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At least 235 records · Page 13Linked to original sources
PubMed2002

Identification of dehydroepiandrosterone metabolites formed from human prostate homogenate using liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry.

The identification of the in vitro metabolites of dehydroepiandrosterone formed from human prostate homogenate was investigated by hyphenated techniques using the stable-isotope dilution method. A mixture of dehydroepiandrosterone and [2H4]dehydroepiandrosterone was incubated with hypertrophied human prostate tissue homogenate in the presence of NAD, NADH and NADPH. The metabolites were extracted with AcOEt-hexane, purified by solid-phase extraction, and then analyzed by LC-atmospheric pressure chemical ionization MS and/or GC-MS. Androst-5-ene-3beta,17beta-diol (major product), androst-4-ene-3,17-dione, testosterone, 5alpha-dihydrotestosterone, androsterone, and 7alpha-hydroxydehydroepiandrosterone were identified in comparison with authentic samples based on their chromatographic behavior and mass spectra.

Chromatography, Gas↗
PubMed2000

Studies on neurosteroids. Part XIII. Characterization of catechol estrogens in rat brains using liquid chromatography-mass spectrometry-mass spectrometry.

The existence of catechol estrogens in rat brains was clarified using liquid chromatography-atmospheric pressure chemical ionization-ion trap-mass spectrometry-mass spectrometry (LC-APCI-MS2). The catechol estrogens were extracted in the presence of ascorbic acid and then derivatized to acetates with acetic anhydride and pyridine. After a successive purification with silica gel mini-column chromatography, reversed-phase solid-phase extraction and preparative HPLC, the obtained fractions containing the catechol estrogen acetates were subjected to LC-APCI-MS2. 2-Hydroxyestrone, 2-hydroxyestradiol and their 4-hydroxy isomers were identified as acetates by comparison with authentic samples based on their chromatographic behavior and mass spectral data. The derivatization to acetate was useful for the treatment of labile catechol estrogens.

Acetates↗
PubMed2003

Electrospray ionization mass spectrometry coupled to liquid chromatography for detection of cisplatin and its hydrated complexes.

Electrospray ionization mass spectrometry (ESI-MS) coupled to liquid chromatography (LC) has been applied to investigate cisplatin and its hydrated complexes. Three hydrolysis products were identified following incubation of cisplatin in aqueous solution: monohydrated species, dihydrated species and the hydroxo-bridged dimer, each of which exhibited characteristic mass spectrometric behavior. The technique was employed to investigate the time- and pH-dependent hydrolysis of cisplatin in aqueous solution. The results have demonstrated that LC/ESI-MS is a powerful technique for the analysis of Pt(II) complexes and for monitoring their hydrolysis reactions.

Antineoplastic Agents↗
PubMed1997

Profiling degradants of paclitaxel using liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry substructural techniques.

A rapid and systematic strategy based on liquid chromatography-mass spectrometry (LC-MS) profiling and liquid chromatography-tandem mass spectrometry (LC-MS-MS) substructural techniques was utilized to elucidate the degradation products of paclitaxel, the active ingredient in Taxol. This strategy integrates, in a single instrumental approach, analytical HPLC, UV detection, full-scan electrospray MS, and MS-MS to rapidly and accurately elucidate structures of impurities and degradants. In these studies, degradants induced by acid, base, peroxide, and light were profiled using LC-MS and LC-MS-MS methodologies resulting in an LC-MS degradant database which includes information on molecular structures, chromatographic behavior, molecular mass, and MS-MS substructural information. The stressing conditions which may cause drug degradation are utilized to validate the analytical monitoring methods and serve as predictive tools for future formulation and packaging studies. Degradation products formed upon exposure to basic conditions included baccatin III, paclitaxel sidechain methyl ester, 10-deacetylpaclitaxel, and 7-epipaclitaxel. Degradation products formed upon exposure to acidic conditions included 10-deacetylpaclitaxel and the oxetane ring opened product. Treatment with hydrogen peroxide produced only 10-deacetylpaclitaxel. Exposure to high intensity ligh produced a number of degradants. The most abundant photodegradant of paclitaxel corresponded to an isomer which contains a C3-C11 bridge. These methodologies are applicable at any stage of the drug product cycle from discovery through development. This library of paclitaxel degradants provides a foundation for future development work regarding product monitoring, as well as use as a diagnostic tool for new degradation products.

Antineoplastic Agents, Phytogenic↗
PubMed1982

Bile acids. LXVII. The major bile acids of Varanus monitor.

The major bile acids of gall bladder bile of Varanus monitor have been separated by thin-layer chromatography and shown to be derivatives of taurine. After alkaline hydrolysis, the free acids were separated by thin-layer and partition chromatography. Identification or characterization of the free acids was facilitated by gas-liquid chromatography and gas-liquid chromatography-mass spectometry of the methyl esters or methyl ester-trimethylsilyl ethers. About 13% of the total bile acids was represented by the C24 acids cholic, deoxycholic, allocholic, chenodeoxycholic, and 12-oxo-3 alpha-hydroxy-5 beta-cholanic acids, of which cholic acid constituted about 50%. The remainder of the bile acids consisted of eight C27 acids of which varanic acid was the major constituent; an isomer of varanic acid and 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestanoic acid were also identified. By chromatographic behavior and mass spectral fragmentation, the structures of four C27 acids with unsaturated side chains were elucidated as follows: 3 alpha, 7 alpha-dihydroxy-5 beta-cholest-23-enoic, 3 alpha, 7 alpha-dihydroxy-5 beta-cholest-24-enoic, 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholest-23-enoic, and 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholest-24-enoic acids. Similarly, the structure of the 12-deoxy analog of varanic acid, 3 alpha, 7 alpha, 24 xi-trihydroxy-5 beta-cholestanoic acid, was suggested for the component that constituted 7% of the total.

Animals↗
PubMed2006

The mass media are an important context for adolescents' sexual behavior.

PURPOSE: This study compared influences from the mass media (television, music, movies, magazines) on adolescents' sexual intentions and behaviors to other socialization contexts, including family, religion, school, and peers. METHODS: A sample of 1011 Black and White adolescents from 14 middle schools in the Southeastern United States completed linked mail surveys about their media use and in-home Audio-CASI interviews about their sexual intentions and behaviors. Analysis of the sexual content in 264 media vehicles used by respondents was also conducted. Exposure to sexual content across media, and perceived support from the media for teen sexual behavior, were the main media influence measures. RESULTS: Media explained 13% of the variance in intentions to initiate sexual intercourse in the near future, and 8-10% of the variance in light and heavy sexual behaviors, which was comparable to other contexts. Media influences also demonstrated significant associations with intentions and behaviors after all other factors were considered. All contextual factors, including media, explained 54% of the variance in sexual intentions and 21-33% of the variance in sexual behaviors. CONCLUSIONS: Adolescents who are exposed to more sexual content in the media, and who perceive greater support from the media for teen sexual behavior, report greater intentions to engage in sexual intercourse and more sexual activity. Mass media are an important context for adolescents' sexual socialization, and media influences should be considered in research and interventions with early adolescents to reduce sexual activity.

Adolescent↗
PubMed2000

Witchcraft or mycotoxin? The Salem witch trials.

BACKGROUND: The Salem witchcraft trials of 1692 have been studied by many historians looking for the complex social, political, and psychological determinants behind the community-wide hysteria that led to a travesty of justice and the deaths of 20 innocent Puritans. Recently, ergot poisoning has been put forth by some as a previously unsuspected cause of the bizarre behaviors of the young adolescent girls who accused the townsfolk of witchcraft. In this essay the circumstances behind the ergot poisoning theory for this historical event are described. When the evidence is weighed carefully both pro and con, it seems unlikely that ergotism explains much of what went on in colonial Salem.

Claviceps↗
PubMed2005

Reducing HIV infections at circuit parties: from description to explanation and principles of intervention design.

Circuit parties are weekend-long, erotically charged, drug-prevalent dance events attended by up to 25,000 self-identified gay and bisexual men who socialize and dance nonstop, sometimes for 24 hours or longer. Although these parties started originally as part of the gay community's response to raise HIV/AIDS awareness and to build community and cultural identity, they may have become a site for transmitting HIV across geographical regions and socioeconomic groups of gay and bisexual men. This article reviews the descriptive published studies on circuit parties. The authors use these studies and the literature on drug use and high-risk sexual behavior in gay and bisexual communities, along with sociological and social psychological research, to propose a causal model of why circuit parties may contribute to unsafe sexual practices that increase HIV infection risk. The authors abstract 5 prevention messages relevant to circuit parties and review intervention studies in nonparty settings for insight into how to reduce risky sexual behavior within circuit events. These intervention studies help to identify 5 context-specific groups that can effectively carry the prevention messages. The 5-by-5 matrix represents a first stage in developing a causal model for reducing HIV infections, along with evaluable principles of intervention, at circuit parties.

Bisexuality↗
PubMed2004

Experimental visualization of solute transport and mass transfer processes in two-dimensional conductivity fields with connected regions of high conductivity.

Solute transport displaying mass transfer behavior (i.e., tailing) occurs in many aquifers and soils. Spatial patterns of hydraulic conductivity may play a role because of both advection and diffusion through isolated low conductivity areas. We demonstrated such processes in laboratory experiments designed to visualize solute transport through a thin chamber (40 cm x 20 cm x 0.64 cm thick) packed with glass beads and containing circular emplacements of smaller glass beads with lower conductivity. The experiments used three different contrasts of conductivity between the large-bead matrix and the emplacements, targeting three different regimes of solute transport: low contrast, targeting macrodispersion; intermediate contrast, targeting advection-dominated mass transfer between the high-conductivity regions and the emplacements; and high contrast, targeting diffusion-dominated mass transfer. Use of a strong light source, a high-resolution CCD camera, and a colorimetric dye produced images with a spatial resolution of about 400 microm and a concentration range of approximately 2 orders of magnitude. These images confirm the existence of the three different regimes, and we observed tailing driven by both advection and diffusion. Outflow concentration measured by spectrophotometer achieved 3 orders of magnitude in concentration range and showed good agreement with known models in the case of dispersion and diffusive mass transfer, with estimated parameters close to a priori predictions. Existing models for diffusive mass transfer did notfitthe breakthrough curves from the intermediate-contrast chamber, but a model of slow advection through cylinders did. Thus, both breakthrough curves and chamber images confirm that different contrasts in small-scale K lead to different regimes of solute transport and thus require different models of upscaled solute transport.

Models, Theoretical↗
PubMed1986

Identification of new bile alcohols, 5 beta-cholestane-3 alpha,7 alpha,24,26-tetrol, 5 beta-cholestane-3 alpha,7 alpha,25,26-tetrol, and 5 beta-cholestane-3 alpha,7 alpha,26,27-tetrol in human gallbladder bile.

The nature of cholestanetetrols present as the glucurono-conjugates in human gallbladder bile was studied. Glucurono-conjugated bile alcohols were isolated by ion exchange chromatography and, after enzymatic hydrolysis, were fractionated by reversed phase partition chromatography to give a fraction containing tetrahydroxy bile alcohols which was analyzed by gas-liquid chromatography and mass spectrometry. Along with the three previously identified bile alcohols, 5 alpha- and 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha,24-tetrols, and 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha,26-tetrol, three new cholestanetetrols, possessing two hydroxyl groups in the ring system and two in the side chain, were detected in the tetrahydroxy bile alcohol fraction. These new bile alcohols were identified as 5 beta-cholestane-3 alpha, 7 alpha,24,26-tetrol, 5 beta-cholestane-3 alpha, 7 alpha,25,26-tetrol, and 5 beta-cholestane-3 alpha, 7 alpha,26,27-tetrol by direct comparison of their gas-liquid chromatographic behaviors and mass spectral data with those of authentic standards prepared from chenodeoxycholic acid by partial synthesis.

Bile↗
PubMedDate not supplied

Metabolism of methoxyphenamine in man and in monkey.

Metabolites of methoxyphenamine in the urine of human subjects and monkeys were separated by gas-liquid chromatography and identified by comparison of their chromatographic and mass spectrometric behavior with those of synthetic compounds. Aromatic O-demethylation, aromatic ring hydroxylation (both followed by glucuronide conjugation), and N-demethylation were shown to occur in man as well as in monkey. In man these were the principal metabolites, whereas in the monkey three additional unidentified major metabolites were formed.

Adult↗
PubMed2004

Emotional and behavioral consequences of bioterrorism: planning a public health response.

Millions of dollars have been spent improving the public health system's bioterrorism response capabilities. Yet relatively little attention has been paid to precisely how the public will respond to bioterrorism and how emotional and behavioral responses might complicate an otherwise successful response. This article synthesizes the available evidence about the likely emotional and behavioral consequences of bioterrorism to suggest what decision makers can do now to improve that response. It examines the emotional and behavioral impact of previous "bioterrorism-like" events and summarizes interviews with experts who have responded to such events or conducted research on the effects of community-wide disasters. The article concludes by reflecting on the evidence and experts' perspectives to suggest actions to be taken now and future policy and research priorities.

Bioterrorism↗
PubMed1995

Plasma fibrinogen levels and their correlates in 6457 coronary heart disease patients. The Bezafibrate Infarction Prevention (BIP) Study.

The association between fibrinogen measured in healthy individuals and subsequent development of ischemic heart disease is well established, but studies reporting fibrinogen levels in coronary heart disease patients are scarce. Plasma fibrinogen was determined for 5729 men and 728 women (aged 45 to 74) with established coronary heart disease, screened for participation in the Bezafibrate Infarction Prevention study, with the following lipid profile at the time of the first screening visit: total serum cholesterol < or = 270 mg/dl, high density lipoprotein cholesterol < or = 45 mg/dl and triglyceride < or = 300 mg/dl. Increased age was associated with augmented plasma fibrinogen values. Age-adjusted fibrinogen levels were higher in women than in men. A direct association was found between mean fibrinogen levels and low density lipoprotein cholesterol. On the other hand, the correlation with high density lipoprotein cholesterol was inverse. Fibrinogen was also associated with body mass index, behavioral variables and severity of coronary heart disease. In a multivariable linear regression analysis performed, risk factors considered explained merely 6 and 4% of fibrinogen variation for men and women, respectively. Therefore, most of the fibrinogen level variability in coronary heart disease patients is accounted for by factors that remain to be established by further research.

Age Factors↗
PubMed2001

Nonequilibrium mass transfer of multi-component NAPL in a soil column venting.

This study was conducted to investigate the mass transfer behavior for a multi-component system in the soil venting process. Soil venting experiments were conducted using gasoline-contaminated soil and models of local equilibrium assumption (LEA) and the first-order kinetic approach were used to descnbe the gasoline volatilization process. However, the focus was on the application of the kinetic model. In both models, thirteen major components of gasoline were selected for the model input and the rest of the gasoline was divided into 11 groups based on the retention times in the gas chromatography of gasoline. The LEA model had the tendency of underestimating the gas concentration at the initial phase and overestimating at the later phase due to the different volatilities of multi-components. n the kinetic model, the estimation of mass transfer coefficient values were carried out by adopting the relationship developed in the single-components system and choosing the appropriate modified Sherwood number. This method resulted in the good agreement with the simulation and the experimental results.

Carcinogens, Environmental↗
PubMed1992

Possible effects of the popular and medical recognition of bulimia nervosa.

Historical changes in psychological symptoms are analysed not only from a social causation approach but also from a labelling perspective. Modern eating disorders lend themselves to such an analysis because of their historical variability. Effects of the introduction and dispersion of the psychiatric concept of 'bulimia nervosa' at normal body weight and its propagation through the mass media are examined (relying on Devereux's model of 'ethnic disorders'). Data of an exploratory interview study with 39 bulimic patients evaluated along these lines (a) indicate that the recognition of bulimia has facilitated seeking of professional and non-professional help, (b) invite categorization of bulimic behaviour implying less self-blame, (c) render imitation of bulimia more probable, and (d) covary with less secretive illness behaviour indicating a broadening of underlying motivations.

Adolescent↗
PubMed1999

Identification of tyrosine sulfation in Conus pennaceus conotoxins alpha-PnIA and alpha-PnIB: further investigation of labile sulfo- and phosphopeptides by electrospray, matrix-assisted laser desorption/ionization (MALDI) and atmospheric pressure MALDI mass spectrometry.

Liquid chromatography/electrospray ionization mass spectrometry was used to investigate the peptide composition of the venom of Conus pennaceus, a molluscivorous cone shell from the Red Sea. Based on observed M(r)s, this venom contained all known conotoxins previously isolated and identified from this species. Interestingly, the doubly protonated species of only two of these conotoxins, alpha-PnIA and alpha-PnIB, showed additional related ions at +40 m/z (+80 Da), indicating the presence of either sulfation or phosphorylation in both components. High-performance liquid chromatographic (HPLC) fractions containing these two conotoxins were examined by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry in both positive and negative ion modes, as well as by MALDI high-energy collision-induced dissociation. These experiments established the presence of a single sulfated tyrosine residue within both alpha-PnIA and alpha-PnIB. Hence their post-translationally modified sequences are GCCSLPPCAANNPDY(S)C-NH2 (alpha-PnIA) and GCCSLPPCALSNPDY(S)C-NH2 (alpha-PnIB). This assignment was supported by comparison of their mass spectral behavior with that of known sulfated and phosphorylated peptides. This data clarified further the distinguishing features of the ionization and fragmentation of such modified peptides. Selective disulfide folding of synthetic alpha-PnIB demonstrated that both sulfated and non-sulfated toxins co-elute on reversed-phase HPLC and that alpha-PnIB possesses the same disulfide connectivity as other 'classical' alpha-conotoxins reported previously.

Amino Acid Sequence↗
PubMed2005

Identification of dehydro-ferulic acid-tyrosine in rye and wheat: evidence for a covalent cross-link between arabinoxylans and proteins.

To monitor chemical reactions between ferulate and proteins during breadmaking, 8-(14)C-(E)-ferulic acid-(d-galactopyranose-6'-yl)ester was synthesized as a radiotracer and added to wheat and rye flour prior to breadmaking. Breads were lyophilized, extracted by means of a modified Osborne fractionation, and the radioactivity of the fractions was determined by scintillation analysis. The major portion of the radioactivity remained in the water-soluble fraction. However, a significant enrichment of the tracer was also detected in the prolamin and glutelin fractions in comparison to the control experiment. Separation of the prolamin fraction by RP-HPLC and scintillation measurement of the fractions gave evidence for a chemical modification of the tracer. To determine the structure of the reaction product, the prolamin fractions were completely hydrolyzed to free amino acids by means of an enzyme cocktail, and the digests were studied by LC-MS. In one fraction, a newly formed compound was detected. Comparison of its chromatographic and mass spectrometric behavior with a synthetic reference compound gave evidence that the newly identified compound was a dehydroferulic acid-tyrosine cross-link. It is likely that this cross-link represented a covalent linkage between arabinoxylans and cereal proteins. The newly identified cross-link was also identified in wheat and rye flour doughs, which had been prepared without addition of the ferulate tracer. The relative concentration of the dehydroferulic acid-tyrosine cross-link increased during wheat dough preparation.

Bread↗