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1.
Cell Death Differ ; 17(7): 1134-40, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19911007

RESUMO

Ergothioneine (ET) is an unusual sulfur-containing derivative of the amino acid, histidine, which is derived exclusively through the diet. Although ET was isolated a century ago, its physiologic function has not been clearly established. Recently, a highly specific transporter for ET (ETT) was identified in mammalian tissues, which explains abundant tissue levels of ET and implies a physiologic role. Using RNA interference, we depleted cells of its transporter. Cells lacking ETT are more susceptible to oxidative stress, resulting in increased mitochondrial DNA damage, protein oxidation and lipid peroxidation. ETT is concentrated in mitochondria, suggesting a specific role in protecting mitochondrial components such as DNA from oxidative damage associated with mitochondrial generation of superoxide. In combating cytotoxic effects of pyrogallol, a known superoxide generator, ET is as potent as glutathione. Because of its dietary origin and the toxicity associated with its depletion, ET may represent a new vitamin whose physiologic roles include antioxidant cytoprotection.


Assuntos
Antioxidantes/farmacologia , Citoproteção/efeitos dos fármacos , Ergotioneína/farmacologia , Dano ao DNA , Células HeLa , Humanos , Peroxidação de Lipídeos , Mitocôndrias/metabolismo , Proteínas de Transporte de Cátions Orgânicos/genética , Proteínas de Transporte de Cátions Orgânicos/metabolismo , Estresse Oxidativo , Interferência de RNA , Espécies Reativas de Oxigênio/metabolismo , Simportadores
2.
Forensic Sci Rev ; 19(1-2): 29-47, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26247282

RESUMO

Since the inception of the drug-testing program in the U.S. Armed Forces in 1982, urine adulteration with the intent to conceal drug use has been a serious problem to forensic scientists. Initially, drug users tried almost anything that was available at the collection sites. Soon they recognized that certain chemicals could be used to destroy some drugs and interfere with the testing procedures. Some drug analytes, in particular morphine and 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid, a metabolite of delta-9-tetrahydrocannabinol, could not be detected in presence of some oxidizing agents. As the use of adulterants increased, specimen validity testing was introduced by the Department of Health and Human Services in 2004. While specific reagents could be used to test nitrite, chromate, and iodine, test procedures for many other oxidizing agents were not available. In an attempt to detect most oxidants, a different approach has been introduced to identify urines adulterated with oxidizing adulterants. In this approach, the oxidizing property of normal urine is compared with that of urine containing oxidizing agents. In the procedure, samples are allowed to interact with excess ferrous (Fe2+) ions and then with chromogenic compounds. In the presence of oxidants, Fe2+ ions with low reduction potential (E0 0.771 V) are immediately oxidized to ferric (Fe3+) ions, which then change the chromogenic compounds to colored chromogens. Specific spectral pattern and intensity are the keys in quantification of oxidants in urine (milliEquivalent/liter, mE/L). The method appeared to be promising in differentiating normal urine from urine adulterated with oxidizing agents. Some oxidizing adulterants in urine are unstable. If reduced, it could be reconverted to the oxidizing agents and tested by the general oxidant test.

3.
J Anal Toxicol ; 25(7): 504-14, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11599592

RESUMO

Heroin is one of the major target drugs in workplace drug-testing programs because of its history of abuse, liability, and continued negative social impact. This study was a comprehensive examination of pharmacokinetics, pharmacodynamics, detection times, opiate immunoassay performance, and urine excretion profiles following single doses of heroin administered to human subjects via smoking and intravenous routes. Studies of the first four components of this investigation were previously published. This article describes the urine excretion profiles. Total morphine (Tmor), free morphine (Fmor), and 6-acetylmorphine (6-AM) were measured by gas chromatography-mass spectrometry (GC-MS) in 920 urine samples collected from 11 male human subjects following single doses of heroin. Eight received intravenous doses of 3, 6, and 12 mg heroin HCI and four smoked 3.5-, 5.2-, 7-, 10.5-, or 13.9-mg doses of heroin (base). In addition, 183 urine-based blind quality-control samples were added to the study set to assess assay performance. Creatinine was also measured in each sample by a colorimetric technique. The parameters studied were not significantly dependent on route of administration. Excretion half-life mean +/- SD for Tmor was 3.11 +/- 0.30 h. Range (median) of peak urine concentrations, time to peak, time to last positive sample for low cutoff (300 ng/mL) and high cutoff (2000 ng/mL) for Tmor following lower doses (< or = 7 mg) were, respectively, 1392-9250 (3620) ng/mL, 1.2-6.2 (2.3) h, 7.4-31.9 (7.4) h, and 0-10.1 (4.3) h. Following higher doses (> 10 mg) they were 2065-29,030 (16,470) ng/mL, 2.3-9.3 (4.5) h, 10.7-53.5 (34.4) h, 2.3-22.3 (8.3) h. Fmor peaked in the same sample as Tmor. Range (median) of peak Fmor concentrations and time to last positive using a cutoff of 100 ng/mL for low and high doses were, respectively, 117-1160 (415) ng/mL, 1.2-10.1 (4.5) h and 150-2580 (1400) ng/mL, 2.3-29.1 (9.3) h. The range (median) of peak urine concentrations for 6-AM was 6.1-568 (124) ng/mL. In general, the first urine void had the peak 6-AM concentration and was the only specimen positive at a 10-ng/mL cutoff. As previously reported urine concentrations varied greatly between subjects and within subjects with time after dosing but were much more predictable when values were reported as amount of drug per unit of creatinine. The range (median) values for percent of heroin excreted into urine as Tmor was 12.8-88.5% (51.0).


Assuntos
Heroína/administração & dosagem , Heroína/farmacocinética , Derivados da Morfina/urina , Morfina/urina , Entorpecentes/farmacocinética , Administração por Inalação , Adulto , Relação Dose-Resposta a Droga , Cromatografia Gasosa-Espectrometria de Massas , Meia-Vida , Heroína/metabolismo , Humanos , Imunoensaio , Injeções Intravenosas , Cinética , Masculino , Morfina/administração & dosagem , Entorpecentes/administração & dosagem , Entorpecentes/metabolismo
4.
J Anal Toxicol ; 25(7): 525-30, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11599595

RESUMO

A gas chromatographic-mass spectrometric procedure for detection of cathinone (Khat) and methcathinone (CAT) in urine was developed. The compounds were detected as 4-carboethoxyhexafluorobutyryl derivatives. Three ions for the drugs and two ions for the internal standards were monitored. The drugs were identified by comparing retention times and ion ratios with that of reference compounds. The concentrations were measured by using amphetamine-d6 as internal standard for cathinone and methamphetamine-d9 as internal standard for methcathinone, and were linear over the range of 25-5000 ng/mL for cathinone and 12.5-5000 ng/mL for methcathinone. The overall recoveries of cathinone and methcathinone were 86 and 78%, respectively. Intrarun and inter-run variations were < 20%. To verify that the drugs are not metabolites of over-the-counter medications, cathinone and methcathinone were tested in urine specimens collected from individuals who ingested phenylpropanolamine and pseudoephedrine. None of the specimens showed the keto-amines as the metabolic products. When the procedure was applied to test 66 amphetamine-immunoassay-positive specimens containing no amphetamine or methamphetamine, two specimens were found positive for cathinone (118 and 3266 ng/mL) and six specimens were found positive for methcathinone (13-91 ng/mL).


Assuntos
Alcaloides/urina , Propiofenonas/urina , Psicotrópicos/urina , Anfetamina/urina , Estimulantes do Sistema Nervoso Central/urina , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Imunoensaio , Sensibilidade e Especificidade , Detecção do Abuso de Substâncias/métodos
5.
Clin Chem ; 47(6): 1040-7, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11375289

RESUMO

BACKGROUND: During the smoking of crack cocaine (COC), methyl ecgonidine (MED) is formed as one of the pyrolysis products. Once in the body, MED is converted to ecgonidine (ED) through several processes that include spontaneous hydrolysis and enzymatic hydrolysis. The presence of MED and/or ED could provide valuable information to help determine antemortem conditions in cases where COC is involved. Our goal was to examine postmortem tissues and fluids for the presence of MED, ED, COC, and benzoylecgonine (BZ). METHODS: Liver, brain, blood, and urine specimens obtained from 15 postmortem cases were extracted using solid-phase extraction, derivatized, and analyzed using gas chromatography-mass spectrometry with selective-ion monitoring. RESULTS: Median concentrations (range) of drugs observed in postmortem liver, brain, blood, and urine were 0 (0-10) ng/g, 7 (0-92) ng/g, 0 (0-42) microg/L, and 62 (0-2030) microg/L, respectively, for MED; 655 (90-3274) ng/g, 22 (0-52) ng/g, 119 (13-773) microg/L, and 456 (109-7452) microg/L, respectively, for ED; 57 (0-503) ng/g, 187 (0-1403) ng/g, 12 (0-88) microg/L, and 1208 (37-28 062) microg/L, respectively, for COC; and 821 (45-4980) ng/g, 524 (46-5153) ng/g, 458 (30-2071) microg/L, and 6768 (917-116 430) microg/L, respectively, for BZ. MED was detected in 12 of 15 postmortem cases. The concentrations were highest in urine compared with liver, brain, and blood. The hydrolysis product ED was detected in all postmortem cases, and the concentrations were substantially higher than MED in all liver, blood, and urine specimens. CONCLUSION: ED may be a more useful indicator of crack COC smoking.


Assuntos
Cocaína/análogos & derivados , Cocaína/análise , Mudanças Depois da Morte , Líquidos Corporais/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Humanos
6.
J Anal Toxicol ; 24(7): 522-9, 2000 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11043654

RESUMO

The Federal Workplace Drug Testing Program changed urine screening and confirmation cutoff concentrations for opiate testing from 300 to 2000 ng/mL in 1998. Morphine was the designated target compound. An additional heroin metabolite, 6-acetylmorphine (6-AM), was added to the testing procedure with a cutoff concentration > or = 10 ng/mL. Testing of 6-AM was required if morphine was positive to assist in medical review. A comparison of the new opiate cutoff concentrations was made with the older cutoff concentration at 300 ng/mL. Six commercial opiate immunoassays, four with a 300-ng/mL cutoff, ONLINE, EMIT, CEDIA and AxSym, and two with 2000-ng/mL cutoffs, ONLINE and EMIT, were selected to test 920 urine samples collected from 11 male human subjects following single doses of heroin. Eight received intravenous doses of 3, 6, and 12 mg heroin HCl and four smoked 3.5-, 5.2-, 10.5-, or 13.9-mg doses of heroin (base). In addition, 183 urine-based blind quality-control specimens were added to the study set to assess linearity, cross-reactivity, and interference. Total morphine, free morphine, and 6-AM were measured in each sample by gas chromatography-mass spectrometry (GC-MS). Linearity, cross-reactivity, and interference results for each immunoassay are described. Detection times, sensitivity, specificity, and efficiency of each assay were determined using data from the specimens collected after heroin administration. Detection times for morphine using the 300-ng/mL cutoff assays was approximately 12 h for low dose and 24 to 48 h for higher doses of heroin. For the two 2000-ng/mL cutoff concentration assays detection time was about 12 h. This was also the detection time for 6-AM by GC-MS. ONLINE had the lowest sensitivity, 60-74%, highest specificity, 98.8-100%, and least interference from a selection of common over-the-counter drugs and opioids. Increasing the cutoff to 2000 ng/mL from 300 ng/mL increased efficiencies of the assays from 72.7 to 82.6% to over 97%.


Assuntos
Heroína/urina , Imunoensaio/instrumentação , Entorpecentes/urina , Detecção do Abuso de Substâncias/instrumentação , Administração por Inalação , Cromatografia Gasosa-Espectrometria de Massas , Heroína/administração & dosagem , Humanos , Injeções Intravenosas , Masculino , Derivados da Morfina/urina , Entorpecentes/administração & dosagem , Distribuição Aleatória , Método Simples-Cego , Fatores de Tempo
7.
J Anal Toxicol ; 24(4): 233-7, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10872568

RESUMO

Pyridinium chlorochromate (PCC) as an adulterant is popular for concealing drug-positive results. When 11-nor-delta9-THC-9-carboxylic acid (THC-acid) in urine was treated with 2 mmol/L of PCC (Cr6+ 104 microg/mL), 58-100% of the THC-acid was lost. The loss increased with decreasing pH and increasing reaction time (0-3 days). Free codeine and free morphine remained unaffected by PCC at pH within the physiological range of the urine (pH 5-7). At lower pH, the loss of free morphine varied from 0 to 100%. Amphetamine, methamphetamine, benzoylecgonine, and PCP remained unaffected by PCC when exposed to the oxidant for three days in urine pH of 3-7. Chromium (VI) from PCC in a urine solution was detected by a color reaction with 1,5-diphenylcarbazide (DPC). When the reagent was added to the urine, an immediate red-violet color appeared. The chromium-DPC complex showed a characteristic absorption peak at wavelength 544 nm with a shoulder at wavelength 575 nm. The ratio of absorption was used to identify the chromium compound. The concentration of chromium (VI) was determined by measuring absorption at wavelength 544 nm and was linear over 0.5-20 microg/mL. The limit of detection of the procedure was 0.37 microg/mL.


Assuntos
Anti-Infecciosos/farmacologia , Cromo/urina , Entorpecentes/urina , Compostos de Piridínio/farmacologia , Detecção do Abuso de Substâncias/métodos , Anti-Infecciosos/farmacocinética , Cromatografia Gasosa , Reações Falso-Negativas , Medicina Legal/métodos , Humanos , Concentração de Íons de Hidrogênio , Compostos de Piridínio/farmacocinética , Urinálise
8.
J Mass Spectrom ; 34(6): 651-60, 1999 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10394630

RESUMO

When cocaine is smoked, methylecgonidine (anhydroecgonine methyl ester) is also consumed as a pyrolytic product. Methylecgonidine, on incubation with human liver homogenate, was metabolized to a stable compound, ecgonidine. The compound was also formed when methylecgonidine was exposed to a urine pH > or = 8.0. Ecgonidine is a zwitterion and highly water soluble. A method was developed to identify ecgonidine quantitatively in urine. After removal of cocaine, benzoylecgonine and methylecgonidine from urine at pH 5.5 +/- 0.5 using a solid-phase extraction (SPE) technique, the pH of the solution was readjusted to 2.0-3.0. The acidic solution reduced the dissociation of the carboxylic acid and improved the lipophilic and cationic character of ecgonidine. The compound was extracted from the solution with the SPE technique with an 89-99% yield. Ecgonidine was then detected as a tert-butyldimethylsilyl derivative by a gas chromatographic/electron ionization mass spectrometric method. Quantitation was linear over the concentration range 7-2000 ng ml-1. Concentrations as low as 7 ng ml-1 can be detected by this procedure. Ecgonidine was detected in > 95% of benzoylecgonine-positive urine specimens from a random drug testing program, indicating smoking as the major route of cocaine administration.


Assuntos
Transtornos Relacionados ao Uso de Cocaína/urina , Cocaína/análogos & derivados , Detecção do Abuso de Substâncias/métodos , Cocaína/urina , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Hidrólise , Indicadores e Reagentes
9.
Clin Chem ; 45(4): 510-9, 1999 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10102911

RESUMO

BACKGROUND: Both the Department of Defense (DoD) and the Department of Health and Human Services (DHHS) currently require two confirmation tests to verify use of heroin, one test for total morphine and a separate test for 6-acetylmorphine (6-AM). Our aim was to determine appropriate free-codeine, free-morphine, and 6-AM cutoff concentrations that could be substituted for total-morphine, total-codeine, and 6-AM cutoff concentrations and to develop a less labor-intensive method for measuring codeine, morphine, and 6-AM. METHODS: Urine samples containing opiates were extracted, derivatized, and analyzed using gas chromatography-mass spectrometry with selective ion monitoring. RESULTS: The limits of detection for codeine, morphine, and 6-AM were 6, 5, and 0.5 microg/L, respectively. Recoveries were >90%. Quantification was linear over the concentration range of 6-1000 microg/L for codeine, 5-5000 microg/L for morphine, and 0.5-800 microg/L for 6-AM. Cutoff concentrations for confirmation of opiates were 100, 100, and 10 microg/L for free codeine, free morphine, and 6-AM. CONCLUSION: The proposed cutoff concentrations for free morphine and 6-AM provide better detection windows for morphine and heroin use than the cutoff concentrations for total morphine and 6-AM used at present. Detection of free codeine, instead of total codeine, simplifies interpretation of codeine use. The single-extraction method enables simultaneous, less labor-intensive analysis of morphine, codeine, and 6-AM.


Assuntos
Codeína/urina , Derivados da Morfina/urina , Morfina/urina , Detecção do Abuso de Substâncias/métodos , Cromatografia Gasosa-Espectrometria de Massas , Dependência de Heroína/urina , Humanos , Radioimunoensaio , Valores de Referência , Sensibilidade e Especificidade
10.
Forensic Sci Rev ; 11(2): 157-74, 1999 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26255904

RESUMO

LSD is a psychoactive semisynthetic ergot alkaloid. It is so potent that a small dose (≊25 µg) may produce a profound hallucinogenic effect. The compound is a controlled substance under the US code of regulations. One of the major adverse effects of LSD is the "flashback" or spontaneous recurrences of hallucinogenic effects that may occur months to years after cessation of the drug. The major concern of LSD abuse is the long duration of action and fatal accidents and suicides during the state of intoxication. Because LSD metabolizes to a number of compounds and detection methods for these compounds in a large number of samples are not well established, most of the methods are aimed at identifying unchanged LSD in urine. After initial screening by an immunoassay method, the presence of LSD in urine is confirmed by a gas chromatographic-mass spectrometric (GC-MS) method. The immunoassay techniques are simple and cost-effective. In confirmation, selective extraction is preferred because it allows detection of the compound at concentrations as low as 50 pg/mL. Recent methods for detection of an LSD metabolite, 2-oxo-3-hydroxy-LSD, by liquid chromatography-mass spectrometry appeared to be promising in some forensic investigations.

11.
J Pers Assess ; 70(1): 183-9, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9615430

RESUMO

In this study, we investigated MCMI-II profile differences in a sample of 65 Black and 164 White psychiatric inpatients. A multivariate analysis of variance (MANOVA) yielded a significant multivariate effect associated with race, with Black patients scoring significantly higher on the Histrionic, Narcissistic, Paranoid, Drug Dependent and Delusional Disorder scales. A second MANOVA was conducted on these 5 scales with a smaller sample of 46 Black and 46 White patients, who were matched for primary Axis I discharge diagnosis and matched for substance abuse comorbidity. This MANOVA did not yield a significant multivariate effect associated with race, and scale differences were attenuated.


Assuntos
Negro ou Afro-Americano/psicologia , Transtornos Mentais/diagnóstico , Inventário de Personalidade , Psicometria , População Branca/psicologia , Adulto , Análise de Variância , Humanos , Masculino , Análise Multivariada , Reprodutibilidade dos Testes , Estudos Retrospectivos , Estados Unidos
12.
Psychol Rep ; 82(2): 563-9, 1998 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9621730

RESUMO

49 prospective clients from a midwestern urban community, who sought counseling at a university training clinic, completed the Self-expressiveness in the Family Questionnaire and the 20-item Toronto Alexithymia Scale. As predicted, the positive self-expressiveness scores were significantly negatively correlated -.52 with scores on alexithymia, and the negative self-expressiveness scores were significantly positively correlated .34 with alexithymia. These results support the premise that mental health clients' self-reported lack of positive expressiveness and abundance of negative expressiveness within their family context may be attributes associated with their tendency to be alexithymic.


Assuntos
Sintomas Afetivos/psicologia , Emoções Manifestas , Saúde da Família , Adulto , Emoções Manifestas/classificação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Análise de Regressão
13.
Biol Chem ; 379(4-5): 579-82, 1998.
Artigo em Inglês | MEDLINE | ID: mdl-9628359

RESUMO

We have developed a new strategy with a very tight control for the expression of cloned genes. The system employed here is the T7 promoter-based expression system in which transcription activator protein C of bacteriophage Mu (Mu C) has been cloned to serve as a repressor in the regulatory circuit. The system also includes pLysE, which encodes T7 lysozyme, an inhibitor of T7 RNA polymerase. This ensures tight regulation of cloned genes in the uninduced state. Upon induction, the expressed Mu C protein binds to its cognate site thereby repressing lys transcription driven by the tet promoter. In order to evaluate the tight control achieved in the system, and to check leaky expression, if any, we have cloned the gene for the SmaI restriction endonuclease without its cognate methylase. For this purpose, a dicistronic unit was constructed by cloning the smaIR gene downstream of the Mu C gene. SmaI expression was observed only in the induced cell extracts, demonstrating a tight control. The system could be used to express the genes of other cloned restriction enzymes and has the potential for general applications.


Assuntos
Desoxirribonucleases de Sítio Específico do Tipo II/genética , Expressão Gênica , Vetores Genéticos , Serratia marcescens/enzimologia , Proteínas Virais , Bacteriófago T7/genética , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos , Proteínas de Ligação a DNA/genética , Regiões Promotoras Genéticas , Proteínas Recombinantes de Fusão/genética , Serratia marcescens/genética , Transativadores/genética
14.
Clin Chem ; 44(2): 287-92, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9474026

RESUMO

A sensitive method is described to detect isolysergic acid diethylamide (iso-LSD) in urine. The compound was extracted from urine and converted to a C-8 carbanion by sodium ethoxide in ethanol. Protonation of the carbanion by water selectively produced LSD. The conversion of iso-LSD to LSD was almost quantitative (98%). The product was purified by solid-phase fractionation and acid-base separation techniques. The trimethylsilyl derivative of LSD was detected by a gas chromatography-mass spectrometry method. The overall recovery of the procedure was approximately 69%. Quantification of iso-LSD was linear over the concentration range 50-2000 ng/L. In specimen analysis, iso-LSD was detected when the LSD concentration was below the limit of the detection (50 ng/L) of the procedure. Because iso-LSD is a byproduct of illicit preparation of LSD, presence of iso-LSD in urine is an indication of LSD use.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Dietilamida do Ácido Lisérgico/urina , Etanol/análogos & derivados , Etanol/farmacologia , Humanos , Isomerismo , Estrutura Molecular , Sensibilidade e Especificidade , Transtornos Relacionados ao Uso de Substâncias/urina , Fatores de Tempo
15.
Protein Eng ; 10(8): 935-41, 1997 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-9415443

RESUMO

A sensitive dimerization assay for DNA binding proteins has been developed using gene fusion technology. For this purpose, we have engineered a gene fusion using protein A gene of Staphylococcus aureus and C gene, the late gene transactivator of bacteriophage Mu. The C gene was fused to the 3' end of the gene for protein A to generate an A-C fusion. The overexpressed fusion protein was purified in a single step using immunoglobulin affinity chromatography. Purified fusion protein exhibits DNA binding activity as demonstrated by electrophoretic mobility shift assays. When the fusion protein A-C was mixed with C and analyzed for DNA binding, in addition to C and A-C specific complexes, a single intermediate complex comprising of a heterodimer of C and A-C fusion proteins was observed. Further, the protein A moiety in the fusion protein A-C does not contribute to DNA binding as demonstrated by proteolytic cleavage and circular dichroism (CD) analysis. The assay has also been applied to analyze the DNA binding domain of C protein by generating fusions between protein A and N- and C-terminal deletion mutants of C. The results indicate a role for the region towards the carboxy terminal of the protein in DNA binding. The general applicability of this method is discussed.


Assuntos
Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Transativadores/química , Transativadores/metabolismo , Proteínas Virais/química , Proteínas Virais/metabolismo , Sequência de Aminoácidos , Fusão Gênica Artificial , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos , Sítios de Ligação , Cromatografia Líquida , Dicroísmo Circular , DNA/metabolismo , Proteínas de Ligação a DNA/genética , Dimerização , Escherichia coli/genética , Sequências Hélice-Volta-Hélice/genética , Dados de Sequência Molecular , Mutação , Plasmídeos/genética , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/isolamento & purificação , Proteínas Recombinantes de Fusão/metabolismo , Análise de Sequência , Deleção de Sequência/genética , Proteína Estafilocócica A , Relação Estrutura-Atividade , Transativadores/genética , Tripsina/metabolismo , Proteínas Virais/genética
16.
Gene ; 190(1): 11-5, 1997 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-9185843

RESUMO

We had earlier overproduced the transcription activator protein C of bacteriophage Mu in a phage-T7 expression system. Although we achieved a high level of overproduction, the expression was not consistent. This could be due to the leaky expression of T7 RNA polymerase in the uninduced state. Introduction of pLysS, a plasmid encoding T7 lysozyme, a natural inhibitor of T7 RNA polymerase, resulted in consistent, but extremely low production of the C protein. To overcome this problem, we have devised an artificial regulatory circuit to obtain stabilised, consistent overproduction of C protein. The C-binding site was cloned downstream from the transcription start point of T7 lys. Upon induction, the C protein produced binds to its site with a very high affinity, possibly acting as a transcriptional roadblock for lys. This would overcome the inhibitory effect of T7 lysozyme on T7 RNA polymerase.


Assuntos
Bacteriófago T7/genética , Proteínas de Ligação a DNA/genética , Bacteriófago T7/enzimologia , Sítios de Ligação , Clonagem Molecular , RNA Polimerases Dirigidas por DNA/genética , Muramidase/genética , Muramidase/metabolismo , Plasmídeos , Proteína C/metabolismo , Proteínas Virais
17.
Planta Med ; 62(6): 544-7, 1996 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9000887

RESUMO

In addition to codeine and morphine, three more compounds: narcotine (noscapine), papaverine, and thebaine were found in Indian and Netherlands poppy seeds (Papaver somniferum L). The compounds were detected by a GC/MS technique and the identities were confirmed by comparing retention times and ion ratios with the known references. The concentrations of codeine, morphine, thebaine, papaverine, and narcotine were 44, 167, 41, 67, and 230 micrograms/g in Indian poppy seeds, and were 1.8, 39, 1.0, 0.17, 0.84 micrograms/g in Netherlands poppy seeds, respectively. Because these compounds may be urinary products after poppy seed consumption, the lowest detectable concentrations of codeine, morphine, thebaine, papaverine, and narcotine in urine are of interest and were found to be 4, 4, 5, 0.4, and 4 ng/ml, respectively. The detection of urinary narcotine, papaverine, or thebaine may be utilized to differentiate poppy seed consumption from illicit codeine, morphine, or heroin use.


Assuntos
Noscapina/análise , Papaver/química , Papaverina/análise , Plantas Medicinais , Tebaína/análise , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Noscapina/urina , Papaverina/urina , Sementes/química , Detecção do Abuso de Substâncias , Tebaína/urina
18.
J Anal Toxicol ; 20(6): 506-8, 1996 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8889689

RESUMO

A simple procedure was developed to derivatize benzoylecgonine extracted from urine for subsequent confirmation by gas chromatography-mass spectrometry. The compound was esterified with dimethylformamide-dipropylacetal (DMF-DPA) or dimethylformamide-diisopropylacetal (DMF-DIPA) to the corresponding propyl and isopropyl esters. The optimum reaction condition was found to be heating the reaction mixture in the presence of pyridine at 100 degrees C for 30 min. The procedure is a one-step esterification followed by evaporation of excess reagents. When benzoylecgonine was extracted from urine using a solid-phase extraction technique and derivatized with this procedure, the compound was detected at a level as low as 10 ng/mL. Quantitation was linear over the concentration range 10-8000 ng/mL.


Assuntos
Acetais/química , Cocaína/análogos & derivados , Dimetilformamida/química , Piridinas/química , Cocaína/química , Cocaína/urina , Esterificação , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Estereoisomerismo
19.
J Anal Toxicol ; 18(6): 331-6, 1994 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-7823540

RESUMO

During periodate degradation of interfering ephedrine, pseudoephedrine, and phenylpropanolamine in the extraction of methamphetamine from urine, it was observed that a small amount of methamphetamine was demethylated to amphetamine. although all three interfering phenylpropanolamines could be degraded by periodate at pH 5.2 and above, this periodate-mediated transformation of methamphetamine to amphetamine was observed only at pH 9.1 and above. Therefore, to avoid this transformation, a pH of 6.2 was used for the oxidative degradation of phenylpropanolamines. The excess periodate was then reduced with thiosulfate or ascorbic acid prior to the extraction of methamphetamine using a basic pH.


Assuntos
Anfetamina/urina , Artefatos , Metanfetamina/urina , Ácido Periódico , Efedrina , Humanos , Metanfetamina/química , Oxirredução , Fenilpropanolamina , Urinálise/métodos
20.
J Anal Toxicol ; 17(6): 378-80, 1993 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8271786

RESUMO

Benzoylecgonine, 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (THC-acid), phencyclidine, codeine, morphine, amphetamine, methamphetamine, and lysergic acid diethylamide were dissolved in urine, stored frozen in plastic tubes at -16 to -18 degrees C, defrosted, transferred to other tubes, and analyzed by gas chromatography/mass spectrometry (GC/MS); no significant loss of compound was observed, except for THC-acid, which showed an average loss of 11%, ranging from 0 to 34% of the total concentration. The loss is attributed to the decrease in solubility of the compound and to adherence to the side of the container during freezing.


Assuntos
Congelamento , Drogas Ilícitas/urina , Detecção do Abuso de Substâncias/métodos , Humanos
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