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1.
J Midwifery Womens Health ; 69(1): 9-16, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-37641584

RESUMO

INTRODUCTION: Prior to the coronavirus disease 2019 (COVID-19) pandemic, studies of innovative telehealth perinatal care models showed similar clinical outcomes and perceived quality of care between groups receiving a combination of virtual video and in-person visits. However, these studies included primarily White, English-speaking participants, excluding those who were economically disenfranchised or did not speak English. The purpose of this qualitative study was to describe perinatal patients' and providers' experiences with telehealth during and after the acute phase of the COVID-19 pandemic to inform future utilization of telehealth to drive the delivery of high-quality, accessible, and equitable perinatal care to diverse communities. METHODS: This descriptive qualitative study included a purposive sample of 14 patients and 17 providers who received or provided perinatal care via telehealth in either a certified nurse-midwifery practice or the nurse-family partnership care model between March 2020 and April 2022. Maximum variation sampling offered a diverse population based on race, ethnicity, and rurality. Researchers conducted 2 rounds of semistructured interviews with a focus on understanding social and geographic context. RESULTS: Six themes were identified through inductive analysis: (1) unexpected advantages of telehealth, (2) patient empowerment, (3) providers' fear of adverse outcomes, (4) concern for equitable care, (5) strategies to enhance the telehealth experience, and (6) strategies to address access to perinatal telehealth. Patients appreciated the increased ease and reduced cost of accessing visits, which led to fewer missed appointments. Health care providers saw great opportunity in telehealth but expressed concerns about accessibility for patients with language barriers or limited resources. DISCUSSION: This study provides insight into priorities for continued telehealth utilization focused on providing equitable access to perinatal care. Rather than returning to practices from before the COVID-19 pandemic formed from longstanding routines and perceived limitations, providers are encouraged to capitalize on the rapid innovations in telehealth to build a more effective, equitable, and patient-centered approach to perinatal care.


Assuntos
COVID-19 , Tocologia , Telemedicina , Feminino , Gravidez , Humanos , Pandemias , COVID-19/epidemiologia , Certificação
2.
Breastfeed Med ; 18(9): 701-711, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37729034

RESUMO

Background and Objectives: Evidence is lacking on the safety of marijuana (MJ) exposure on the fetus and neonate, and current guidelines vary across professional organizations. We examined variation in hospital practices regarding use of mother's own milk (MOM) in the setting of perinatal MJ exposure based on hospital location and state MJ legal designation. Methods: We conducted a cross-sectional electronic survey of U.S. perinatal health care workers on hospital policies and clinical practice regarding maternal MJ use from November 2021 to April 2022. We analyzed responses from those working in states with legal recreational MJ (REC), MJ legal for medical use only (MED), and illegal MJ (NON), based on legalization status as of 2021. Results: Two thousand six hundred eighty-three surveys were analyzed from 50 states and the District of Columbia, with 1,392 respondents from REC states, 524 from NON states, and 668 from MED states. Hospital policies and practices showed significant differences between facilities from REC and NON states. REC states were more likely to have policies allowing use of MOM from mothers using MJ after delivery and less likely to routinely include cannabinoids in toxicology testing. Hospital policies also varied within individual hospitals between well baby nurseries and neonatal intensive care units. Conclusions: Hospital practices vary widely surrounding provision of MOM in the presence of maternal MJ use, based on state legalization status and hospital unit of care. Clear guidelines across professional organizations regarding perinatal MJ exposure, regardless of legality, are warranted to improve consistency of care and patient education.


Assuntos
Cannabis , Uso da Maconha , Transtornos Relacionados ao Uso de Substâncias , Lactente , Feminino , Recém-Nascido , Gravidez , Humanos , Aleitamento Materno , Estudos Transversais , Lactação , Hospitais , Mães
3.
Policy Polit Nurs Pract ; 24(2): 102-109, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36628422

RESUMO

Lack of access to birth facilities and maternity care providers has contributed to rising US maternal mortality and morbidity rates, especially among women in rural areas. Evidence supports the increased use of midwives as a potential solution for access-to-care issues. This observational survey was conducted to identify the practice environment for Certified Nurse-Midwives® in Colorado for the purpose of informing future workforce expansion. Study results indicate that midwives provide services aligned with the midwifery model of care and have mostly autonomous practice in hospitals where midwifery practices are already established. However, there is limited use of midwives, as fewer than half of Colorado's 69 birthing hospitals have midwifery practices, and financial constraint created by low Medicaid reimbursement could be a limiting factor in establishing new midwifery practices. Policy recommendations based on survey results include (a) support for midwifery education and workforce development, (b) removal of hospital-level restrictions for privileges of midwives, and (c) consideration for public payment models that promote expansion of midwifery practices.


Assuntos
Serviços de Saúde Materna , Tocologia , Enfermeiros Obstétricos , Feminino , Humanos , Gravidez , Colorado , Hospitais
4.
Behav Brain Res ; 419: 113687, 2022 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-34838930

RESUMO

Adolescence is a critical period of development, during which the brain undergoes rapid maturation. Problematically, adolescents are the top consumers of high fructose corn syrup (HFCS) sweetened beverages and snacks, which may have neurodevelopmental consequences. While HFCS consumption has been linked to an increased likelihood of obesity and other physical health impairments, the link between HFCS and persistent behavioral changes is not yet fully established. The present study aimed to assess whether adolescent HFCS consumption could lead to alterations in adult behaviors and protein expression, following cessation. Adolescent HFCS-exposure contributed to deficits in learning and motivation on an effort-related T-Maze procedure, as well as increased immobility time in the forced swim paradigm during adulthood. Molecularly, protracted decreases in accumbal dopamine D1 and D2 receptors and protein kinase G (PKG), as well as increases in tyrosine hydroxylase and GluA2 receptor subunits, were observed following HFCS-exposure. Taken together, these data suggest that adolescent HFCS-consumption leads to protracted dysfunction in affective behaviors and alterations in accumbal proteins which persist following cessation of HFCS-consumption.


Assuntos
Comportamento Animal , Disfunção Cognitiva , Proteínas Quinases Dependentes de GMP Cíclico , Dieta da Carga de Carboidratos/efeitos adversos , Xarope de Milho Rico em Frutose/efeitos adversos , Motivação , Núcleo Accumbens , Receptores Dopaminérgicos , Fatores Etários , Animais , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Disfunção Cognitiva/induzido quimicamente , Disfunção Cognitiva/metabolismo , Disfunção Cognitiva/fisiopatologia , Proteínas Quinases Dependentes de GMP Cíclico/efeitos dos fármacos , Proteínas Quinases Dependentes de GMP Cíclico/metabolismo , Depressão/induzido quimicamente , Depressão/metabolismo , Depressão/fisiopatologia , Modelos Animais de Doenças , Masculino , Motivação/fisiologia , Núcleo Accumbens/efeitos dos fármacos , Núcleo Accumbens/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores Dopaminérgicos/efeitos dos fármacos , Receptores Dopaminérgicos/metabolismo
5.
J Perinat Neonatal Nurs ; 35(2): 150-159, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33900245

RESUMO

The complexities of providing quality perinatal care within rural communities provide significant challenges to providers and policy makers. Provision of healthcare in rural communities is challenging on individual as well as community-based levels. A quality improvement lens is applied to consider key challenges that pertain to patients, providers, place, and policy. Potential solutions from a provider perspective include nurse-midwifery care and inclusion of advanced practice providers in a variety of specialties in addition to creating care models for registered nurses to practice at the top of their scope. To enhance access in the rural place, telehealth and coordination activities are recommended. Finally, policy approaches such as Perinatal Care Collaboratives, Area Health Education Centers, and enhanced financial resources to eliminate socioeconomic disparities will enhance perinatal care in rural communities.


Assuntos
Tocologia , Telemedicina , Criança , Feminino , Humanos , Recém-Nascido , Assistência Perinatal , Gravidez , Qualidade da Assistência à Saúde , População Rural
6.
Animals (Basel) ; 11(2)2021 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-33562360

RESUMO

There is a strong industry demand for technically simple and highly efficacious alternatives to heat cautery disbudding in goat kids that can be performed as a stand-alone procedure without adjunct anesthesia, and that result in improved overall welfare through reduced acute pain, reduced tissues healing interval, and a consistent safety record. The objective of this study was to consider the net effect of disbudding techniques on goat welfare by examining vocalization frequency, long-term efficacy and animal safety associated with four alternative caprine disbudding methods against sham-disbudded and heat-cautery controls. Sixty-five commercial male dairy kids were disbudded at 3-10 days of age with one of six disbudding treatments (clove oil injection, caustic paste, two cryosurgical methods, heat-cautery, and sham procedure). Heat cautery was 91% effective, caustic paste was 55% effective, and the other treatments were ineffective. Heat cautery and sham procedures resulted in similar vocalization efforts; freezing with a liquid-nitrogen cooled iron resulted in significantly greater vocalization numbers. No unintended paste transfer injuries were observed with short-term application of the caustic paste. Heat cautery resulted in numerous superficial infections but no permanent injury. Clove oil injection was associated with several unexpected and severe complications including unintended tissue necrosis, temporary paresis, skull defects, meningitis, and death. Collectively, we did not find that any of the alternative methods of disbudding provided a feasible option over heat cautery to improve welfare.

7.
J Midwifery Womens Health ; 65(3): 335-341, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32452155

RESUMO

INTRODUCTION: Women desire safe and effective choices for pain management during labor. Currently, neuraxial and opioid analgesia are the most common methods used in the United States. The purpose of this study was to investigate demographic characteristics, safety, and satisfaction in a cohort of parturients who used inhaled nitrous oxide (N2 O) analgesia and to determine predictors of conversion from N2 O to neuraxial analgesia. METHODS: This was a prospective chart review study. Individuals aged at least 18 years who used inhaled N2 O during the first or second stage of labor between March 1, 2016, and July 23, 2017, on the labor and delivery unit of one academic medical center (N = 463) and their neonates were included. Data describing maternal and neonatal factors are reported. Logistic regression and chi-square tests were used to model the effects of oxytocin augmentation, labor induction, parity, prior cesarean birth, pre-N2 O cervical dilatation, and post-N2 O cervical dilatation on the odds of conversion from N2 O to neuraxial analgesia. RESULTS: In this cohort, 31% who chose N2 O for analgesia did not convert to any other analgesic method. Significant positive predictors for conversion from N2 O to neuraxial analgesia included labor induction (odds ratio [OR], 2.9; 95% CI, 1.7-5.0), oxytocin augmentation (OR, 3.1; 95% CI, 1.6-6.0), and labor after cesarean (OR, 6.4; 95% CI, 2.5-16.5). Multiparity (OR, 0.4; 95% CI, 0.2-0.6) and post-N2 O cervical dilatation (OR, 0.8; 95% CI, 0.7-0.9) were negative predictors. Adverse effects related to N2 O use during labor were rare (8%) and were not a significant reason for conversion to neuraxial analgesia. Parturients had moderately high satisfaction with N2 O for pain management (11-point scale, mean [SD], 7.4 [2.9]). Five-minute Apgar scores were 7 or greater in 97.8% of the newborns. DISCUSSION: Understanding predictors of conversion from inhaled N2 O to neuraxial analgesia may assist perinatal care providers in their discussions with women about analgesia options during labor. N2 O is a useful, safe option for labor analgesia in the United States.


Assuntos
Analgesia Epidural/estatística & dados numéricos , Analgesia Obstétrica/estatística & dados numéricos , Analgésicos não Narcóticos/uso terapêutico , Anestésicos Inalatórios/efeitos adversos , Dor do Parto/tratamento farmacológico , Óxido Nitroso/efeitos adversos , Adulto , Cesárea , Estudos de Coortes , Feminino , Humanos , Recém-Nascido , Trabalho de Parto , Manejo da Dor/métodos , Paridade , Satisfação do Paciente , Gravidez , Estudos Prospectivos , Estados Unidos
8.
Neuropharmacology ; 150: 153-163, 2019 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-30926450

RESUMO

Accumulating evidence indicates that exposure to general anesthetics during infancy and childhood can cause persistent cognitive impairment, alterations in synaptic plasticity, and, to a lesser extent, increased incidence of behavioral disorders. Unfortunately, the developmental parameters of susceptibility to general anesthetics are not well understood. Adolescence is a critical developmental period wherein multiple late developing brain regions may also be vulnerable to enduring general anesthetic effects. Given the breadth of the adolescent age span, this group potentially represents millions more individuals than those exposed during early childhood. In this study, isoflurane exposure within a well-characterized adolescent period in Sprague-Dawley rats elicited immediate and persistent anxiety- and impulsive-like responding, as well as delayed cognitive impairment into adulthood. These behavioral abnormalities were paralleled by atypical dendritic spine morphology in the prefrontal cortex (PFC) and hippocampus (HPC), suggesting delayed anatomical maturation, and shifts in inhibitory function that suggest hypermaturation of extrasynaptic GABAA receptor inhibition. Preventing this hypermaturation of extrasynaptic GABAA receptor-mediated function in the PFC selectively reversed enhanced impulsivity resulting from adolescent isoflurane exposure. Taken together, these data demonstrate that the developmental window for susceptibility to enduring untoward effects of general anesthetics may be much longer than previously appreciated, and those effects may include affective behaviors in addition to cognition.


Assuntos
Afeto/efeitos dos fármacos , Anestésicos Gerais/farmacologia , Comportamento Animal/efeitos dos fármacos , Cognição/efeitos dos fármacos , Isoflurano/farmacologia , Plasticidade Neuronal/efeitos dos fármacos , Animais , Espinhas Dendríticas/efeitos dos fármacos , Comportamento Exploratório/efeitos dos fármacos , Comportamento Impulsivo/efeitos dos fármacos , Masculino , Córtex Pré-Frontal/efeitos dos fármacos , Células Piramidais/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley
9.
Curr Chem Genomics ; 2: 16-28, 2008 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-20161840

RESUMO

Proteases play important roles in a variety of disease processes. Understanding their biological functions underpins the efforts of drug discovery. We have developed a bioluminescent protease assay using a circularly permuted form of firefly luciferase, wherein the native enzyme termini were joined by a peptide containing a protease site of interest. Protease cleavage of these mutant luciferases greatly activates the enzyme, typically over 100 fold. The mutant luciferase substrates are easily generated by molecular cloning and cell-free translation reactions and thus the protease substrates do not need to be chemically synthesized or purchased. The assay has broad applicability using a variety of proteases and their cognate sites and can sensitively detect protease activity. In this report we further demonstrate its utility for the evaluation of protease recognition sequence specificity and subsequent establishment of an optimized assay for the identification and characterization of protease inhibitors using high throughput screening.

10.
Acc Chem Res ; 40(11): 1208-16, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17970599

RESUMO

The solubilities of gases in ionic liquids are important in evaluating ionic liquids as solvents for reactions involving permanent gases, as gas storage media, and as solvents for gas separations. Gas solubilities are also important in developing methods to separate solutes from ionic liquid solutions. Here we describe our measurements of the solubilities of CO2, CH4, C2H 6, C2H 4, O2, and N2 in 1-hexyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide and compare these results to our previous investigations. In addition, focus is placed on efforts to tailor ionic liquids to enhance the solubilities of some gases, with particular emphasis on carbon dioxide.


Assuntos
Dióxido de Carbono/química , Etano/química , Imidas/química , Líquidos Iônicos/química , Metano/química , Nitrogênio/química , Oxigênio/química , Compostos de Piridínio/química , Simulação por Computador , Modelos Químicos , Solubilidade , Propriedades de Superfície
11.
J Phys Chem B ; 111(30): 9001-9, 2007 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-17608519

RESUMO

Previously we showed that CO2 could be used to extract organic molecules from ionic liquids without contamination of the ionic liquid. Consequently a number of other groups demonstrated that ionic liquid/CO2 biphasic systems could be used for homogeneously catalyzed reactions. Large differences in the solubility of various gases in ionic liquids present the possibility of using them for gas separations. More recently we and others have shown that the presence of CO2 increases the solubility of other gases that are poorly soluble in the ionic liquid phase. Therefore, a knowledge and understanding of the phase behavior of these ionic liquid/CO2 systems is important. With the aim of finding ionic liquids that improve CO2 solubility and gaining more information to help us understand how to design CO2-philic ionic liquids, we present the low- and high-pressure measurements of CO2 solubility in a range of ionic liquids possessing structures likely to increase the solubility of CO2. We examined the CO2 solubility in a number of ionic liquids with systematic increases in fluorination. We also studied nonfluorinated ionic liquids that have structural features known to improve CO2 solubility in other compounds such as polymers, for example, carbonyl groups and long alkyl chains with branching or ether linkages. Results show that ionic liquids containing increased fluoroalkyl chains on either the cation or anion do improve CO2 solubility when compared to less fluorinated ionic liquids previously studied. It was also found that it was possible to obtain similar, high levels of CO2 solubility in nonfluorous ionic liquids. In agreement with our previous results, we found that the anion frequently plays a key role in determining CO2 solubility in ionic liquids.

12.
J Phys Chem B ; 110(31): 15059-62, 2006 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-16884216

RESUMO

Measurements of the solubility of sulfur dioxide (SO(2)) in the ionic liquids 1-n-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf(2)N]) and 1-n-hexyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide ([hmpy][Tf(2)N]) at temperatures from 25 to 60 degrees C and pressures up to 4 bar indicate that large amounts (up to 85 mol %) of SO(2) dissolve in ionic liquids by simple physical absorption.


Assuntos
Imidazóis/química , Imidas/química , Compostos de Piridínio/química , Dióxido de Enxofre/química , Líquidos Iônicos/química , Pressão , Solubilidade , Temperatura
13.
Enzymes ; 24: 245-72, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-26718043

RESUMO

Proteins that terminate in a C-terminal CaaX motif undergo three sequential posttranslational modifications: isoprenylation of the cysteine residue, endoproteolysis of the -aaX residues, and methylation of the isoprenylated cysteine by an isoprenylcysteine carboxylmethyltransferase (Icmt). Among the proteins that contain this CaaX sequence are the Ras superfamily of G-proteins and other signal transduction proteins, the nuclear lamins, and the yeasta-factor mating pheromone. Icmt is a mechanistically intriguing enzyme that is unique among S-adenosyl-l-methionine (SAM)-dependent methyltransferases in that it is an integral membrane enzyme localized to the endoplasmic reticulum. It must also accommodate chemically diverse cofactor and substrate molecules; namely, the hydrophilic methyl-donating cofactor SAM and a lipophilic isoprenylated protein substrate, respectively. A complete picture of the cellular consequences of carboxylmethylation of isoprenylated proteins is still emerging. It is known, however, that methylation is critical for the proper localization of the CaaX protein Ras and may be essential for oncogenic transformation. Thus,Icmt may prove to be an excellent chemotherapeutic target. In this review, the structure and function of the family of Icmt enzymes are discussed, as well as recent advances in the development of small-molecule inhibitors of this key enzyme in the CaaX posttranslational processing pathway.

14.
Bioorg Med Chem Lett ; 15(22): 5080-3, 2005 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-16183278

RESUMO

N-Acetyl-S-farnesyl cysteine (AFC) is the minimal synthetic substrate for the enzyme Icmt, which methylates prenylated proteins. The desthio-AFC isostere 2 has been synthesized in racemic form. This analog was not an Icmt substrate, but instead a weak inhibitor with an IC50 of approximately 325 microM.


Assuntos
Cisteína/análogos & derivados , Cisteína/síntese química , Sulfetos/síntese química , Concentração Inibidora 50 , Metiltransferases/antagonistas & inibidores , Metiltransferases/metabolismo , Estrutura Molecular , Sulfetos/química , Terpenos/química , Terpenos/metabolismo
15.
J Biol Chem ; 280(33): 29454-61, 2005 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-15946942

RESUMO

Isoprenylcysteine carboxylmethyltransferase (Icmt) is an integral membrane protein localized to the endoplasmic reticulum of eukaryotic cells that catalyzes the post-translational alpha-carboxylmethylesterification of CAAX motif proteins, including the oncoprotein Ras. Prior to methylation, these protein substrates all contain an isoprenylcysteine residue at the C terminus. In this study, we developed a variety of substrates and inhibitors of Icmt that vary in the isoprene moiety in order to gain information about the nature of the lipophilic substrate binding site. These isoprenoid-modified analogs of the minimal Icmt substrate N-acetyl-S-farnesyl-L-cysteine (AFC) were synthesized from newly and previously prepared farnesol analogs. Using both yeast and human Icmt enzymes, these compounds were found to vary widely in their ability to act as substrates, supporting the isoprenoid moiety as a key substrate recognition element for Icmt. Compound 3 is a competitive inhibitor of overexpressed yeast Icmt (K(I) = 17.1 +/- 1.7 microm). Compound 4 shows a mix of competitive and uncompetitive inhibition for both the yeast and the human Icmt proteins (yeast K(IC) = 35.4 +/- 3.4 microm, K(IU) = 614.4 +/- 148 microm; human K(IC) = 119.3 +/- 18.1 microm, K(IU) = 377.2 +/- 42.5 microm). These data further suggest that differences in substrate specificity exist between the human and yeast enzymes. Biological studies suggest that inhibition of Icmt results in Ras mislocalization and loss of cellular transformation ability, making Icmt an attractive and novel anticancer target. Further elaboration of the lead compounds synthesized and assayed here may lead to clinically useful higher potency inhibitors.


Assuntos
Inibidores Enzimáticos/farmacologia , Proteínas Metiltransferases/antagonistas & inibidores , Proteínas Metiltransferases/metabolismo , Terpenos/metabolismo , Sítios de Ligação , Humanos , Saccharomyces cerevisiae/enzimologia , Relação Estrutura-Atividade , Especificidade por Substrato
16.
Bioconjug Chem ; 16(3): 490-3, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15898712

RESUMO

We have designed, synthesized, and characterized a metal chelating compound that is based on the structure of cholesterol and contains the high affinity metal chelating group, lysine nitrilotriacetic acid (Lys-NTA). Using the enzyme isoprenylcysteine carboxylmethyltransferase (Icmt) from yeast as a model integral membrane metalloenzyme, we find that this agent potently inhibits Icmt activity with an IC(50) value between 35 and 75 microM, which is at least 40 times more potent than the best known Icmt metal chelating inhibitor, Zincon. We propose that the rigid hydrophobic cholesterol moiety promotes partitioning into the membrane, enabling the metal-binding NTA group(s) to inactivate the enzyme by metal chelation. Because this compound is based on a naturally occurring membrane lipid and appears to chelate metals buried deeply within water insoluble environments, this agent may also be useful as a general tool for identifying previously unappreciated metal dependencies of other classes of membrane proteins.


Assuntos
Membrana Celular/enzimologia , Quelantes/química , Quelantes/farmacologia , Colesterol/química , Metais/química , Proteínas Metiltransferases/antagonistas & inibidores , Proteínas Metiltransferases/metabolismo , Membrana Celular/efeitos dos fármacos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Estrutura Molecular , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/enzimologia , Proteínas de Saccharomyces cerevisiae
17.
Chem Commun (Camb) ; (20): 2603-5, 2005 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-15900341

RESUMO

The presence of CO(2) increases the solubility of O(2) and CH(4) in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide at 25 degrees C and pressures to 13 bar.


Assuntos
Dióxido de Carbono/química , Imidazóis/química , Imidas/química , Metano/química , Oxigênio/química , Solubilidade , Solventes/química
18.
J Phys Chem B ; 109(13): 6366-74, 2005 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-16851709

RESUMO

This work presents the results of solubility measurements for a series of gases in 1-n-butyl-3-methyl imidazolium tetrafluoroborate and 1-n-butyl-3-methyl imidazolium bis(trifluoromethylsulfonyl) imide. The gases considered include benzene, carbon dioxide, nitrous oxide, ethylene, ethane, oxygen, and carbon monoxide. Carbon dioxide and oxygen solubilities are also reported in methyl-tributylammonium bis(trifluoromethylsulfonyl) imide, butyl-methyl pyrrolidinium bis(trifluoromethylsulfonyl) imide, and tri-isobutyl-methyl phosphonium p-toluenesulfonate. We report the associated Henry's constants and enthalpies and entropies of absorption. In general, benzene, followed by carbon dioxide and nitrous oxide, have the highest solubilities and strongest interactions with the ionic liquids, followed by ethylene and ethane. Oxygen had very low solubilities and weak interactions. Carbon monoxide had a solubility below the detection limit of our apparatus. Ionic liquids with the bis(trifluoromethylsulfonyl) imide anion had the largest affinity for CO(2), regardless of whether the cation was imidazolium, pyrrolidinium, or tetraalkylammonium. These results suggest that the nature of the anion has the most significant influence on the gas solubilities.

19.
J Biol Chem ; 280(8): 7336-45, 2005 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-15611058

RESUMO

Numerous proteins, including Ras, contain a C-terminal CAAX motif that directs a series of three sequential post-translational modifications: isoprenylation of the cysteine residue, endoproteolysis of the three terminal amino acids and alpha-carboxyl methylesterification of the isoprenylated cysteine. This study focuses on the isoprenylcysteine carboxylmethyltransferase (Icmt) enzyme from Saccharomyces cerevisiae, Ste14p, the founding member of a homologous family of endoplasmic reticulum membrane proteins present in all eukaryotes. Ste14p, like all Icmts, has multiple membrane spanning domains, presenting a significant challenge to its purification in an active form. Here, we have detergent-solubilized, purified, and reconstituted enzymatically active His-tagged Ste14p from S. cerevisiae, thus providing conclusive proof that Ste14p is the sole component necessary for the carboxylmethylation of isoprenylated substrates. Among the extensive panel of detergents that was screened, optimal solubilization and retention of Ste14p activity occurred with n-dodecyl-beta-d-maltoside. The activity of Ste14p could be further optimized upon reconstitution into liposomes. Our expression and purification schemes generate milligram quantities of pure and active Ste14p, which is highly stable under many conditions. Using pure reconstituted Ste14p, we demonstrate quantitatively that Ste14p does not have a preference for the farnesyl or geranylgeranyl moieties in the model substrates N-acetyl-S-farnesyl-l-cysteine (AFC) and N-acetyl-S-geranylgeranyl-l-cysteine (AGGC) in vitro. In addition to catalyzing methylation of AFC, we also show that purified Ste14p methylates a known in vivo substrate, Ras2p. Evidence that metals ions are required for activity of Ste14p is also presented. These results pave the way for further characterization of pure Ste14p, as well as determination of its three-dimensional structure.


Assuntos
Acetilcisteína/análogos & derivados , Proteínas Metiltransferases/química , Proteínas de Saccharomyces cerevisiae/química , Acetilcisteína/metabolismo , Lipossomos , Metais , Metilação , Proteínas Metiltransferases/isolamento & purificação , Proteínas de Saccharomyces cerevisiae/isolamento & purificação , Proteínas de Saccharomyces cerevisiae/metabolismo , Especificidade por Substrato , Proteínas ras/metabolismo
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