and studied single-nucleotide polymorphisms (SNPs) from pooled DNA samples. The allele frequency in DNA pooling experiments has been analyzed by kinetic PCR: quantitative real-time PCR (QRT-PCR). A Spanish cohort of 225 healthy postmenopausal women was studied. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DEXA) and quantitative ultrasound calcaneous densitometry. Allele-specific PCR amplification of BsmI and FokI genes showed full concordance with the PCR-RFLP approach. The prevalence of the three BsmI VDR genotypes was 19.1, 44.9 and 36.0% for BB, Bb and bb, respectively. In the case of the FokI locus, the prevalence of genotypes was 40.4, 48.0 and 11.6% for FF, Ff and ff, respectively. No positive correlation was found between polymorphism and BMD. The DNA pooling procedure was validated. No differences were found in allele frequencies and T-score data obtained using the high throughput DNA pooling approach, as compared to known individual frequencies. In our hands, this is a very useful approach to study quantitative (thus polygenic) traits like osteoporosis susceptibility.


Assuntos
Alelos , DNA/genética , Desoxirribonucleases de Sítio Específico do Tipo II/metabolismo , Frequência do Gene , Polimorfismo Genético , Receptores de Calcitriol/genética , Absorciometria de Fóton , Sequência de Bases , Estudos de Coortes , Primers do DNA , Humanos , Reação em Cadeia da Polimerase Via Transcriptase Reversa
16.
J Steroid Biochem Mol Biol ; 89-90(1-5): 473-7, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-15225823

RESUMO

A new fully automated high-performance liquid chromatography (HPLC) method using 1 ml of serum has been developed for the determination of retinol (Vitamin A), alpha-tocopherol (Vitamin E), 25-hydroxyvitamin D(3) and 24 R,25-hydroxyvitamin D(3). The eluate was monitored with a photodiode-array detector at three wavelengths-namely: 265 nm for Vitamin D(3), 291 nm for Vitamin E and 325 nm for Vitamin A. The detection limits were equal to or lower than 1 ng ml(-1) for all vitamins. The linearity obtained with serum samples (standard addition method) gives correlation coefficients (r(2)) ranging between 0.999 and 0.996 in all cases, with standard deviation of the slope between 3.2 and 1.6%. The repeatability was between 4.0 and 6.0% and the within-laboratory reproducibility was lower than 10% in all cases. The most outstanding features of the present method are its ease of use, its rapidity and fully automation, which enables its use for routine analysis. The time required per sample was 30 min, because the overlapped development of the steps. This method was used for the determination of normality range of these vitamins in healthy people in the 18-80-year-old interval.


Assuntos
Automação , Cromatografia Líquida de Alta Pressão/métodos , Vitaminas/sangue , Humanos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Solubilidade
17.
J Pharm Biomed Anal ; 35(3): 575-82, 2004 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-15137982

RESUMO

A new fully automated method for the determination of metabolites of Vitamin D(3) and Vitamins A and E has been developed. A robotic station for liquid-liquid extraction, connected on line with an automatic system for solid-phase extraction (Prospekt) and a liquid chromatograph were used and the complexity of the overall method was overcome by full automation. The eluate from the chromatograph was monitored by a photodiode-array detector at three wavelengths, namely, 265 nm for Vitamin D(3) metabolites, 291 nm for Vitamin E and 325 nm for Vitamin A-which are the maximum absorption wavelengths for the analytes. The time required per sample analysis was 35 min because of the overlapping development of the steps. The linearity obtained for serum samples (standard addition method) gives correlation coefficients (r(2)) ranging between 0.996 and 0.989, with standard deviation of the slope between 4.0 and 4.9%. The repeatability was between 4.0 and 6.0% and the within-laboratory reproducibility was lower than 10.1% in all cases-both expressed as relative standard deviation-for low concentrations of the analytes, namely, 3 ng/ml for 24,25(OH)(2) dihydroxyvitamin D(3), 10 ng/ml for 25(OH) hydroxyvitamin D(3), 100 ng/ml for Vitamin A and 2 microg/ml for Vitamin E. The method has been validated using a CRM (NIST, SRM968c).


Assuntos
24,25-Di-Hidroxivitamina D 3/sangue , Calcifediol/sangue , Tecnologia Farmacêutica/métodos , Vitamina A/sangue , Vitamina E/sangue , Colecalciferol/metabolismo , Cromatografia Líquida de Alta Pressão/instrumentação , Cromatografia Líquida de Alta Pressão/métodos , Humanos , Tecnologia Farmacêutica/instrumentação
18.
Calcif Tissue Int ; 75(6): 526-32, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15654497

RESUMO

Vitamin D analogs exert a preventative effect on experimental diabetes, but whether or not they are able to halt progress of established diabetes is not yet known. Moreover, it is widely accepted that diabetes may induce osteoporosis, but the efficacy of vitamin D on diabetic osteoporosis is not clear. In order to help clarify these issues, we have tested the efficacy of calcitriol streptozotocin-induced diabetes. Streptozotocin (60 mg/Kg body weight) was injected in 3-month-old Wistar rats, randomly distributed into two groups: vehicle (olive oil) treated diabetic rats (D) and diabetic rats treated with 1.25-(OH)2D3 250 mg, three times a week (DT). Control animals (C) were treated with vehicle alone. The experiment lasted 8 weeks. The histology of the pancreata was evaluated. Blood glucose and calcium and phosphate in serum and urine were measured. Finally, bone mineral density (BMD) of tibia and lumbar vertebrae were evaluated. After 8 weeks, diabetes persisted in 85% of the diabetic rats (D group), but in only 45% of vitamin D-treated group (DT). At the end of the experiment, DT animals were separated into two groups, those still remaining diabetic (DT-NR) and reversed animals (DT-R). Moreover, bone loss was observed in diabetic animals (D), whereas BMD of DT-R rats showed similar values to those of controls (C). Our results suggest that 1.25(OH)2D3 improves diabetes and, as such, may recover BMD in streptozotocin-induced diabetic rats.


Assuntos
Densidade Óssea/efeitos dos fármacos , Calcitriol/metabolismo , Diabetes Mellitus Experimental/metabolismo , Absorciometria de Fóton , Animais , Doenças Ósseas Metabólicas/induzido quimicamente , Reabsorção Óssea/induzido quimicamente , Cálcio/sangue , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/patologia , Feminino , Vértebras Lombares , Pâncreas/patologia , Ratos , Ratos Wistar , Tíbia
19.
Anal Bioanal Chem ; 377(2): 287-92, 2003 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12955389

RESUMO

An almost automated method for the determination of hydroxymetabolites of vitamin D(3) (cholecalciferol) in human serum is reported. The method consists of three steps: 1) a batch liquid-liquid extraction step with 2-propanol and hexane, and drying of the extract and reconstitution with phosphate buffer. 2) A cleanup and preconcentration step based on solid-phase extraction using Prospekt equipment, with CN group cartridges and elution with the chromatographic mobile phase. 3) A chromatographic step for individual separation of the target analytes starting with a 90:10 methanol-water mixture, then a linear gradient to obtain 100% methanol; followed by photometric detection. The method provides a linear range between 1.0 and 100 ng mL(-1) for 24,25-(OH)(2) vitamin D(3) and for 25-(OH)(2) vitamin D(3), and between 1.5 and 100 ng mL(-1) for 1,25-(OH) vitamin D(3), with correlation coefficients ranging between 0.993 and 0.987, repeatability between 1.9% and 4.8% and within-laboratory reproducibility between 2.8% and 8.8%.


Assuntos
Colecalciferol/sangue , Automação , Concentração de Íons de Hidrogênio , Padrões de Referência , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
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