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1.
Artigo em Inglês | MEDLINE | ID: mdl-32730191

RESUMO

INTRODUCTION: Three major classes of natural products (NPs) for medicinal purposes or improving wellbeing are generally available in the US: conventional drugs of herbal origin, botanical drugs, and dietary supplements (DSs). Consumer consumption of DSs is growing annually, with >50% of adults in the US taking dietary supplements. The US FDA regulates conventional and botanical drugs for safety and efficacy; however, DSs are minimally regulated. AREAS COVERED: This article will: i) highlight the importance of NP as a significant source of prescription drugs; ii) discuss differences in the regulation of conventional drugs of NP product, botanical drugs, and DSs; iii) discuss the safety and efficacy of DSs and iv) make recommendations for improvement of safety for minimally regulated NPs. The authors conducted a comprehensive literature search in two electronic databases, relevant NP and U.S. government websites for articles and regulatory documents published between January 1994 and April 2020. EXPERT OPINION: Toxicities associated with the use of NPs, including vitamins and DSs, are mainly due to excessive use and interactions with conventional drug(s) and may represent challenges for clinicians. Conventional and botanical-based prescription drugs are rarely associated with unknown toxicities. However, DSs are minimally regulated and can produce severe adverse effects. We believe that clinical pharmacologists can have a role in developing criteria for DS safety analysis. There is also the potential for a standardized NP stewardship program(s) and the development of NP policies and practices nationally and globally.

3.
Paediatr Drugs ; 22(3): 279-293, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32140997

RESUMO

Supplemental arginine has shown promise as a safe therapeutic option to improve endogenous nitric oxide (NO) regulation in cardiovascular diseases associated with endothelial dysfunction. In clinical studies in adults, L-arginine, an endogenous amino acid, was reported to improve cardiovascular function in hypertension, pulmonary hypertension, preeclampsia, angina, and MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) syndrome. L-citrulline, a natural precursor of L-arginine, is more bioavailable than L-arginine because it avoids hepatic first-pass metabolism and has a longer circulation time. Although not yet well-studied, arginine/citrulline has immense therapeutic potential in some life-threatening diseases in children. However, the optimal clinical development of arginine or citrulline in children requires more information about pharmacokinetics and exposure-response relationships at appropriate ages and under relevant disease states. This article summarizes the preclinical and clinical studies of arginine/citrulline in both adults and children, including currently available pharmacokinetic information. The pharmacology of arginine/citrulline is confounded by several patient-specific factors such as variations in baseline arginine/citrulline due to developmental ages and disease states. Currently available pharmacokinetic studies are insufficient to inform the optimal design of clinical studies, especially in children. Successful bench-to-bedside clinical translation of arginine supplementation awaits information from well-designed pharmacokinetic/pharmacodynamic studies, along with pharmacometric approaches.


Assuntos
Arginina/uso terapêutico , Citrulina/uso terapêutico , Farmacologia Clínica/métodos , Adolescente , Adulto , Arginina/farmacologia , Criança , Citrulina/farmacologia , Feminino , Humanos , Masculino , Adulto Jovem
4.
Ther Innov Regul Sci ; 53(5): 584-589, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31311309

RESUMO

Pediatric clinical trials are often requested according to specific age ranges. In the past and still today, these ages may correspond to developmental stages, such as newborn, infancy, childhood, and adolescence. Selection of ages for pediatric participation in medication studies should correspond to ages of rapid changes in pharmacokinetics and pharmacodynamics. Age-related changes in several enzymes involved in drug metabolism and glomerular filtration are described as examples of optimal ages for study of specific drugs according to their pathways of disposition.


Assuntos
Ensaios Clínicos como Assunto/métodos , Avaliação de Medicamentos/métodos , Adolescente , Distribuição por Idade , Fatores Etários , Criança , Pré-Escolar , Humanos , Lactente , Recém-Nascido , Farmacocinética
5.
Eur J Clin Pharmacol ; 75(1): 59-66, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30259065

RESUMO

PURPOSE: Intravenous (IV) magnesium sulfate (MgSO4) is clinically useful as adjunct therapy in treating acute asthma exacerbations. Despite its clinical utility, the disposition of magnesium in children is poorly described. The purpose of this study is to describe the pharmacokinetics (PK) of ionized and total serum magnesium following IV MgSO4 administration in children with severe acute asthma. METHODS: Thirty-two children receiving 50 mg/kg IV MgSO4 for acute asthma exacerbations at Primary Children's Hospital in Salt Lake City, UT, were prospectively enrolled in the study. Blood samples were collected before, as well as 30 min and 2 h after each child's IV MgSO4 dose, and used to determine total serum and ionized magnesium concentrations. The collected data were analyzed using population PK techniques using NONMEM® software. RESULTS: Total serum magnesium concentrations were used to externally validate our previously published model constructed with retrospective data (median prediction error 10.3%, median absolute prediction error 18.1%). The mean (%CV) observed endogenous ionized magnesium concentration was calculated to be 6.0 mg/L (12%), approximately one third of the same value for endogenous total serum magnesium (17.6 mg/L (22%)) in this dataset. Weight was a significant predictor of both clearance and volume in a population PK model describing ionized magnesium concentrations. No adverse events were observed in this pediatric cohort. CONCLUSIONS: This prospective study supports and extends our previous PK analysis of total serum magnesium concentrations. Ionized and total serum magnesium followed similar PK profiles following IV MgSO4 administration in children. A single bolus infusion of IV MgSO4 was safe in this small sample of children receiving it for acute asthma.


Assuntos
Antiasmáticos/administração & dosagem , Asma/tratamento farmacológico , Sulfato de Magnésio/administração & dosagem , Modelos Biológicos , Doença Aguda , Adolescente , Antiasmáticos/efeitos adversos , Antiasmáticos/farmacocinética , Asma/fisiopatologia , Criança , Pré-Escolar , Feminino , Hospitalização , Humanos , Infusões Intravenosas , Sulfato de Magnésio/efeitos adversos , Sulfato de Magnésio/farmacocinética , Masculino , Estudos Prospectivos , Índice de Gravidade de Doença , Fatores de Tempo
6.
Expert Opin Drug Metab Toxicol ; 13(9): 925-934, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28772091

RESUMO

INTRODUCTION: When in flight, pilots of high performance aircraft experience conditions unique to their profession. Training flights, performed as often as several times a week, can expose these pilots to altitudes in excess of 15 km (~50,000 ft, with a cabin pressurized to an altitude of ~20,000 ft), and the maneuvers performed in flight can exacerbate the G-forces felt by the pilot. While the pilots specifically train to withstand these extreme conditions, the physiologic stress could very likely lead to differences in the disposition of chemicals in the body, and consequently, dangerously high exposures. Unfortunately, very little is known about how the conditions experienced by fighter pilots affects chemical disposition. Areas covered: The purpose of this review is to present information about the effects of high altitude, G-forces, and other conditions experienced by fighter pilots on chemical disposition. Using this information, the expected changes in chemical exposure will be discussed, using isopropyl alcohol as an example. Expert opinion: There is a severe lack of information concerning the effects of the fighter pilot environment on the pharmacokinetics and pharmacodynamics of chemicals. Given the possibility of exposure prior to or during flight, it is important that these potential effects be investigated further.


Assuntos
Altitude , Doenças Profissionais/fisiopatologia , Pilotos , 2-Propanol/envenenamento , Aeronaves , Animais , Gravitação , Humanos , Exposição Ocupacional/efeitos adversos , Estresse Fisiológico/fisiologia
7.
Expert Rev Clin Pharmacol ; 10(11): 1203-1214, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28836870

RESUMO

INTRODUCTION: In the modern antimicrobial era, the rapid spread of resistance to antibiotics and introduction of new and mutating viruses is a global concern. Combating antimicrobial resistant microbes (AMR) requires coordinated international efforts that incorporate new conventional antibiotic development as well as development of alternative drugs with antimicrobial activity, management of existing antimicrobials, and rapid detection of AMR pathogens. Areas covered: This manuscript discusses some conventional strategies to control microbial resistance. The main purpose of the manuscript is to present information on specific herbal medicines that may serve as good treatment alternatives to conventional antimicrobials for infections sensitive to conventional as well as resistant strains of microorganisms. Expert commentary: Identification of potential new antimicrobials is challenging; however, one source for potential structurally diverse and complex antimicrobials are natural products. Natural products may have advantages over other post-germ theory antimicrobials. Many antimicrobial herbal medicines possess simultaneous antibacterial, antifungal, antiprotozoal and/or antiviral properties. Herbal products have the potential to boost host resistance to infections, particularly in immunocompromised patients. Antimicrobial broad-spectrum activity in conjunction with immunostimulatory properties may help to prevent microbial resistance to herbal medicine. As part of the efforts to broaden use of herbal medicines to treat microbial infections, pre-clinical and clinical testing guidelines of these compounds as a whole should be implemented to ensure consistency in formulation, efficacy and safety.


Assuntos
Anti-Infecciosos/administração & dosagem , Fitoterapia/métodos , Preparações de Plantas/administração & dosagem , Animais , Anti-Infecciosos/farmacologia , Desenho de Fármacos , Resistência Microbiana a Medicamentos , Humanos , Hospedeiro Imunocomprometido , Infecções/tratamento farmacológico , Infecções/microbiologia , Preparações de Plantas/farmacologia
8.
Eur J Clin Pharmacol ; 73(9): 1055-1069, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28600701

RESUMO

INTRODUCTION: Concerns with prescription antidepressant use in pregnant women have instigated the examination of potential associations between fetal exposure to antidepressant medication and outcomes including preterm delivery, congenital malformations, perinatal and post-natal adverse events, persistent pulmonary hypertension, and mortality. The retrospective cohort model is an often utilized study design. The objective of this review is to evaluate the literature on antidepressant use in pregnancy conducted as retrospective cohorts in national/regional medical, or claims databases that assess neonatal and infant outcomes for agreement between studies, ultimately providing a methodological and outcomes summary for future scientific endeavors. METHODS: PubMed was searched for literature relating to antidepressant use and infant outcomes from the earliest available date through July 15, 2016. Studies with a retrospective cohort design and conducted in national/regional medical or claims databases were included. Searched outcomes included preterm delivery, congenital malformations, low birth weight, small for gestational age, persistent pulmonary hypertension of the newborn, and other select adverse events comprising low Apgar score (5 min), convulsions/seizures, respiratory distress/problems, fetal mortality, and infant mortality. RESULTS: Of the 784 studies identified, 36 retrospective cohort studies met eligibility criteria. An increase in preterm delivery and respiratory distress/problems and no increase in congenital malformation or fetal and infant death were associated with prenatal use of prescription antidepressants by majority consensus (at least 2/3 [67%] of studies). CONCLUSIONS: While consensus indicates that perinatal prescription antidepressant use has consequences for the fetus and infant, there are notable inconsistencies in the literature. More investigations that address prenatal exposure to depression and other important covariates are needed.


Assuntos
Antidepressivos/efeitos adversos , Antidepressivos/uso terapêutico , Anormalidades Congênitas/epidemiologia , Bases de Dados Factuais , Feminino , Humanos , Hipertensão Pulmonar/epidemiologia , Recém-Nascido de Baixo Peso , Recém-Nascido , Trabalho de Parto Prematuro/epidemiologia , Gravidez , Transtornos Respiratórios/epidemiologia , Convulsões/epidemiologia
9.
Expert Rev Clin Pharmacol ; 10(3): 327-338, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27923318

RESUMO

INTRODUCTION: Herbal medicine (HM) use is growing worldwide. Single herb preparations, ethnic and modern HM formulations are widely used as adjunct therapies or to improve consumer wellbeing. Areas covered: This final part in the publication series summarizes common tendencies in HM use as adjunct or alternative medicine, education of healthcare professionals and consumers, current and proposed guidelines regulating of production. We discuss potential HM-HM and HM-drug interactions that could lead to severe adverse events in situations where HMs are taken without proper medical professional oversight. Expert commentary: A number of serious problems have arisen with the steady global increase in HM use. HM interaction with conventional drugs (CD) may result in inadequate dosing of CD or adverse reactions; HM-HM interaction within herbal supplements could lead to toxicity of formulations. Inadequate education of clinicians and patients regarding medicinal properties of HMs must be addressed regionally and globally to ensure consumer safety.


Assuntos
Terapias Complementares/métodos , Fitoterapia/métodos , Preparações de Plantas/uso terapêutico , Animais , Terapias Complementares/efeitos adversos , Terapias Complementares/tendências , Interações Ervas-Drogas , Humanos , Fitoterapia/efeitos adversos , Fitoterapia/tendências , Preparações de Plantas/efeitos adversos , Plantas Medicinais/química
10.
Expert Rev Clin Pharmacol ; 9(12): 1597-1609, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27644147

RESUMO

INTRODUCTION: Similar to other nations North American people used herbs for thousands of years to treat diseases and purify their spirits. By the middle of the 1900s, evidence-based conventional medicine received wide acceptance in Canada and the United States (US). Nowadays, people are going back to their roots and actively using herbal medicines (HMs) and natural health products (NHPs). Areas covered: This article is focusing on use and regulation of the HMs and NHPs in Canada and the US, raises concerns regarding HM and NHP safety and efficacy, offers suggestions on how to overcome these problems. Materials available from legislative and governmental websites, PubMed and news media were used. Expert commentary: Use of HMs, especially dietary supplements is widespread among adults in Canada and US. HMs and NHPs are regulated in both countries, but minimum criteria for product approval and post-market surveillance have been set. Concerns of quality, contamination, adulteration, and efficacy in are of central importance in the discussion of HMs and NHPs. Detailed product description and research are of vital importance to ensure safety and efficacy of these products. Additionally, 'herbal' education of healthcare providers and patients is needed to guarantee further successful integration of HM and conventional medicines.


Assuntos
Legislação de Medicamentos , Fitoterapia , Preparações de Plantas/uso terapêutico , Plantas Medicinais , Canadá , Humanos , Estados Unidos
11.
Anesth Analg ; 123(2): 382-93, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27331777

RESUMO

BACKGROUND: The endothelial glycocalyx is an important component of the vascular permeability barrier, forming a scaffold that allows serum proteins to create a gel-like layer on the endothelial surface and transmitting mechanosensing and mechanotransduction information that influences permeability. During acute inflammation, the glycocalyx is degraded, changing how it interacts with serum proteins and colloids used during resuscitation and altering its barrier properties and biomechanical characteristics. We quantified changes in the biomechanical properties of lung endothelial glycocalyx during control conditions and after degradation by hyaluronidase using biophysical techniques that can probe mechanics at (1) the aqueous/glycocalyx interface and (2) inside the glycocalyx. Our goal was to discern the location-specific effects of albumin and hydroxyethyl starch (HES) on glycocalyx function. METHODS: The effects of albumin and HES on the mechanical properties of bovine lung endothelial glycocalyx were studied using a combination of atomic force microscopy and reflectance interference contrast microscopy. Logistic regression was used to determine the odds ratios for comparing the effects of varying concentrations of albumin and HES on the glycocalyx with and without hyaluronidase. RESULTS: Atomic force microscopy measurements demonstrated that both 0.1% and 4% albumin increased the thickness and reduced the stiffness of glycocalyx when compared with 1% albumin. The effect of HES on glycocalyx thickness was similar to albumin, with thickness increasing significantly between 0.1% and 1% HES and a trend toward a softer glycocalyx at 4% HES. Reflectance interference contrast microscopy revealed a concentration-dependent softening of the glycocalyx in the presence of albumin, but a concentration-dependent increase in stiffness with HES. After glycocalyx degradation with hyaluronidase, stiffness was increased only at 4% albumin and 1% HES. CONCLUSIONS: Albumin and HES induced markedly different effects on glycocalyx mechanics and had notably different effects after glycocalyx degradation by hyaluronidase. We conclude that HES is not comparable with albumin for studies of vascular permeability and glycocalyx-dependent signaling. Characterizing the molecular and biomechanical effects of resuscitation colloids on the glycocalyx should clarify their indicated uses and permit a better understanding of how HES and albumin affect vascular function.


Assuntos
Células Endoteliais/efeitos dos fármacos , Glicocálix/efeitos dos fármacos , Derivados de Hidroxietil Amido/farmacologia , Pulmão/irrigação sanguínea , Substitutos do Plasma/farmacologia , Ressuscitação/métodos , Soroalbumina Bovina/farmacologia , Animais , Fenômenos Biomecânicos , Bovinos , Células Cultivadas , Distribuição de Qui-Quadrado , Coloides , Relação Dose-Resposta a Droga , Módulo de Elasticidade , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Glicocálix/metabolismo , Glicocálix/patologia , Hialuronoglucosaminidase/metabolismo , Modelos Logísticos , Microscopia de Força Atômica , Microscopia de Interferência , Razão de Chances
12.
Expert Rev Anti Infect Ther ; 14(8): 731-46, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27355512

RESUMO

INTRODUCTION: Voriconazole is a broad-spectrum antifungal agent commonly used to treat invasive fungal infections (IFI), including aspergillosis, candidiasis, Scedosporium infection, and Fusarium infection. IFI often occur in immunocompromised patients, leading to increased morbidity and mortality. AREAS COVERED: The objective of this review is to summarize the pharmacodynamic properties of voriconazole and to provide considerations for potential optimal dosing strategies. Studies have demonstrated superior clinical response when an AUC/MIC >25 or Cmin/MIC >1 is attained in adult patients, correlating to a trough concentration range as narrow as 2-4.5 mg/L; however, these targets are poorly established in the pediatric population. Topics in this discussion include voriconazole use in multiple age groups, predisposing patient factors for IFI, and considerations for clinicians managing IFI. Expert commentary: The relationship between voriconazole dosing and exposure is not well defined due to the large inter- and intra-subject variability. Development of comprehensive decision support tools for individualizing dosing, particularly in children who require higher dosing, will help to increase the probability of achieving therapeutic efficacy and decrease sub-therapeutic dosing and adverse events.


Assuntos
Antifúngicos/uso terapêutico , Infecções Fúngicas Invasivas/tratamento farmacológico , Voriconazol/uso terapêutico , Antifúngicos/administração & dosagem , Antifúngicos/farmacocinética , Antifúngicos/farmacologia , Área Sob a Curva , Relação Dose-Resposta a Droga , Predisposição Genética para Doença , Humanos , Infecções Fúngicas Invasivas/genética , Infecções Fúngicas Invasivas/imunologia , Infecções Fúngicas Invasivas/microbiologia , Testes de Sensibilidade Microbiana , Modelos Biológicos , Voriconazol/administração & dosagem , Voriconazol/farmacocinética , Voriconazol/farmacologia
13.
Expert Rev Clin Pharmacol ; 9(8): 1117-27, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27171366

RESUMO

INTRODUCTION: Herbal medicines (HMs) have been well known to people of the European Union (EU) and Russia for centuries. Currently, Western HMs can be classified into two categories, plant-derived conventional medicines and dietary supplements. Interest to HMs has grown rapidly in all countries during the past two decades. AREAS COVERED: The main goal of this review article is to present the history of HMs in the EU and Russia, forms of modern HMs, including Oriental Medicines that are popular among consumers of both countries. Additional discussion points comprise safety and adulteration issues associated with HMs, including regulatory changes and new legislative measures undertaken by the authorities. Materials available from legislative and governmental websites, PubMed and news media were used. Expert commentary: Due to cultural diversities in the EU and Russia, traditional HMs of other regions, particularly Chinese Traditional and Ayurvedic medicines, are also popular. Recently, dietary supplements containing multiple herbal and other natural products have flooded the EU and Russian markets. Pharmacovigilance in these markets is challenging in terms of establishing quality and safety of ingredients, determining efficacy, and defining risks of herb-herb and herb-drug interactions. Both the EU and Russia have introduced new legislation aimed to overcome these deficiencies.


Assuntos
Fitoterapia/métodos , Preparações de Plantas/uso terapêutico , Plantas Medicinais/química , Animais , Suplementos Nutricionais/efeitos adversos , Suplementos Nutricionais/normas , União Europeia , Interações Ervas-Drogas , Humanos , Legislação de Medicamentos , Medicina Tradicional/métodos , Preparações de Plantas/efeitos adversos , Preparações de Plantas/normas , Federação Russa
14.
Expert Rev Clin Pharmacol ; 9(9): 1225-33, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27232545

RESUMO

INTRODUCTION: Medicinal plants, and formulations prepared from them, have been used in China and Japan for thousands of years. Nowadays, ancient formulations of Traditional Chinese and Kampo (Japanese) Medicines coexist with Western herbal medicines (HMs) and complement each other. HMs are used for the treatment of mild and chronic diseases, as an adjunct therapy, to improve wellbeing and delay aging, or as healthy (functional) foods. AREAS COVERED: This article, a third part in a series of reviews, is focusing on history, use and regulation of the traditional and modern HMs in Japan and China. Materials available from legislative and governmental websites, PubMed and news media were used. Expert commentary: HMs are heavily regulated in both countries, often in a similar manner as conventional pharmaceutical drugs. The majority of herbal formulations are sold as over-the-counter medications supplied with leaflets describing indications and appropriate dosages for patients of different ages. Medical practitioners prescribe herbal formulations that are tailored to the needs of particular patients. Both countries had problems with adverse drug reactions and toxicity of single herbs and herbal formulations that have been investigated by authorities, and some drugs have been removed from the market.


Assuntos
Fitoterapia/métodos , Preparações de Plantas/uso terapêutico , Plantas Medicinais/química , China , Medicamentos de Ervas Chinesas/administração & dosagem , Medicamentos de Ervas Chinesas/efeitos adversos , Medicamentos de Ervas Chinesas/uso terapêutico , Humanos , Japão , Medicina Tradicional Chinesa/efeitos adversos , Medicina Tradicional Chinesa/métodos , Medicina Kampo/efeitos adversos , Medicina Kampo/métodos , Fitoterapia/efeitos adversos , Preparações de Plantas/administração & dosagem , Preparações de Plantas/efeitos adversos
15.
Am J Physiol Lung Cell Mol Physiol ; 302(12): L1242-9, 2012 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-22505668

RESUMO

Reflectance interference contrast microscopy (RICM) was used to study the mechanics of the endothelial glycocalyx. This technique tracks the vertical position of a glass microsphere probe that applies very light fluctuating loads to the outermost layer of the bovine lung microvascular endothelial cell (BLMVEC) glycocalyx. Fluctuations in probe vertical position are used to estimate the effective stiffness of the underlying layer. Stiffness was measured before and after removal of specific glycocalyx components. The mean stiffness of BLMVEC glycocalyx was found to be ~7.5 kT/nm(2) (or ~31 pN/nm). Enzymatic digestion of the glycocalyx with pronase or hyaluronan with hyaluronidase increased the mean effective stiffness of the glycocalyx; however, the increase of the mean stiffness on digestion of heparan sulfate with heparinase III was not significant. The results imply that hyaluronan chains act as a cushioning layer to distribute applied forces to the glycocalyx structure. Effective stiffness was also measured for the glycocalyx exposed to 0.1%, 1.0%, and 4.0% BSA; glycocalyx compliance increased at two extreme BSA concentrations. The RICM images indicated that glycocalyx thickness increases with BSA concentrations. Results demonstrate that RICM is sensitive to detect the subtle changes of glycocalyx compliance at the fluid-fiber interface.


Assuntos
Células Endoteliais/fisiologia , Glicocálix/metabolismo , Rigidez Vascular/efeitos dos fármacos , Animais , Bovinos , Células Cultivadas , Módulo de Elasticidade , Células Endoteliais/citologia , Glicocálix/efeitos dos fármacos , Heparitina Sulfato/metabolismo , Ácido Hialurônico/metabolismo , Hialuronoglucosaminidase/metabolismo , Pulmão/fisiologia , Microscopia de Interferência , Polissacarídeo-Liase/metabolismo , Pronase/metabolismo , Soroalbumina Bovina/farmacologia , Estresse Mecânico , Estresse Fisiológico/efeitos dos fármacos
16.
Am J Physiol Lung Cell Mol Physiol ; 301(3): L353-60, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21705487

RESUMO

The mechanical properties of endothelial glycocalyx were studied using atomic force microscopy with a silica bead (diameter ∼18 µm) serving as an indenter. Even at indentations of several hundred nanometers, the bead exerted very low compressive pressures on the bovine lung microvascular endothelial cell (BLMVEC) glycocalyx and allowed for an averaging of stiffness in the bead-cell contact area. The elastic modulus of BLMVEC glycocalyx was determined as a pointwise function of the indentation depth before and after enzymatic degradation of specific glycocalyx components. The modulus-indentation depth profiles showed the cells becoming progressively stiffer with increased indentation. Three different enzymes were used: heparinases III and I and hyaluronidase. The main effects of heparinase III and hyaluronidase enzymes were that the elastic modulus in the cell junction regions increased more rapidly with the indentation than in BLMVEC controls, and that the effective thickness of glycocalyx was reduced. Cytochalasin D abolished the modulus increase with the indentation. The confocal profiling of heparan sulfate and hyaluronan with atomic force microscopy indentation data demonstrated marked heterogeneity of the glycocalyx composition between cell junctions and nuclear regions.


Assuntos
Glicocálix/metabolismo , Animais , Bovinos , Citocalasina D/farmacologia , Elasticidade , Células Endoteliais/metabolismo , Glicocálix/ultraestrutura , Heparina Liase/metabolismo , Hialuronoglucosaminidase/metabolismo , Pulmão , Microscopia de Força Atômica , Polissacarídeo-Liase/metabolismo
17.
FEBS J ; 275(24): 6248-59, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19019076

RESUMO

An active site aspartate residue, Asp97, in the methionine aminopeptidase (MetAPs) from Escherichia coli (EcMetAP-I) was mutated to alanine, glutamate, and asparagine. Asp97 is the lone carboxylate residue bound to the crystallographically determined second metal-binding site in EcMetAP-I. These mutant EcMetAP-I enzymes have been kinetically and spectroscopically characterized. Inductively coupled plasma-atomic emission spectroscopy analysis revealed that 1.0 +/- 0.1 equivalents of cobalt were associated with each of the Asp97-mutated EcMetAP-Is. The effect on activity after altering Asp97 to alanine, glutamate or asparagine is, in general, due to a approximately 9000-fold decrease in k(ca) towards Met-Gly-Met-Met as compared to the wild-type enzyme. The Co(II) d-d spectra for wild-type, D97E and D97A EcMetAP-I exhibited very little difference in form, in each case, between the monocobalt(II) and dicobalt(II) EcMetAP-I, and only a doubling of intensity was observed upon addition of a second Co(II) ion. In contrast, the electronic absorption spectra of [Co_(D97N EcMetAP-I)] and [CoCo(D97N EcMetAP-I)] were distinct, as were the EPR spectra. On the basis of the observed molar absorptivities, the Co(II) ions binding to the D97E, D97A and D97N EcMetAP-I active sites are pentacoordinate. Combination of these data suggests that mutating the only nonbridging ligand in the second divalent metal-binding site in MetAPs to an alanine, which effectively removes the ability of the enzyme to form a dinuclear site, provides a MetAP enzyme that retains catalytic activity, albeit at extremely low levels. Although mononuclear MetAPs are active, the physiologically relevant form of the enzyme is probably dinuclear, given that the majority of the data reported to date are consistent with weak cooperative binding.


Assuntos
Aminopeptidases/química , Aminopeptidases/metabolismo , Ácido Aspártico , Escherichia coli/enzimologia , Alanina , Sequência de Aminoácidos , Substituição de Aminoácidos , Aminopeptidases/genética , Asparagina , Catálise , Domínio Catalítico , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Ácido Glutâmico , Glicina , Cinética , Metionina , Metionil Aminopeptidases , Modelos Moleculares , Conformação Molecular , Dados de Sequência Molecular , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Alinhamento de Sequência , Especificidade por Substrato
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