Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 75
Filtrar
Más filtros

Tipo del documento
Intervalo de año de publicación
1.
Appl Environ Microbiol ; 88(5): e0214921, 2022 03 08.
Artículo en Inglés | MEDLINE | ID: mdl-35020454

RESUMEN

Salmonella enterica can survive in surface waters (SuWa), and the role of nonhost environments in its transmission has acquired increasing relevance. In this study, we conducted comparative genomic analyses of 172 S. enterica isolates collected from SuWa across 3 months in six states of central Mexico during 2019. S. enterica transmission dynamics were assessed using 87 experimental and 112 public isolates from Mexico collected during 2002 through 2019. We also studied genetic relatedness between SuWa isolates and human clinical strains collected in North America during 2005 through 2020. Among experimental isolates, we identified 41 S. enterica serovars and 56 multilocus sequence types (STs). Predominant serovars were Senftenberg (n = 13), Meleagridis, Agona, and Newport (n = 12 each), Give (n = 10), Anatum (n = 8), Adelaide (n = 7), and Infantis, Mbandaka, Ohio, and Typhimurium (n = 6 each). We observed a high genetic diversity in the sample under study, as well as clonal dissemination of strains across distant regions. Some of these strains are epidemiologically important (ST14, ST45, ST118, ST132, ST198, and ST213) and were genotypically close to those involved in clinical cases in North America. Transmission network analysis suggests that SuWa are a relevant source of S. enterica (0.7 source/hub ratio) and contribute to its dissemination as isolates from varied sources and clinical cases have SuWa isolates as common ancestors. Overall, the study shows that SuWa act as reservoirs of various S. enterica serovars of public health significance. Further research is needed to better understand the mechanisms involved in SuWa contamination by S. enterica, as well as to develop interventions to contain its dissemination in food production settings. IMPORTANCE Surface waters are heavily used in food production worldwide. Several human pathogens can survive in these waters for long periods and disseminate to food production environments, contaminating our food supply. One of these pathogens is Salmonella enterica, a leading cause of foodborne infections, hospitalizations, and deaths in many countries. This research demonstrates the role of surface waters as a vehicle for the transmission of Salmonella along food production chains. It also shows that some strains circulating in surface waters are very similar to those implicated in human infections and harbor genes that confer resistance to multiple antibiotics, posing a risk to public health. This study contributes to expand our current knowledge on the ecology and epidemiology of Salmonella in surface waters.


Asunto(s)
Salmonella enterica , Agricultura , Acuicultura , Genómica , Humanos , México/epidemiología , Salmonella enterica/genética
2.
Neurosurg Rev ; 45(1): 411-419, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-34142268

RESUMEN

Brachial plexus injury is a lesion that results in loss of function of the arm, and there are multiple ways of surgically approaching its treatment. Controlled trials that compare all surgical repair strategies and their clinical outcomes have not been performed. A systematic review was conducted to identify all articles that reported clinical outcomes in different surgeries (nerve transfer, nerve graft, neurolysis, end-to-end, multiple interventions, and others). Advanced search in PubMed was performed using the Mesh terms "brachial plexus injury" as the main topic and "surgery" as a subtopic, obtaining a total of 2153 articles. The clinical data for eligibility extraction was focused on collecting motor, sensory, pain, and functional recovery. A statistical analysis was performed to find the superior surgical techniques in terms of motor recovery, through the assessment of heterogeneity between groups, and of relationships between surgery and motor recovery. The frequency and the manner in which clinical outcomes are recording were described. The differences that correspond to the demographics and procedural factors were not statistically significant among groups (p > 0.05). Neurolysis showed the highest proportion of motor recovery (85.18%), with significant results between preoperative and post-operative motor assessment (p = 0.028). The proportion of motor recovery in each group according to the surgical approach differed significantly (X2 = 82.495, p = 0.0001). The motor outcome was the most reported clinical outcome (97.56%), whereas the other clinical outcomes were reported in less than 15% of the included articles. Unexpectedly, neurolysis, a technique displaced by new surgical alternatives such as nerve transfer/graft, demonstrated the highest proportion of motor recovery. Clinical outcomes such as pain, sensory, and functional recovery were infrequently reported. These results introduce the need to re-evaluate neurolysis through comparative clinical trials, as well as to standardize the way in which clinical outcomes are reported.


Asunto(s)
Neuropatías del Plexo Braquial , Plexo Braquial , Transferencia de Nervios , Plexo Braquial/cirugía , Neuropatías del Plexo Braquial/cirugía , Humanos , Procedimientos Neuroquirúrgicos , Resultado del Tratamiento
3.
Ecotoxicol Environ Saf ; 130: 81-6, 2016 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-27085001

RESUMEN

Indium has numerous applications in different industrial sectors and is not an abundant element. Therefore appropriate technology to recover this element from various process wastes is needed. This research reports high adsorption capacity of multiwalled carbon nanotubes (MWCNT) for In(III). The effects of pH, kinetics, isotherms and adsorption mechanism of MWCNT on In(III) adsorption were investigated and discussed in detail. The pH increases improves the adsorption capacity for In(III). The Langmuir adsorption model is the best fit with the experimental data. For the kinetic study, the adsorption onto MWCNT could be fitted to pseudo second-order. The adsorption of indium(III) can be described to a mechanism which consists of a film diffusion controlled process. Metal desorption can be achieved with acidic solutions.


Asunto(s)
Indio/química , Nanotubos de Carbono/química , Adsorción , Concentración de Iones de Hidrógeno , Cinética , Soluciones , Temperatura , Purificación del Agua/métodos
4.
J Air Waste Manag Assoc ; 63(5): 534-44, 2013 May.
Artículo en Inglés | MEDLINE | ID: mdl-23786145

RESUMEN

UNLABELLED: The char produced in the thermolysis of granulated scrap tyres has few market outlets, reducing the economic viability of the thermolytic process. This paper reports the potential of this char as a low-cost precursor of porous carbons. The tyre-derived char was demineralized in either alkaline or acidic media to reduce its ash, zinc, sulfur, and silica contents. The lowest impurity content was achieved with an HNO3/H2O treatment. The resulting demineralized char was then subjected to activation by KOH or CO2. The Brunauer-Emmett-Teller (BET)-specific surface area of the activated carbon produced by the KOH treatment was 242 m2/g, whereas that of the CO2-activated carbon was 720 m2/g. The textural properties of the latter product were similar to those of some commercial activated carbons. The use of tyre-derived char as a precursor of porous carbons could render the thermolytic treatment of scrap tyres more economically attractive. IMPLICATIONS: Char produced in thermolysis of granulated scrap tyres has a few market outlets; in this paper an alternative for its use is presented. The char was converted into activated carbon with textural properties similar to those of some commercial activated carbons. This process could render the thermolytic treatment of scrap tyres more economically attractive.


Asunto(s)
Carbono/análisis , Carbono/química , Reciclaje/métodos , Eliminación de Residuos/métodos , Hollín/química , Automóviles , Calor , Residuos Industriales , Goma
6.
Phytother Res ; 23(5): 666-71, 2009 May.
Artículo en Inglés | MEDLINE | ID: mdl-19107855

RESUMEN

The aim of this study was to investigate the biodynamic effects of vulgarenol, a sesquiterpene isolated from Magnolia grandiflora flower petals and its possible mechanism on the Langendorff isolated and perfused heart model. Vulgarenol (5 microm) caused a statistically significant decrease in coronary vascular resistance (15.21 +/- 6.00 dyn s cm(-5) vs 36.80 +/- 5.01 dyn s cm(-5), control group), increased nitric oxide release (223.01 +/- 8.76 pmol/mL vs 61.00 +/- 12.00 pmol/mL, control group) and cyclic guanosine monophosphate accumulation in left ventricular tissue samples (142.17 +/- 8.41 pmol/mg of tissue vs 43.94 +/- 5.00 pmol/mg of tissue, control group). Pre-treatment with 3 microm gadolinium chloride hexahydrate, 100 microm N(omega)-nitro-L-arginine methyl ester hydrochloride, and 10 microm 1H-[1,2,4]oxadiazolo[4,2-a]quinoxalin-1-one significantly abolished the vulgarenol-induced coronary vascular resistance decrease, nitric oxide increased release and cGMP accumulation in left ventricular tissue samples. The results support the fact that nitric oxide and cyclic guanosine monophosphate are likely involved in the endothelium-dependent coronary vasodilation.


Asunto(s)
Circulación Coronaria/efectos de los fármacos , Magnolia/química , Sesquiterpenos/farmacología , Resistencia Vascular/efectos de los fármacos , Vasodilatadores/farmacología , Animales , GMP Cíclico/metabolismo , Flores/química , Cobayas , Técnicas In Vitro , Masculino , Miocardio/metabolismo , Óxido Nítrico/metabolismo , Extractos Vegetales/farmacología
7.
Phytother Res ; 23(7): 948-54, 2009 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-19153985

RESUMEN

Citrus paradisi (grapefruit) consumption is considered as beneficial and it is popularly used for the treatment of a vast array of diseases, including hypertension. In the present study, the coronary vasodilator and hypotensive effects of Citrus paradisi peel extract were assessed in the Langendorff isolated and perfused heart model and in the heart and lung dog preparation. In both models, Citrus paradisi peel extract decreased coronary vascular resistance and mean arterial pressure when compared with control values (60 +/- 15 x 10(7) dyn s cm(-5) vs 100 +/- 10 x 10(7) dyn s cm(-5) and 90 mmHg vs 130 +/- 15 mmHg, respectively). These decreases in coronary vascular resistance and mean arterial pressure were blocked when isolated and perfused hearts and mongrel dogs were pre-treated with L-NAME. In humans, Citrus paradisi juice decreased diastolic arterial pressure and systolic arterial pressure both in normotensive and hypertensive subjects. Citrus paradisi juice produced a greater decrease in mean arterial pressure when compared with Citrus sinensis juice, cow milk and a vitamin C-supplemented beverage. However, more detailed studies are required to isolate, purify and evaluate the chemical compounds responsible for this pharmacological effect and to clarify its possible role for treating hypertension.


Asunto(s)
Antihipertensivos/farmacología , Presión Sanguínea/efectos de los fármacos , Corazón/efectos de los fármacos , Extractos Vegetales/farmacología , Resistencia Vascular/efectos de los fármacos , Animales , Citrus paradisi/química , Perros , Femenino , Humanos , Hipertensión/tratamiento farmacológico , Pulmón/efectos de los fármacos , Masculino , NG-Nitroarginina Metil Éster/farmacología , Ratas , Ratas Wistar
8.
Sci Rep ; 9(1): 19933, 2019 Dec 27.
Artículo en Inglés | MEDLINE | ID: mdl-31882744

RESUMEN

We introduce the concept of degree of quantumness in quantum synchronization, a measure of the quantum nature of synchronization in quantum systems. Following techniques from quantum information, we propose the number of non-commuting observables that synchronize as a measure of quantumness. This figure of merit is compatible with already existing synchronization measurements, and it captures different physical properties. We illustrate it in a quantum system consisting of two weakly interacting cavity-qubit systems, which are coupled via the exchange of bosonic excitations between the cavities. Moreover, we study the synchronization of the expectation values of the Pauli operators and we propose a feasible superconducting circuit setup. Finally, we discuss the degree of quantumness in the synchronization between two quantum van der Pol oscillators.

9.
PLoS One ; 13(7): e0200455, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30024914

RESUMEN

We propose a protocol to perform quantum reinforcement learning with quantum technologies. At variance with recent results on quantum reinforcement learning with superconducting circuits, in our current protocol coherent feedback during the learning process is not required, enabling its implementation in a wide variety of quantum systems. We consider diverse possible scenarios for an agent, an environment, and a register that connects them, involving multiqubit and multilevel systems, as well as open-system dynamics. We finally propose possible implementations of this protocol in trapped ions and superconducting circuits. The field of quantum reinforcement learning with quantum technologies will enable enhanced quantum control, as well as more efficient machine learning calculations.


Asunto(s)
Aprendizaje Automático , Teoría Cuántica , Refuerzo en Psicología
10.
Transl Anim Sci ; 2(Suppl 1): S100, 2018 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32704751

RESUMEN

Crude glycerin (GLY) is used as an energy supplement for cattle and has been shown to increase propionate and decrease acetate concentrations in the rumen. Glycerin also decreases ruminal NH3, and therefore, we hypothesized that GLY in rumen fluid would decrease protein degradability of feedstuffs. The objective was to evaluate the effect of GLY in bovine rumen fluid on extent of protein degradability of alfalfa hay (ALF), dried distiller's grains (DDG), and soybean meal (SBM). The study was conducted using an in vitro incubator with four incubation jars. Each incubation jar contained 18 filter bags with 0.5 g of ground feed sample (six bags contained ALF, six contained DDG, and six contained SBM), six blank bags, 1,600 mL of buffer solution, 400-mL rumen fluid (collected from two ruminally cannulated cows), and one of the two treatments. Treatments were 12.7 g of deionized water (-GLY) or 12.7 g of GLY (+GLY) added to the 2-liter contents of each jar. Incubation jars were purged with CO2 and allowed to incubate at 39°C for 48 h. The 48-h incubation period was repeated for a total of three runs (the study was a randomized complete block design). Fluid samples from incubation jars were collected at 0 and 48 h into 25-mL vials for measurement of pH and analysis of VFA and NH3. At the end of the 48-h incubation period, filter bags containing feed samples were collected for determination of DM, NDF, and CP disappearance. The pH and NH3 concentrations of the contents of jars were lower (P ≤ 0.01) and total VFA concentrations were greater (P < 0.01) for +GLY than -GLY after 48 h of incubation. Molar percentages of acetate, isobutyrate, and isovalerate were lower (P < 0.01) and molar percentages of propionate and valerate were greater (P ≤ 0.02), resulting in a lower (P < 0.01) acetate-to-propionate ratio for +GLY compared with -GLY after the 48-h incubation period. A GLY × feed interaction (P < 0.01) occurred for DM and CP disappearance, where +GLY decreased DM and CP disappearance of SBM more than that of ALF and DDG. Disappearance of NDF from ALF, DDG, and SBM was lower for +GLY compared with -GLY (GLY; P < 0.01). These results suggest that supplementing glycerin to ruminants may cause an increase in RUP fraction escaping to the small intestine for potential digestion and absorption.

11.
Mater Sci Eng C Mater Biol Appl ; 72: 18-25, 2017 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-28024575

RESUMEN

In the field of bioabsorbable composites for biomedical applications, extrusion has been employed as a method to prepare homogeneous blends of polymeric matrices with bioactive ceramic fillers. In this work, the suitability of processing poly-l-lactic acid/Magnesium (PLLA/Mg) composites by hot extrusion has been assessed by a systematic characterization of PLLA/Mg composites containing different amounts of Mg particles up to 7wt%. The results show that extrusion causes a reduction of almost 20% in the viscosity average molecular weight of PLLA, which further decreases with increasing Mg content. Extrusion gave always rise to a homogeneous distribution of Mg particles within the PLLA matrix. This composite processing was not compromised by the degradation of the polymeric matrix because the processing temperature was always below the onset degradation temperature. In the processing conditions employed in the present work, degradation of the composite slightly increases as more Mg is added up to 5wt%, but is very high at 7wt%. This was also evident from the mechanical behaviour, so that Mg particles improved the stiffness and compression strength of neat PLLA until 5wt% of Mg content, which dropped drastically when the material had 7wt% of Mg. The filler strengthening factor decreases with the increment in Mg content. In order to obtain an optimised contribution of Mg particles, a balance between thermal degradation and mechanical resistance of PLLA must be achieved.


Asunto(s)
Magnesio/química , Poliésteres/química , Rastreo Diferencial de Calorimetría , Módulo de Elasticidad , Espectroscopía Infrarroja por Transformada de Fourier , Temperatura , Viscosidad
12.
Sci Rep ; 7: 44654, 2017 03 20.
Artículo en Inglés | MEDLINE | ID: mdl-28317916

RESUMEN

Classical to quantum decoherence transition, an issue existing for incoherent superposition of Bell-diagonal states is studied for three dimensional bipartite AB mixed quantum systems. Depending on the initial conditions, the dynamics of classical and quantum correlations can exhibit a sudden transition between classical to quantum decoherence. This result is calculated numerically by using entropic and geometric measures of correlations. An alternative explanation for this effect could be obtained by extending the bipartite A ⊗ B qutrit system to a pure tripartite A ⊗ B ⊗ C system. The freezing of classical correlations in AB is related to a freezing of the entanglement in the AC bipartition.

13.
Sci Rep ; 7(1): 4157, 2017 06 23.
Artículo en Inglés | MEDLINE | ID: mdl-28646203

RESUMEN

We study quantum state transfer between two qubits coupled to a common quantum bus that is constituted by an ultrastrong coupled light-matter system. By tuning both qubit frequencies on resonance with a forbidden transition in the mediating system, we demonstrate a high-fidelity swap operation even though the quantum bus is thermally populated. We discuss a possible physical implementation in a realistic circuit QED scheme that leads to the multimode Dicke model. This proposal may have applications on hot quantum information processing within the context of ultrastrong coupling regime of light-matter interaction.

14.
FEMS Microbiol Rev ; 14(4): 397-404, 1994 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-7917427

RESUMEN

This report looks at the laboratory-scale recovery of iron oxides (alpha Fe2O3 type) through bio-oxidation with Thiobacillus ferrooxidans of the ferrous sulphate contained in steel industry sulphuric pickling liquors. This is done by calcining iron sulphates and iron and ammonium sulphates obtained from the crystallization of the oxidized solution. The products of the bacterial reaction and the iron oxides are then studied according to calcination temperature. The process carried out produced 50 kg of alpha Fe2O3 per m3 of waste pickling liquor at 700 degrees C with 99.8% weight iron recovery.


Asunto(s)
Residuos Industriales , Sulfatos/metabolismo , Thiobacillus/metabolismo , Contaminantes Químicos del Agua/aislamiento & purificación , Compuestos Ferrosos/metabolismo , Oxidación-Reducción , Acero
15.
J Dev Orig Health Dis ; 7(3): 237-243, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-26490762

RESUMEN

In humans, obesity before and during pregnancy is associated with both fetal macrosomia and growth restriction, and long-term cardiovascular risk in the offspring. We aimed to determine whether overweighted pregnant guinea pig sows results in an increased fetal weight at term and the effects on the vascular reactivity in fetal systemic and umbilical arteries. Pregnant guinea pigs were classified as control (n=4) or high weight (HWS, n=5) according to their pre-mating weight, and their fetuses extracted at 0.9 gestation (~60 days). Segments of fetal femoral and umbilical arteries were mounted in a wire myograph, where the contractile response to KCl (5-125 mM), and the relaxation to nitric oxide synthase-dependent agents (insulin, 10-10-10-7 and acetylcholine, 10-10-10-5) and nitric oxide [sodium nitroprusside (SNP), 10-10-10-5] were determined. Fetuses from HWS (HWSF) were grouped according to their body weight as low (85 g) fetal weight, based on the confidence interval (76.5-84.9 g) of the control group. No HWSF were observed in the normal range. Umbilical arteries from HWSF showed a lower response to KCl and insulin compared with controls, but a comparable response with SNP. Conversely, femoral arteries from HWSF showed an increased response to KCl and acetylcholine, along with a decreased sensitivity to SNP. These data show that overweight sows have altered fetal growth along gestation. Further, large and small fetuses from obese guinea pig sows showed altered vascular reactivity at umbilical and systemic vessels, which potentially associates with long-term cardiovascular risk.

16.
Chest ; 106(5): 1563-9, 1994 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-7956419

RESUMEN

OBJECTIVES: The present study was designed to evaluate if continuous positive airway pressure (CPAP) augments the effect of nitric oxide (NO) inhalation on matching between ventilation and perfusion (VA/Q) during acute lung injury. DESIGN: Prospective, randomized study. SETTING: A research laboratory at a university medical center. SUBJECTS: Ten anesthetized mongrel dogs with oleic acid-induced lung injury. INTERVENTIONS: Zero or 40 parts per million of NO in the inspiratory gas, with and without 10 cm H2O CPAP in random order. MEASUREMENTS AND MAIN RESULTS: Gas exchange was assessed by estimating the VA/Q distributions using the multiple inert gas elimination technique. Application of CPAP decreased blood flow to shunt units by 26 +/- 2 percent (mean +/- SD) and increased the fraction of cardiac output to normal VA/Q units (VA/Q ratio of 0.1 to 10) by 26 +/- 2 percent (p < 0.05). Inhalation of NO during CPAP accounted for a further 10 +/- 2 percent decrease in the blood flow to shunt units and an 8 +/- 2 percent increase in the fraction of the cardiac output to normal VA/Q units (p < 0.05). Inhalation of NO alone had no significant effect on the VA/Q distributions. Inhalation of NO decreased mean transmural pulmonary artery pressure (Ppatm) both without (Ppatm from 30 +/- 2 to 23 +/- 2 mm Hg; PVR from 323 +/- 44 to 228 +/- 43 dynes.s .cm-5; p < 0.05) and with CPAP (Ppatm from 25 +/- 2 to 20 +/- 2 mm Hg; PVR from 255 +/- 30 to 173 +/- 31 dynes.s.cm-5; p < 0.05). CONCLUSIONS: Although pulmonary vascular resistance can be lowered with NO inhalation alone, recruitment of gas exchange units with CPAP is necessary to produce a beneficial effect of NO inhalation on VA/Q matching and oxygenation. When recruitment of gas exchange units with CPAP brings gaseous NO in contact with enough pulmonary blood vessels, NO-induced vasodilation will augment VA/Q matching by a steal mechanism.


Asunto(s)
Óxido Nítrico/administración & dosificación , Respiración con Presión Positiva , Síndrome de Dificultad Respiratoria/terapia , Relación Ventilacion-Perfusión/efectos de los fármacos , Administración por Inhalación , Análisis de Varianza , Animales , Análisis de los Gases de la Sangre , Perros , Hemodinámica/efectos de los fármacos , Modelos Lineales , Ácido Oléico , Ácidos Oléicos , Estudios Prospectivos , Distribución Aleatoria , Síndrome de Dificultad Respiratoria/sangre , Síndrome de Dificultad Respiratoria/inducido químicamente , Síndrome de Dificultad Respiratoria/fisiopatología
17.
J Heart Lung Transplant ; 17(3): 321-4, 1998 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-9563611

RESUMEN

We report a case of fatal central nervous system infection with Scedosporium apiospermum (Pseudallescheria boydii) in a heart transplant recipient. This ubiquitous fungus is known to cause mycetoma and localized infections in patients with otherwise normal conditions. Disseminated infections occur rarely and are seen primarily in patients who are receiving immunosuppressive medications or who have neutropenia. Often life-threatening when infection is disseminated and involves the central nervous system, this diagnosis is difficult to make rapidly because S. apiospermum (P. boydii) mimics Aspergillus spp. and Fusarium spp., both clinically and histopathologically. Imidazoles such as miconazole, but not amphotericin B, are considered the therapeutic compounds of choice. Improved diagnostic and treatment options are needed to optimize management of infections with S. apiospermum (P. boydii).


Asunto(s)
Encefalopatías/microbiología , Trasplante de Corazón , Micetoma/diagnóstico , Pseudallescheria/aislamiento & purificación , Adulto , Enfermedades del Sistema Nervioso Central/microbiología , Resultado Fatal , Humanos , Masculino , Micetoma/microbiología , Complicaciones Posoperatorias
18.
J Appl Physiol (1985) ; 58(4): 1143-7, 1985 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-2985531

RESUMEN

We have detected acetone in several brands of heparin. If uncorrected, this leads to errors in measuring acetone in blood collected in heparinized syringes, as in the multiple inert gas elimination technique for measuring ventilation-perfusion ratio (VA/Q) distributions. Error for acetone retention [R = arterial partial pressure-to-mixed venous partial pressure (P-V) ratio] is usually small, because R is normally near 1.0, and the error is similar in arterial and mixed venous samples. However, acetone excretion [E = mixed expired partial pressure (P-E)-to-P-V ratio] will appear erroneously low, because P-E is accurately measured in dry syringes, but P-V is overestimated. A physical model of a homogeneous alveolar lung at room temperature and without dead space shows: the magnitude of acetone E error depends upon the ratio of blood sample to heparinized saline volumes and acetone partial pressures, without correction, acetone E can be less than that of less soluble gases like ether, a situation incompatible with conventional gas exchange theory, and acetone R and E can be correctly calculated using the principle of mass balance if the acetone partial pressure in heparinized saline is known. Published data from multiple inert gas elimination experiments with acetone-free heparin, in our labs and others, are within the limits of experimental error. Thus the hypothesis that acetone E is anomalously low because of physiological mechanisms involving dead space tissue capacitance for acetone remains to be tested.


Asunto(s)
Acetona/farmacología , Heparina/análisis , Pruebas de Función Respiratoria/métodos , Relación Ventilacion-Perfusión , Acetona/análisis , Animales , Recolección de Muestras de Sangre , Perros , Estudios de Evaluación como Asunto , Gases Nobles
19.
J Appl Physiol (1985) ; 74(3): 1287-92, 1993 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-8482669

RESUMEN

Nitric oxide (NO) is an endogenous endothelium-derived relaxing factor that participates in the regulation of vascular tone. We studied the effects of inhaled NO gas on transient hypoxic pulmonary vasoconstriction and normal lungs in mechanically ventilated sheep. We measured hemodynamics and pulmonary gas exchange. For gas exchange measurements we used conventional blood gas analysis and the multiple inert gas elimination technique to estimate ventilation-perfusion heterogeneity. Our hypotheses were 1) inhaled NO reverses hypoxic pulmonary vasoconstriction, 2) the hemodynamic effects of inhaled NO are limited to the pulmonary circulation, and 3) inhaled NO does not impair pulmonary gas exchange and may redistribute blood flow to better ventilated areas of the lungs. Hypoxic pulmonary vasoconstriction was induced by using a hypoxic inspiratory gas mixture. The addition of 20 ppm NO to the hypoxic inspiratory gases returned pulmonary arterial pressure to baseline values. Systemic hemodynamics and gas exchange indexes derived from conventional blood gas analysis remained constant. Gas exchange indexes for ventilation-perfusion ratios and gas dispersions improved. The addition of 20 ppm NO to medical air (21% O2) had no such significant effects on hemodynamics or pulmonary gas exchange. Our findings show that inhaled NO reverses transient hypoxic pulmonary vasoconstriction. The hemodynamic effects of NO are limited to the pulmonary circulation; it does not impair pulmonary gas exchange. Moreover, it redistributes blood flow to better ventilated alveoli. As such, NO has potential in the treatment of lung diseases associated with pulmonary hypertension.


Asunto(s)
Hipoxia/fisiopatología , Óxido Nítrico/farmacología , Circulación Pulmonar/efectos de los fármacos , Intercambio Gaseoso Pulmonar/efectos de los fármacos , Vasoconstricción/efectos de los fármacos , Administración por Inhalación , Animales , Análisis de los Gases de la Sangre , Hemodinámica/efectos de los fármacos , Metahemoglobinemia/inducido químicamente , Metahemoglobinemia/metabolismo , Óxido Nítrico/administración & dosificación , Respiración Artificial , Ovinos , Resistencia Vascular/efectos de los fármacos
20.
Infect Dis Clin North Am ; 15(2): 671-702, xi, 2001 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-11447714

RESUMEN

The immunocompromised host's susceptibility to infections often present a difficult diagnostic challenge to the physician. A working knowledge of the host immune defenses and microbiologic complications that can occur when these functions are compromised provides a more focused framework for further evaluation and management. Infections in these patients are often morbid and life-threatening, creating an urgent need for prompt diagnosis. The skin may manifest the first clue(s) of a serious underlying infection. Appropriate workup and diagnosis of cutaneous lesions provide an expeditious, noninvasive, and potentially life-saving approach to the immunocompromised host with a dermatologic infection.


Asunto(s)
Huésped Inmunocomprometido , Enfermedades de la Piel/microbiología , Humanos , Enfermedades del Sistema Inmune/complicaciones , Neutropenia/microbiología , Infecciones Oportunistas/microbiología , Enfermedades de la Piel/inmunología , Enfermedades de la Piel/patología
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA