Rate constants for hydrogen atom transfer reactions from bis(cyclopentadienyl)titanium(III) chloride-complexed water and methanol to an alkyl radical.

Rate constants for hydrogen atom transfer reactions of the water, deuterium oxide, and methanol complexes of bis(cyclopentadienyl)titanium(III) chloride with the secondary alkyl radical 1-cyclobutyldodecyl (2) were determined using indirect kinetic methods. The rate constant for reaction of Cp2Ti(III)Cl-H2O in THF at ambient temperature was 1.0 x 10(5) M(-1) s(-1), and the kinetic isotope effect was kH/kD = 4.

Spectra and kinetic studies of the compound I derivative of cytochrome P450 119.

The Compound I derivative of cytochrome P450 119 (CYP119) was produced by laser flash photolysis of the corresponding Compound II derivative, which was first prepared by reaction of the resting enzyme with peroxynitrite. The UV-vis spectrum of the Compound I species contained an asymmetric Soret band that could be resolved into overlapping transitions centered at approximately 367 and approximately 416 nm and a Q band with lambda(max) approximately 650 nm. Reactions of the Compound I derivative with organic substrates gave epoxidized (alkene oxidation) and hydroxylated (C-H oxidation) products, as demonstrated by product studies and oxygen-18 labeling studies.

Correlates and predictors of HIV risk among inner-city African American female teenagers.

Objective Design: For human immunodeficiency virus (HIV)-related prevention initiatives to be most effective, they should be broad-based and incorporate multiple domains of influence. This study tested how several ecodevelopmental domains influenced HIV-risk related attitudes and behaviors in a community sample of African American female teens (N = 242).

Main Outcome Measures: Outcome measures were number of partners, frequency of intercourse, number of pregnancies, abstinence/condom use, HIV/AIDS-related attitudes and behaviors, and HIV testing.

Tunneling in C-H oxidation reactions by an oxoiron(IV) porphyrin radical cation: direct measurements of very large H/D kinetic isotope effects.

Rate constants for oxidations of benzyl alcohol-d0 and -d7 by oxoiron(IV) tetramesitylporphyrin radical cation perchlorate in acetonitrile were measured in single turnover kinetic studies. The kinetic isotope effect (kH/kD) increased from 28 at 23 degrees C to 360 at -30 degrees C due to extensive hydrogen atom tunneling that was analyzed in terms of a parabolic energy barrier to tunneling. Similarly, large KIE values were found for oxidations of ethylbenzene-d0 and -d10 at room temperature.

Rate constants and Arrhenius functions for ring opening of a cyclobutylcarbinyl radical clock and for hydrogen atom transfer from the Et(3)B-MeOH complex.

Kinetics of ring opening of the 1-cyclobutyldodecyl radical (1) were studied, and an Arrhenius function over the temperature range -20 to 47 degrees C was determined. The radical clock reaction has kinetics described by log k = 13.2 - 13.

Laser flash photolysis generation of high-valent transition metal-oxo species: insights from kinetic studies in real time.

High-valenttransition metal-oxo species are active oxidizing species in many metal-catalyzed oxidation reactions in both Nature and the laboratory. In homogeneous catalytic oxidations, a transition metal catalyst is oxidized to a metal-oxo species by a sacrificial oxidant, and the activated transition metal-oxo intermediate oxidizes substrates. Mechanistic studies of these oxidizing species can provide insights for understanding commercially important catalytic oxidations and the oxidants in cytochrome P450 enzymes.

Rate constants for 1,5- and 1,6-hydrogen atom transfer reactions of mono-, di-, and tri-aryl-substituted donors, models for hydrogen atom transfers in polyunsaturated fatty acid radicals.

Rate constants for 1,5- and 1,6-hydrogen atom transfer reactions in models of polyunsaturated fatty acid radicals were measured via laser flash photolysis methods. Photolyses of PTOC (pyridine-2-thioneoxycarbonyl) ester derivatives of carboxylic acids gave primary alkyl radicals that reacted by 1,5-hydrogen transfer from mono-, di-, and tri-aryl-substituted positions or 1,6-hydrogen transfer from di- and tri-aryl-substituted positions to give UV-detectable products. Rate constants for reactions in acetonitrile at room temperature ranged from 1 x 10(4) to 4 x 10(6) s(-1).

X-ray absorption spectroscopic characterization of a cytochrome P450 compound II derivative.

The cytochrome P450 enzyme CYP119, its compound II derivative, and its nitrosyl complex were studied by iron K-edge x-ray absorption spectroscopy. The compound II derivative was prepared by reaction of the resting enzyme with peroxynitrite and had a lifetime of approximately 10 s at 23 degrees C. The CYP119 nitrosyl complex was prepared by reaction of the enzyme with nitrogen monoxide gas or with a nitrosyl donor and was stable at 23 degrees C for hours.

Protective and risk influences of drug use among a multiethnic sample of adolescent boys.

A measurement model was analyzed to demonstrate a differential distribution and cumulative exposure to psychosocial risk and protective influences of adolescent drug use among ethnically-diverse adolescent samples. The sample included U.S.

Kinetics and mechanism of oxidation reactions of porphyrin-iron(IV)-oxo intermediates.

The kinetics of the reactions of three porphyrin-iron(IV)-oxo derivatives with alkenes and benzylic alcohols were measured. The iron-oxo systems studied were 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin-iron(IV)-oxo (2a), 5,10,15,20-tetrakis(2,6-difluorophenyl)porphyrin-iron(IV)-oxo (2b), and 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin-iron(IV)-oxo (2c). Species 2 were stable for hours at room temperature as dilute solutions in acetonitrile and reacted hundreds to thousands of times faster in the presence of high concentrations of substrates.

Parenting as a moderator of minority, adolescent victimization and violent behavior in high-risk neighborhoods.

Adolescent male youth in high-crime neighborhoods are at the greatest risk for personal victimization and violent behavior. The temporal relationship between victimization and violent behavior for minority youth in high-crime neighborhoods was examined to determine whether victimization is a risk factor for or by-product of violent behavior. Whether parenting and other control factors moderated the relationship between victimization and violent behavior was also examined.

Rate constants for reactions of alkyl radicals with water and methanol complexes of triethylborane.

Reactions of secondary alkyl radicals with triethylborane and several of its complexes were studied. The H-atom transfer reactions from Et3B-OH2 and Et3B-OD2 were suppressed by addition of pyridine to the reaction mixture. Rate constants for reactions of secondary alkyl radicals with triethylborane and its complexes with water, deuterium oxide, methanol, and THF at ambient temperature were determined by radical clock methods.

Developing a healthy OR workplace.

Innovation is required to develop a positive work environment in the OR. Components of a healthy or workplace identified by staff members of three surgical departments are quality practice standards, excellence in patient care systems, a functional physical environment, effective staff systems, meaningful role definition and clarity, and identified guidelines for teamwork. In one or, staff members working on a communication team developed and implemented an action plan to enhance respect in the OR setting.

Expansion of adult hepatitis A and B vaccination in STD clinics and other settings in New York State.

Since 1995, the New York State (NYS) Adult Hepatitis Vaccination Program has promoted adult hepatitis B vaccination for those receiving sexually transmitted disease (STD) clinic services. An average of 6,333 doses was administered annually from 1995 to 1999. By 2000, only 15 of 57 county STD programs in NYS outside of New York City participated.

Compatible injection and detection systems for studying the kinetics of excess electron transfer.

[reaction: see text] A design for fast kinetic studies of electron transfer in radical anions is reported. alpha-Hydroxy radicals formed by 355 nm laser flash photolysis of alpha-phenacyl alcohols are deprotonated under basic conditions to give ketyl radical anions that serve as electron injectors in inter- and intramolecular electron-transfer reactions. The 2,2-diphenylcyclopropyl group serves as a reporter.

Induction of the celC operon of Clostridium thermocellum by laminaribiose.

Clostridium thermocellum is an anaerobic, thermophilic, cellulolytic, and ethanogenic bacterium. It produces an extracellular multiprotein complex termed the cellulosome, which consists of >70 subunits, most of them glycosyl hydrolases. It also produces many free glycosyl hydrolases.

Products from enzyme-catalyzed oxidations of norcarenes.

Recent studies revealed that norcarane (bicyclo[4.1.0]heptane) is oxidized to 2-norcarene (bicyclo[4.

Desaturase reactions complicate the use of norcarane as a mechanistic probe. Unraveling the mixture of twenty-plus products formed in enzyme-catalyzed oxidations of norcarane.

Norcarane, bicyclo[4.1.0]heptane, has been widely used as a mechanistic probe in studies of oxidations catalyzed by several iron-containing enzymes.

Photochemical production of a highly reactive porphyrin-iron-oxo species.

Oxidation of 5,10,15,20-tetramesitylporphyrinatoiron(III) perchlorate, (TMP)FeIII(ClO4), with ferric perchlorate in acetonitrile gave a metastable species identified as (TMP)FeIV(ClO4)2 that decayed within seconds to the known isomeric species (TMP*+)FeIII(ClO4)2. Irradiation of the metastable species with 355 nm laser light gave a highly reactive transient that reacts with simple organic reductants (alkenes and arylalkanes) 5 orders of magnitude faster than known Compound I analogues, (TMP*+)FeIV(O)(X-).

Kinetic studies of a fast, reversible alkene radical cation cyclization reaction.

The radical cation formed by mesylate heterolysis from the 1,1-dimethyl-7,7-diphenyl-2-mesyloxy-6-heptenyl radical was studied in several solvents. Computational results suggest that the initially formed acyclic radical cation is a resonance hybrid with partial positive charge in both double bonds of 1,1-diphenyl-7-methyl-1,6-octadiene (10). Thiophenol trapping was used as the competing reaction for kinetic determinations.

Radical heterolysis reactions. Dynamics of formation, collapse, and solvation of ion pairs determined by a competition kinetic method.

The kinetics of radical heterolysis reactions, including rate constants for radical cation-anion contact ion pair formation, collapse of the contact pair back to the parent radical, and separation of the contact pair to a solvent-separated ion pair or free ions were obtained in several solvents for a beta-mesyloxy radical. Rate constants were determined from indirect kinetic studies using thiophenol as both a radical trapping agent via H-atom transfer and an alkene radical cation trapping agent via electron transfer. [reaction: see text].

Corneal avascularity is due to soluble VEGF receptor-1.

Corneal avascularity-the absence of blood vessels in the cornea-is required for optical clarity and optimal vision, and has led to the cornea being widely used for validating pro- and anti-angiogenic therapeutic strategies for many disorders. But the molecular underpinnings of the avascular phenotype have until now remained obscure and are all the more remarkable given the presence in the cornea of vascular endothelial growth factor (VEGF)-A, a potent stimulator of angiogenesis, and the proximity of the cornea to vascularized tissues. Here we show that the cornea expresses soluble VEGF receptor-1 (sVEGFR-1; also known as sflt-1) and that suppression of this endogenous VEGF-A trap by neutralizing antibodies, RNA interference or Cre-lox-mediated gene disruption abolishes corneal avascularity in mice.

Childhood adversity, poly-substance use, and disordered eating in adolescent Latinas: mediated and indirect paths in a community sample.

Objective: Although many studies have identified associations between childhood maltreatment and later substance use and disordered eating, few have examined causal or explanatory pathways, and whether victim characteristics predict the development of one versus the other of these outcomes remains uninvestigated. Furthermore, relatively little childhood maltreatment research has examined Latino samples. To address these gaps, this study examined among Latina adolescents the effects of sexual abuse, physical/emotional abuse, neglect, disconnection from family, and parental alcohol problems on poly-substance use and disordered eating, and whether five individual characteristics explain or differentiate these outcomes.

Kinetics of two-electron oxidations by the compound I derivative of chloroperoxidase, a model for cytochrome P450 oxidants.

[structure: see text] Rate constants for two-electron oxidation reactions of Compound I from chloroperoxidase (CPO) with a variety of substrates were measured by stopped-flow kinetic techniques. The thiolate ligand of CPO Compound I activates the iron-oxo species with the result that oxidation reactions are 2 to 3 orders of magnitude faster than oxidations by model iron(IV)-oxo porphyrin radical cations containing weaker binding counterions.