Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 51
Filtrar
1.
Clin Infect Dis ; 76(7): 1209-1217, 2023 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-36401872

RESUMO

BACKGROUND: Streptococcus pneumoniae interacts with numerous viral respiratory pathogens in the upper airway. It is unclear whether similar interactions occur with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: We collected saliva specimens from working-age adults undergoing SARS-CoV-2 molecular testing at outpatient clinics and via mobile community-outreach testing between July and November 2020 in Monterey County, California. After bacterial culture enrichment, we tested for pneumococci by means of quantitative polymerase chain reaction targeting the lytA and piaB genes, and we measured associations with SARS-CoV-2 infection using conditional logistic regression. RESULTS: Analyses included 1278 participants, with 564 enrolled in clinics and 714 enrolled through outreach-based testing. The prevalence of pneumococcal carriage was 9.2% (117 of 1278) among all participants (11.2% [63 of 564] in clinic-based testing and 7.6% [54 of 714] in outreach-based testing). The prevalence of SARS-CoV-2 infection was 27.4% (32 of 117) among pneumococcal carriers and 9.6% (112 of 1161) among noncarriers (adjusted odds ratio [aOR], 2.73 [95% confidence interval (CI): 1.58-4.69). Associations between SARS-CoV-2 infection and pneumococcal carriage were enhanced in the clinic-based sample (aOR, 4.01 [95% CI: 2.08-7.75]) and among symptomatic participants (3.38 [1.35-8.40]), compared with findings within the outreach-based sample and among asymptomatic participants. The adjusted odds of SARS-CoV-2 coinfection increased 1.24-fold (95% CI: 1.00-1.55-fold) for each 1-unit decrease in piaB quantitative polymerase chain reaction cycle threshold value among pneumococcal carriers. Finally, pneumococcal carriage modified the association of SARS-CoV-2 infection with recent exposure to a suspected coronavirus disease 2019 case (aOR, 7.64 [95% CI: 1.91-30.7] and 3.29 [1.94-5.59]) among pneumococcal carriers and noncarriers, respectively). CONCLUSIONS: Associations of pneumococcal carriage detection and density with SARS-CoV-2 suggest a synergistic relationship in the upper airway. Longitudinal studies are needed to determine interaction mechanisms between pneumococci and SARS-CoV-2.


Assuntos
COVID-19 , Infecções Pneumocócicas , Humanos , Adulto , Streptococcus pneumoniae/genética , COVID-19/epidemiologia , Infecções Pneumocócicas/epidemiologia , Infecções Pneumocócicas/microbiologia , Nasofaringe/microbiologia , SARS-CoV-2
2.
J Am Chem Soc ; 145(10): 5960-5969, 2023 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-36857421

RESUMO

We present a versatile method for the preparation of hyperpolarized [1-13C]fumarate as a contrast agent for preclinical in vivo MRI, using parahydrogen-induced polarization (PHIP). To benchmark this process, we compared a prototype PHIP polarizer to a state-of-the-art dissolution dynamic nuclear polarization (d-DNP) system. We found comparable polarization, volume, and concentration levels of the prepared solutions, while the preparation effort is significantly lower for the PHIP process, which can provide a preclinical dose every 10 min, opposed to around 90 min for d-DNP systems. With our approach, a 100 mM [1-13C]-fumarate solution of volumes up to 3 mL with 13-20% 13C-hyperpolarization after purification can be produced. The purified solution has a physiological pH, while the catalyst, the reaction side products, and the precursor material concentrations are reduced to nontoxic levels, as confirmed in a panel of cytotoxicity studies. The in vivo usage of the hyperpolarized fumarate as a perfusion agent in healthy mice and the metabolic conversion of fumarate to malate in tumor-bearing mice developing regions with necrotic cell death is demonstrated. Furthermore, we present a one-step synthesis to produce the 13C-labeled precursor for the hydrogenation reaction with high yield, starting from 13CO2 as a cost-effective source for 13C-labeled compounds.


Assuntos
Fumaratos , Imageamento por Ressonância Magnética , Camundongos , Animais , Espectroscopia de Ressonância Magnética , Imageamento por Ressonância Magnética/métodos , Hidrogenação , Meios de Contraste
3.
J Phys Chem A ; 127(16): 3728-3735, 2023 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-37053031

RESUMO

There is a fundamental issue with the use of dynamic nuclear polarization (DNP) to enhance nuclear spin polarization: the same polarizing agent (PA) needed for DNP is also responsible for shortening the lifetime of the hyperpolarization. As a result, long-term storage and transport of hyperpolarized samples is severely restricted and the apparatus for DNP is necessarily located near or integrated with the apparatus using the hyperpolarized spins. In this paper, we demonstrate that naphthalene single crystals can serve as a long-lived reservoir of proton polarization that can be exploited to enhance signals in benchtop and high-field NMR of target molecules in solution at a site 300 km away by a factor of several thousand. The naphthalene protons are polarized using short-lived optically excited triplet states of pentacene instead of stable radicals. In the absence of optical excitation, the electron spins remain in a singlet ground state, eliminating the major pathway of nuclear spin-lattice relaxation. The polarization decays with a time constant of about 50 h at 80 K and 0.5 T or above 800 h at 5 K and 20 mT. A module based on a Halbach array yielding a field of 0.75 T and a conventional cryogenic dry shipper, operating at liquid nitrogen temperature, allows storage and long distance transport of the polarization to a remote laboratory, where the polarization of the crystal is transferred after dissolution to a target molecule of choice by intermolecular cross-relaxation. The procedure has been executed repeatedly and has proven to be reliable and robust.

4.
Colorectal Dis ; 25(2): 315-325, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36238969

RESUMO

BACKGROUND: Preoperative absolute and functional iron deficiency anaemia is associated with poor postoperative outcomes in patients undergoing surgery for colorectal cancer. It is biologically plausible that "early", or "nonanaemic" iron deficiency may also be associated with worse postoperative outcomes in similar cohorts, albeit at lesser severity than that seen for anaemia. The evidence supporting this assertion is of low quality. METHODS: We have designed a prospective, observational study to delineate associations between preoperative non-anaemic iron deficiency and postoperative outcomes after surgery for colorectal cancer. Patients without anaemia, undergoing elective surgery for colorectal cancer will be allocated to an iron replete or an iron deficient group based on preoperative transferrin saturation. The primary outcome is days alive and at home on postoperative day 90. Secondary outcomes include days alive and at home on postoperative day 30, length of hospital stay, readmission to acute care, postoperative complications, health-related quality of life scores, quality of postoperative recovery, and requirement for allogeneic blood transfusion. The planned sample size is 422 patients, which has 80% power to detect a two-day difference in the primary outcome. The study commenced in May 2019. CONCLUSION: The results of this study will provide patients and clinicians with high-quality evidence concerning associations between nonanaemic iron deficiency and patient-centred outcomes after surgery for colorectal cancer. The study will be conducted in multiple urban and rural centres across Australia and New Zealand. The results will be highly generalisable to contemporary surgical practice and should be rapidly translated.


Assuntos
Anemia Ferropriva , Anemia , Neoplasias Colorretais , Deficiências de Ferro , Humanos , Estudos Prospectivos , Qualidade de Vida , Cuidados Pré-Operatórios/métodos , Ferro , Anemia Ferropriva/complicações , Anemia/complicações , Complicações Pós-Operatórias , Neoplasias Colorretais/cirurgia , Estudos Observacionais como Assunto , Estudos Multicêntricos como Assunto
5.
Angew Chem Int Ed Engl ; 62(50): e202312302, 2023 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-37837321

RESUMO

The HYPNOESYS method (Hyperpolarized NOE System), which relies on the dissolution of optically polarized crystals, has recently emerged as a promising approach to enhance the sensitivity of NMR spectroscopy in the solution state. However, HYPNOESYS is a single-shot method that is not generally compatible with multidimensional NMR. Here we show that 2D NMR spectra can be obtained from HYPNOESYS-polarized samples, using single-scan acquisition methods. The approach is illustrated with a mixture of terpene molecules and a benchtop NMR spectrometer, paving the way to a sensitive, information-rich and affordable analytical method.

6.
J Am Chem Soc ; 144(6): 2511-2519, 2022 02 16.
Artigo em Inglês | MEDLINE | ID: mdl-35113568

RESUMO

Nuclear spin hyperpolarization provides a promising route to overcome the challenges imposed by the limited sensitivity of nuclear magnetic resonance. Here we demonstrate that dissolution of spin-polarized pentacene-doped naphthalene crystals enables transfer of polarization to target molecules via intermolecular cross-relaxation at room temperature and moderate magnetic fields (1.45 T). This makes it possible to exploit the high spin polarization of optically polarized crystals, while mitigating the challenges of its transfer to external nuclei. With this method, we inject the highly polarized mixture into a benchtop NMR spectrometer and observe the polarization dynamics for target 1H nuclei. Although the spectra are radiation damped due to the high naphthalene magnetization, we describe a procedure to process the data to obtain more conventional NMR spectra and extract the target nuclei polarization. With the entire process occurring on a time scale of 1 min, we observe NMR signals enhanced by factors between -200 and -1730 at 1.45 T for a range of small molecules.

7.
J Neurosci ; 39(4): 596-611, 2019 01 23.
Artigo em Inglês | MEDLINE | ID: mdl-30504282

RESUMO

Neurons operate within defined activity limits, and feedback control mechanisms dynamically tune ionic currents to maintain this optimal range. This study describes a novel, rapid feedback mechanism that uses SUMOylation to continuously adjust ionic current densities according to changes in activity. Small ubiquitin-like modifier (SUMO) is a peptide that can be post-translationally conjugated to ion channels to influence their surface expression and biophysical properties. Neuronal activity can regulate the extent of protein SUMOylation. This study on the single, unambiguously identifiable lateral pyloric neuron (LP), a component of the pyloric network in the stomatogastric nervous system of male and female spiny lobsters (Panulirus interruptus), focused on dynamic SUMOylation in the context of activity homeostasis. There were four major findings: First, neuronal activity adjusted the balance between SUMO conjugation and deconjugation to continuously and bidirectionally fine-tune the densities of two opposing conductances: the hyperpolarization activated current (Ih) and the transient potassium current (IA). Second, tonic 5 nm dopamine (DA) gated activity-dependent SUMOylation to permit and prevent activity-dependent regulation of Ih and IA, respectively. Third, DA-gated, activity-dependent SUMOylation contributed to a feedback mechanism that restored the timing and duration of LP activity during prolonged modulation by 5 µm DA, which initially altered these and other activity features. Fourth, DA modulatory and metamoduatory (gating) effects were tailored to simultaneously alter and stabilize neuronal output. Our findings suggest that modulatory tone may select a subset of rapid activity-dependent mechanisms from a larger menu to achieve homeostasis under varying conditions.SIGNIFICANCE STATEMENT Post-translational SUMOylation of ion channel subunits controls their interactions. When subunit SUMOylation is dysregulated, conductance densities mediated by the channels are distorted, leading to nervous system disorders, such as seizures and chronic pain. Regulation of ion channel SUMOylation is poorly understood. This study demonstrated that neuronal activity can regulate SUMOylation to reconfigure ionic current densities over minutes, and this regulation was gated by tonic nanomolar dopamine. Dynamic SUMOylation was necessary to maintain specific aspects of neuronal output while the neuron was being modulated by high (5 µm) concentrations of dopamine, suggesting that the gating function may ensure neuronal homeostasis during extrinsic modulation of a circuit.


Assuntos
Homeostase/fisiologia , Canais Iônicos/fisiologia , Palinuridae/fisiologia , Sumoilação/fisiologia , Animais , Dopamina/fisiologia , Feminino , Gânglios dos Invertebrados/fisiologia , Células HEK293 , Humanos , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/metabolismo , Ativação do Canal Iônico/fisiologia , Masculino , Potenciais da Membrana/fisiologia , Neurônios/metabolismo , Processamento de Proteína Pós-Traducional , Canais de Potássio Shal/fisiologia
8.
Nutr Clin Pract ; 39(1): 129-140, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37840401

RESUMO

Chronic pancreatitis (CP) is often associated with exocrine pancreatic insufficiency (EPI), which may increase risk for fat-soluble vitamin depletion. Although vitamin D deficiency is widespread among the general population, vitamins A, E, and K deficiencies may more uniquely present in patients with CP. Yet, it is unclear whether fat-soluble vitamin status should be routinely monitored in all patients with CP or limited to those with EPI. The purpose of this review is to describe the laboratory status of vitamins A, E, and K in adult patients with CP and their association with exocrine pancreatic function. Five primary, observational studies met the inclusion criteria for qualitative synthesis. Biochemical deficiencies in fat-soluble vitamins were observed across trials but results varied with respect to whether EPI increased risk. Challenges related to the diagnosis and treatment of EPI along with potential confounders may contribute to the heterogeneity among study results. Although more studies are needed to determine the influence of pancreatic enzyme replacement therapy on fat-soluble vitamin status as well as effective vitamin repletion strategies, clinicians should consider periodically screening for deficiencies in all patients with CP regardless of EPI to avoid associated health effects of vitamin depletion.


Assuntos
Deficiência de Vitaminas , Insuficiência Pancreática Exócrina , Pancreatite Crônica , Adulto , Humanos , Vitaminas/uso terapêutico , Pancreatite Crônica/complicações , Insuficiência Pancreática Exócrina/etiologia , Insuficiência Pancreática Exócrina/complicações , Pâncreas , Deficiência de Vitaminas/complicações , Deficiência de Vitaminas/diagnóstico , Deficiência de Vitaminas/epidemiologia , Vitamina A , Vitamina K/uso terapêutico
9.
Nutr Clin Pract ; 39(2): 356-365, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38030578

RESUMO

High-dose vitamin B12 is a potential treatment for patients with vasodilatory shock that is refractory to other therapies. Vasodilatory shock is characterized by low blood pressure and low systemic vascular resistance. Nitric oxide and hydrogen sulfide, two potential targets of high-dose vitamin B12 given as hydroxocobalamin, facilitate this syndrome. This review explores the relationship between high-dose vitamin B12 and hemodynamic outcomes in adults with vasodilatory shock and provides an update on the literature since a 2019 review on this topic. A literature search of studies published in the past 5 years was conducted in the CINAHL, PubMed, Cochrane, and EMBASE databases in May 2023. After assessing for eligibility, eight studies met this review's inclusion criteria. Seven of the eight studies reported decreased vasopressor requirements for part or all of the study samples after receiving a hydroxocobalamin infusion. However, not all patients responded to hydroxocobalamin. These findings are limited by patient selection and differences in the timing of vasopressor requirement and blood pressure outcome assessments. The current evidence is promising as to whether vitamin B12 , given as a hydroxocobalamin infusion, may improve hemodynamic outcomes in vasodilatory shock, but the evidence is of low quality. The use of hydroxocobalamin to treat refractory, vasodilatory shock remains investigative. Larger randomized controlled trials are required to elucidate the role of vitamin B12 in treating refractory, vasodilatory shock, including in conjunction with other alternative therapies such as methylene blue and corticosteroids.


Assuntos
Choque , Vitamina B 12 , Adulto , Humanos , Vitamina B 12/uso terapêutico , Hidroxocobalamina/uso terapêutico , Choque/tratamento farmacológico , Vasoconstritores/uso terapêutico , Vitaminas/uso terapêutico
10.
PLoS One ; 19(1): e0291393, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38289939

RESUMO

Thermal performance curves (TPCs) depict variation in vital rates in response to temperature and have been an important tool to understand ecological and evolutionary constraints on the thermal sensitivity of ectotherms. TPCs allow for the calculation of indicators of thermal tolerance, such as minimum, optimum, and maximum temperatures that allow for a given metabolic function. However, these indicators are computed using only responses from surviving individuals, which can lead to underestimation of deleterious effects of thermal stress, particularly at high temperatures. Here, we advocate for an integrative framework for assessing thermal sensitivity, which combines both vital rates and survival probabilities, and focuses on the temperature interval that allows for population persistence. Using a collated data set of Lepidopteran development rate and survival measured on the same individuals, we show that development rate is generally limiting at low temperatures, while survival is limiting at high temperatures. We also uncover differences between life stages and across latitudes, with extended survival at lower temperatures in temperate regions. Our combined performance metric demonstrates similar thermal breadth in temperate and tropical individuals, an effect that only emerges from integration of both development and survival trends. We discuss the benefits of using this framework in future predictive and management contexts.


Assuntos
Temperatura Baixa , Insetos , Humanos , Animais , Temperatura
11.
Ann Surg Oncol ; 20(8): 2600-6, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23515911

RESUMO

BACKGROUND: Whereas guidelines supporting breast MRI in high-risk screening exist, guidelines for MRI use in newly diagnosed breast cancer are lacking. We, therefore, conducted a study of breast surgeons to determine practice beliefs surrounding MRI use in newly diagnosed breast cancer. METHODS: A survey sent to 2,274 American Society of Breast Surgeons members in December 2010 queried routine MRI use (defined as >75 % of time) in specific clinical scenarios. Analyses were performed by respondent practice setting, practice volume, and practice specialization. Descriptive statistics and subgroup analysis using a χ(2) and logistic regression were used. RESULTS: Responses from 1,012 surgeons (45.5 % response rate) were eligible for analysis. Respondents represented diverse practice settings (20 % academic, 72 % private practice) and volume (≤50 new breast cancer patients, 36 %; 51-100, 26 %; 101-200, 25 %; >200, 13 %). Also, 41 % of surgeons indicated routine MRI use for newly diagnosed patients, with higher rates of use among surgeons from high-volume practices, high specialization, and private practice. Greater consensus in routine MRI use was seen in the setting of extreme mammographic density (87.9 %), strong family history of breast cancer (73.4 %), and invasive lobular carcinoma (69.4 %). Responses were increasingly discordant in setting of pursuing breast conservation (47.4 %), invasive ductal carcinoma (41.8 %), and ductal carcinoma in situ (37.2 %). Personal experience was the most commonly cited influence on MRI use. CONCLUSIONS: Divergent responses in MRI use in newly diagnosed breast cancer reflect clinical uncertainty and variable practice beliefs among breast surgeons. Such diverging practice patterns highlight areas where clinical research and guidelines may be most helpful.


Assuntos
Neoplasias da Mama/diagnóstico , Carcinoma/diagnóstico , Imageamento por Ressonância Magnética/estatística & dados numéricos , Padrões de Prática Médica , Especialização/estatística & dados numéricos , Densidade da Mama , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/genética , Carcinoma/diagnóstico por imagem , Carcinoma/genética , Distribuição de Qui-Quadrado , Coleta de Dados , Feminino , Humanos , Prática Institucional/estatística & dados numéricos , Modelos Logísticos , Glândulas Mamárias Humanas/anormalidades , Prática Privada/estatística & dados numéricos , Radiografia
12.
Exp Cell Res ; 318(4): 416-23, 2012 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-22185824

RESUMO

After more than a decade of extensive experimentation, the promise of stem cells to revolutionize the field of medicine has negotiated their entry into clinical trial. Adipose tissue specifically holds potential as an attainable and abundant source of stem cells. Currently undergoing investigation are adipose stem cell (ASC) therapies for diabetes and critical limb ischemia, among others. In the enthusiastic pursuit of regenerative therapies, however, questions remain regarding ASC persistence and migration, and, importantly, their safety and potential for neoplasia. To date, assays of in vivo ASC activity have been limited by early end points. We hypothesized that with time, ASCs injected subcutaneously undergo removal by normal tissue turnover and homeostasis, and by the host's immune system. In this study, a high dose of culture expanded ASCs was formulated and implanted as multicellular aggregates into immunocompromised mice, which were maintained for over one year. Animals were monitored for toxicity, and surviving cells quantified at study endpoint. No difference in growth/weight or lifespan was found between cell-treated and vehicle treated animals, and no malignancies were detected in treated animals. Moreover, real-time PCR for a human specific sequence, ERV-3, detected no persistent ASCs. With the advent of clinical application, clarification of currently enigmatic stem cell properties has become imperative. Our study represents the longest duration determination of stem cell activity in vivo, and contributes strong evidence in support of the safety of adipose derived stem cell applications.


Assuntos
Tecido Adiposo/citologia , Células-Tronco Adultas/fisiologia , Transformação Celular Neoplásica , Células Estromais/fisiologia , Células-Tronco Adultas/citologia , Células-Tronco Adultas/patologia , Animais , Transformação Celular Neoplásica/patologia , Células Cultivadas , Criopreservação/métodos , Humanos , Camundongos , Camundongos Nus , Cultura Primária de Células/métodos , Células Estromais/citologia , Células Estromais/patologia , Análise de Sobrevida , Fatores de Tempo , Preservação de Tecido/métodos , Transplante Heterólogo , Ensaio Tumoral de Célula-Tronco
13.
Front Insect Sci ; 3: 1237624, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38469516

RESUMO

The interaction between larval host plant quality and temperature can influence the short-term physiological rates and life-history traits of insect herbivores. These factors can vary locally, resulting in local adaptation in responses to diet and temperature, but the comparison of these interactions between populations is infrequently carried out. In this study, we examine how the macronutrient ratio of an artificial diet determines the larval growth, development, and survival of larval Pieris rapae (Lepidoptera: Pieridae) at different temperatures between two invasive North American populations from different climatic regions. We conducted a fully factorial experiment with three temperature treatments (18°C, 25°C, and 32°C) and three artificial diet treatments varying in terms of the ratio of protein to carbohydrate (low protein, balanced, and high protein). The effects of diet on life-history traits were greater at lower temperatures, but these differed between populations. Larvae from the subtropical population had reduced survival to pupation on the low-protein diet in the cold temperature treatment, whereas larval survival for the temperate population was equally high for all temperature and diet treatments. Overall, both populations performed more poorly (i.e., they showed slower rates of consumption, growth, and development, and had a smaller pupal mass) in the diet with the low protein ratio, but larvae from the temperate population were less sensitive to diet ratio changes at all temperatures. Our results confirm that the physiological and life-history consequences of imbalanced nutrition for insect herbivores may depend on developmental temperatures, and that different geographic populations of P. rapae within North America vary in their sensitivity to nutritional balance and temperature.

14.
Ecol Evol ; 13(2): e9848, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36844672

RESUMO

Feeding for most animals involves bouts of active ingestion alternating with bouts of no ingestion. In insects, the temporal patterning of bouts varies widely with resource quality and is known to affect growth, development time, and fitness. However, the precise impacts of resource quality and feeding behavior on insect life history traits are poorly understood. To explore and better understand the connections between feeding behavior, resource quality, and insect life history traits, we combined laboratory experiments with a recently proposed mechanistic model of insect growth and development for a larval herbivore, Manduca sexta. We ran feeding trials for 4th and 5th instar larvae across different diet types (two hostplants and artificial diet) and used these data to parameterize a joint model of age and mass at maturity that incorporates both insect feeding behavior and hormonal activity. We found that the estimated durations of both feeding and nonfeeding bouts were significantly shorter on low-quality than on high-quality diets. We then explored how well the fitted model predicted historical out-of-sample data on age and mass of M. sexta. We found that the model accurately described qualitative outcomes for the out-of-sample data, notably that a low-quality diet results in reduced mass and later age at maturity compared with high-quality diets. Our results clearly demonstrate the importance of diet quality on multiple components of insect feeding behavior (feeding and nonfeeding) and partially validate a joint model of insect life history. We discuss the implications of these findings with respect to insect herbivory and discuss ways in which our model could be improved or extended to other systems.

15.
J Phys Chem Lett ; 14(8): 2125-2132, 2023 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-36802642

RESUMO

Magnetic resonance imaging of 13C-labeled metabolites enhanced by parahydrogen-induced polarization (PHIP) enables real-time monitoring of processes within the body. We introduce a robust, easily implementable technique for transferring parahydrogen-derived singlet order into 13C magnetization using adiabatic radio frequency sweeps at microtesla fields. We experimentally demonstrate the applicability of this technique to several molecules, including some molecules relevant for metabolic imaging, where we show significant improvements in the achievable polarization, in some cases reaching above 60% nuclear spin polarization. Furthermore, we introduce a site-selective deuteration scheme, where deuterium is included in the coupling network of a pyruvate ester to enhance the efficiency of the polarization transfer. These improvements are enabled by the fact that the transfer protocol avoids relaxation induced by strongly coupled quadrupolar nuclei.

16.
J Am Chem Soc ; 134(11): 5165-72, 2012 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-22364257

RESUMO

Halogen bonding (R-X···Y) is a qualitative analogue of hydrogen bonding that may prove useful in the rational design of artificial proteins and nucleotides. We explore halogen-bonded DNA base pairs containing modified guanine, cytosine, adenine and thymine nucleosides. The structures and stabilities of the halogenated systems are compared to the normal hydrogen bonded base pairs. In most cases, energetically stable, coplanar structures are identified. In the most favorable cases, halogenated base pair stabilities are within 2 kcal mol(-1) of the hydrogen bonded analogues. Among the halogens X = Cl, Br, and I, bromine is best suited for inclusion in these biological systems because it possesses the best combination of polarizability and steric suitability. We find that the most stable structures result from a single substitution of a hydrogen bond for a halogen bond in dA:dT and dG:dC base pairs, which allows 1 or 2 hydrogen bonds, respectively, to complement the halogen bond.


Assuntos
DNA/química , Halogênios/química , Pareamento de Bases , Sítios de Ligação , Ligação de Hidrogênio , Teoria Quântica
17.
Nutr Clin Pract ; 37(1): 68-80, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33734480

RESUMO

Hyperglycemia is associated with increased morbidity and mortality. Low-carbohydrate, high-fat (LCHF) enteral formulas are marketed to improve glycemic control; however, given the multifactorial mechanisms contributing to hyperglycemia in patients who are critically ill, the effect that LCHF formulas may have on improving glycemic control in this patient population is unclear. Current guidelines for the use of LCHF formulas among patients who are critically ill are limited by a lack of evidence. This review explores recent research published in the past 7 years to determine whether LCHF enteral formulas improve glycemic control compared with standard enteral formulas in patients who are critically ill. Four randomized controlled trials met the inclusion criteria for this review. Their results suggest that LCHF formulas may improve glycemic control in patients who are critically ill with diabetes mellitus and/or who are hyperglycemic. Further large-scale randomized controlled trials are warranted to validate these findings among different subgroups of patients with critical illness. The potential benefits of LCHF formulas need to be weighed against specific limitations, including that LCHF formulas typically do not contain sufficient protein to meet the recommended needs of patients who are critically ill.


Assuntos
Estado Terminal , Hiperglicemia , Carboidratos , Estado Terminal/terapia , Nutrição Enteral , Controle Glicêmico , Humanos , Hiperglicemia/prevenção & controle , Ensaios Clínicos Controlados Aleatórios como Assunto
18.
Nutr Clin Pract ; 37(2): 328-343, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34648201

RESUMO

Medical stabilization, nutrition rehabilitation, and weight restoration, while minimizing risk for the potentially fatal complication of refeeding syndrome, are the primary goals for the treatment of hospitalized individuals with anorexia nervosa and other restrictive-type eating disorders. The purpose of this review was to examine the literature exploring the prophylactic supplementation of phosphate, magnesium, and potassium, in addition to routine thiamin and multivitamin supplementation, for the prevention of refeeding syndrome in adolescents and adults with anorexia nervosa. Through evaluation of outcomes (including serum electrolyte levels and clinical signs and symptoms such as respiratory failure, cardiac failure, peripheral edema, rhabdomyolysis, and encephalopathy), three studies found that prophylactic supplementation of potassium, magnesium, and/or phosphate were effective in preventing refeeding syndrome or refeeding hypophosphatemia (a characteristic of refeeding syndrome). Although all studies found that prophylactic supplementation was effective in preventing refeeding syndrome, refeeding approaches (including the method, amount, and duration of nutrient delivery) as well as the populations studied varied considerably, making it difficult to arrive at specific recommendations for practice. Randomized controlled trials are needed to further examine the safety and effectiveness of prophylactic supplementation of phosphate, magnesium, and potassium on the prevention of refeeding syndrome, utilizing similar feeding and supplementation protocols.


Assuntos
Anorexia Nervosa , Hipofosfatemia , Síndrome da Realimentação , Adolescente , Adulto , Anorexia Nervosa/complicações , Anorexia Nervosa/terapia , Suplementos Nutricionais , Humanos , Hipofosfatemia/etiologia , Hipofosfatemia/prevenção & controle , Magnésio/uso terapêutico , Fosfatos , Potássio , Síndrome da Realimentação/etiologia , Síndrome da Realimentação/prevenção & controle
19.
ACS Omega ; 7(35): 31544-31550, 2022 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-36092615

RESUMO

Nanostructuring of a bulk material is used to change its mechanical, optical, and electronic properties and to enable many new applications. We present a scalable fabrication technique that enables the creation of densely packed diamond nanopillars for quantum technology applications. The process yields tunable feature sizes without the employment of lithographic techniques. High-aspect-ratio pillars are created through oxygen-plasma etching of diamond with a dewetted palladium film as an etch mask. We demonstrate an iterative renewal of the palladium etch mask, by which the initial mask thickness is not the limiting factor for the etch depth. Following the process, 300-400 million densely packed 100 nm wide and 1 µm tall diamond pillars were created on a 3 × 3 mm2 diamond sample. The fabrication technique is tailored specifically to enable applications and research involving quantum coherent defect center spins in diamond, such as nitrogen-vacancy (NV) centers, which are widely used in quantum science and engineering. To demonstrate the compatibility of our technique with quantum sensing, NV centers are created in the nanopillar sidewalls and are used to sense 1H nuclei in liquid wetting the nanostructured surface. This nanostructuring process is an important element for enabling the wide-scale implementation of NV-driven magnetic resonance imaging or NV-driven NMR.

20.
Health Soc Care Community ; 30(6): 2392-2403, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-35261102

RESUMO

The Healthy Eating, Active Living Matters (HEALing Matters) program is being scaled up across residential out-of-home care (OOHC) in Victoria, Australia and is providing young people with the knowledge, skills and resources to promote better health through healthy eating and activity. HEALing Matters was piloted as the HEAL program, a dual-intervention program that aimed to provide young people living in residential care with education and opportunities to improve their eating and physical activity habits, while simultaneously building the capacity of their carers to promote, encourage and role model healthy lifestyle behaviours. Qualitative findings indicated that HEAL resulted in increased participation in community sport, increased availability of sports equipment, healthy meal preparation and healthy food availability and improvements in perceived young person self-esteem and independent living skills. Findings also revealed some limitations of the program. Following the pilot, a participatory methodological approach was used to better understand how to align the HEAL program with individual and community needs. This approach engaged diverse stakeholders to better understand the barriers and enablers, address limitations, identify key intervention points and build trust and a shared vision to co-design the HEALing Matters program. HEALing Matters is now delivered within a framework that is informed by attachment, trauma and resilience theories. This paper outlines the HEALing Matters journey from what matters, to what works, to what translates in relation to a healthy eating and active living intervention in OOHC.


Assuntos
Estilo de Vida Saudável , Serviços de Assistência Domiciliar , Humanos , Adolescente , Dieta Saudável , Exercício Físico , Vitória
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA