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1.
Hernia ; 27(1): 93-104, 2023 02.
Artículo en Inglés | MEDLINE | ID: mdl-36125632

RESUMEN

PURPOSE: International guidelines suggest the use of lapro-endoscopic technique for primary unilateral inguinal hernia (IHR) because of lower postoperative pain and reduction in chronic pain. It is unclear if the primary benefit is due to the minimally invasive approach, the posterior mesh position or both. Further research evaluating posterior mesh placement using open preperitoneal techniques is recommended. A potential benefit of open preperitoneal repair is the avoidance of general anesthesia, as these repairs can be performed under local anesthesia. This study compares clinical and patient-reported outcomes after unilateral laparo-endoscopic, robotic, and open posterior mesh IHRs. METHODS: We performed a propensity score matched analysis of patients undergoing IHR between 2012 and 2021 in the Abdominal Core Health Quality Collaborative registry. 10,409 patients underwent a unilateral IHR via a posterior approach. Hernia repairs were performed via minimally invasive surgery (MIS) which includes laparoscopic and robotic transabdominal preperitoneal (TAPP), laparoscopic totally extraperitoneal (TEP), or open transrectus preperitoneal/open preperitoneal (TREPP/OPP) approaches. Propensity score matching (PSM) utilizing nearest neighbor matching accounted for differences in baseline characteristics and possible confounding variables between groups. We matched 816 patients in the MIS cohort with 816 patients in the TREPP/OPP group. Outcomes included patient reported quality of life, hernia recurrence, and postoperative opioid use. RESULTS: Improvement was seen after TREPP/OPP as compared to MIS IHR in EuraHS at 30 days (Median(IQR) 7.0 (2.0-16.64) vs 10 (2.0-24.0); OR 0.69 [0.55-0.85]; p = 0.001) and 6 months (1.0 (0.0-4.0) vs 2.0 (0.0-4.0); OR 0.63 [0.46-85]; p = 0.002), patient-reported opioid use at 30-day follow-up (18% vs 45% OR 0.26 [0.19-0.35]; p < 0.001), and rates of surgical site occurrences (0.8% vs 4.9% OR 0.16 [0.06-0.35]; p < 0.001). There were no differences in EuraHS scores and recurrences at 1 year. CONCLUSIONS: This study demonstrates a potential benefit of open posterior mesh placement over MIS repair in short-term quality of life and seroma formation with equivalent rates of hernia recurrence. Further study is needed to better understand these differences and determine the reproducibility of these findings outside of high-volume specialty centers.


Asunto(s)
Hernia Inguinal , Laparoscopía , Procedimientos Quirúrgicos Robotizados , Humanos , Hernia Inguinal/cirugía , Hernia Inguinal/etiología , Procedimientos Quirúrgicos Robotizados/efectos adversos , Mallas Quirúrgicas , Puntaje de Propensión , Calidad de Vida , Analgésicos Opioides , Reproducibilidad de los Resultados , Herniorrafia/efectos adversos , Herniorrafia/métodos , Laparoscopía/efectos adversos , Laparoscopía/métodos , Resultado del Tratamiento
2.
J Chem Phys ; 139(10): 104303, 2013 Sep 14.
Artículo en Inglés | MEDLINE | ID: mdl-24050340

RESUMEN

In this manuscript, rotational spectra of four new isotopologues of the S-H···π bonded C2H4···H2S complex, i.e., C2D4···H2S, C2D4···D2S, C2D4···HDS, and (13)CCH4···H2S have been reported and analyzed. All isotopologues except C2D4···HDS show a four line pattern whereas a doubling of the transition frequencies was observed for C2D4···HDS. These results together with our previous report on the title complex [M. Goswami, P. K. Mandal, D. J. Ramdass, and E. Arunan, Chem. Phys. Lett. 393(1-3), 22-27 (2004)] confirm that both subunits (C2H4 and H2S) are involved in large amplitude motions leading to a splitting of each rotational transition to a quartet. Further, the results also confirm that the motions which are responsible for the observed splittings involve both monomers. Molecular symmetry group analysis, considering the interchange of equivalent H atoms in H2S and C2H4 could explain the observed four line pattern and their intensities in the microwave spectrum. In addition, hydride stretching fundamentals of the complex were measured using coherence-converted population transfer Fourier Transform Microwave-infrared (IR-MW double resonance) experiments in the S-H and C-H stretch regions. Changes in the tunneling splittings upon vibrational excitation are consistent with the isotopic dependence of pure rotational transitions. A complexation shift of 2.7-6.5 cm(-1) has been observed in the two fundamental S-H stretching modes of the H2S monomer in the complex. Vibrational pre-dissociation in the bound S-H stretch has been detected whereas the instrument-limited line-shapes in other S-H and C-H stretches indicate slower pre-dissociation rate. Some local perturbations in the vibrational spectra have been observed. Two combination bands have been observed corresponding to both the S-H stretching fundamentals and what appears to be the intermolecular stretching mode at 55 cm(-1). The tunneling splitting involved in the rotation of C2H4 unit has been deduced to be 1.5 GHz from the IR-MW results. In addition, ab initio barrier heights derived for different motions of the monomers support the experimental results and provide further insight into the motions causing the splitting.

3.
Rev Sci Instrum ; 82(5): 056105, 2011 May.
Artículo en Inglés | MEDLINE | ID: mdl-21639553

RESUMEN

The creation of thin, buried, and electrically conducting layers within an otherwise insulating diamond by annealed ion implantation damage is well known. Establishing facile electrical contact to the shallow buried layer has been an unmet challenge. We demonstrate a new method, based on laser micro-machining (laser ablation), to make reliable electrical contact to a buried implant layer in diamond. Comparison is made to focused ion beam milling.

4.
Mol Reprod Dev ; 74(1): 88-96, 2007 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-16941670

RESUMEN

The ability of synthetic arginine-glycine-aspartic acid (RGD)-containing peptides to induce intracellular calcium transients similar to those observed at fertilization by spermatozoa in the bovine has been reported (Campbell et al., 2000: Biol Reprod 62:1702-1709; Sessions et al., 2006. Mol Reprod Dev). These results also indicated the ability of synthetic RGD-containing peptides to induce activation and subsequent parthenogenetic development to the blastocyst stage, although, at numbers lower than observed with control in vitro fertilization (IVF). Evidence has been provided indicating the important effect of surrounding regions on the biological activity of the RGD sequence (Zhu and Evans, 2002; Sessions et al., 2006). The current experiments were designed to use natural RGD-containing sequences (disintegrins) to understand their effects. A total of three RGD-containing snake venom peptides (Kistrin (K), Elegantin (Ele), and Echistatin (Ech)) and one nonRGD-containing venom (Erabutoxin B (EB; control) were used at three concentrations (0.1, 1, and 10 micro g /ml) to induce parthenogenetic development to the blastocyst stage and in conjunction (1.0, 5.0, and 10 micro g/ml) with spermatozoa to evaluate competitive inhibition of fertilization and subsequent development. A (P < 0.01) higher number of bovine oocytes developed to the blastocyst stage after incubation with K, Ele and Ech at 1.0 micro g/ml, and was not different (P > 0.01) from IVF control. Fertilization was significantly reduced (P < 0.01) at all concentrations of K, Ele and Ech as compared to IVF control. No reduction (P > 0.05) was observed in EB (nonRGD) treated oocytes. These results support the involvement of a disintegrin-integrin interaction at fertilization in the bovine resulting in activation and subsequent development.


Asunto(s)
Bovinos/embriología , Fertilización In Vitro/efectos de los fármacos , Oligopéptidos/farmacología , Oocitos/efectos de los fármacos , Partenogénesis/efectos de los fármacos , Venenos de Serpiente/química , Secuencia de Aminoácidos , Animales , Calcio/farmacología , Cationes Bivalentes/farmacología , Femenino , Magnesio/farmacología , Manganeso/farmacología , Datos de Secuencia Molecular , Oligopéptidos/análisis , Oocitos/crecimiento & desarrollo , Péptidos/síntesis química , Péptidos/química , Péptidos/farmacología , Reacción en Cadena de la Polimerasa
5.
Mol Reprod Dev ; 73(5): 651-7, 2006 May.
Artículo en Inglés | MEDLINE | ID: mdl-16493691

RESUMEN

Integrins have been shown to be involved in the process of fertilization and many integrin-ligand interactions are mediated through the recognition of an arginine-glycine-aspartic acid (RGD) sequence. Despite the fact the RGD domain is a principal player in determining the functional characteristics of an adhesive protein, increasing evidence has accumulated implicating the amino acids flanking the RGD sequence in determining the functional properties of the RGD-containing protein. A set of linear peptides in which the amino acid sequence in and around the RGD tri-peptide was modified was synthesized to better understand the specificity of the RGD-receptor interaction. Mature oocytes were fertilized in vitro in the presence of RGD-containing and RGD-modified peptides. Both the RGD-containing and RGD-modified peptides impaired the ability of sperm to fertilize bovine oocytes, illustrated by a reduction in cleavage. The linear modified RGD containing peptides were also examined for their ability to induce parthenogenetic development with the objective of providing a linear RGD peptide with greater biological activity than the one (GRGDSPK) used previously (Campbell et al., 2000). The data demonstrate the specificity of the receptor for the RGD sequence, further implicate the involvement of integrins in the process of bovine fertilization, and illustrate the importance of the amino acids surrounding the RGD sequence in determining the binding and functional properties of RGD-containing peptides. The data support the findings that a linear RGD peptide can block fertilization and that amino acids around the RGD sequence have an impact on the biological activity of the receptor.


Asunto(s)
Sustitución de Aminoácidos , Antineoplásicos/farmacología , Integrinas/agonistas , Oligopéptidos/farmacología , Oocitos/fisiología , Partenogénesis/efectos de los fármacos , Animales , Bovinos , Fase de Segmentación del Huevo/efectos de los fármacos , Fase de Segmentación del Huevo/fisiología , Femenino , Fertilización In Vitro , Integrinas/metabolismo , Masculino , Oligopéptidos/genética , Oocitos/citología , Partenogénesis/fisiología , Interacciones Espermatozoide-Óvulo/efectos de los fármacos
6.
Reproduction ; 131(1): 45-51, 2006 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-16388008

RESUMEN

This study indicated that prolonged exposure of donor cell nuclei to oocyte cytoplasm before activation results in abnormal chromatin morphology, and reduced development to compacted morula/blastocyst stage in vitro. However, after transfer of embryos to recipients, there was no difference in pregnancy rates throughout gestation. Chromatin morphology was evaluated for embryos held 2, 3, 4 and 5 h between fusion and activation. In embryos held 2 h, 15/17 (88.2%) embryos contained condensed chromosomes, while only 12/24 (50.0%) embryos held 3 h exhibited this characteristic. The proportion of embryos with elongated or fragmented chromosomes tended to increase with increased hold time. While 15/19 (78.9%) of embryos held 2 h developed a single pronucleus 6 h after activation, only 8/22 (36.4%) had one pronucleus after a 4-h hold. Embryos held 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0 h cleaved at rates of 207/281 (73.7%), 142/166 (85.5%), 655/912 (71.8%), 212/368 (57.6%), 406/667 (60.9%), 362/644 (56.2%) and 120/228 (52.6%) respectively. Further development to compacted morula/blastocyst stage occurred at rates of 78/281 (27.8%), 42/166 (25.3%), 264/912 (28.9%), 79/368 (21.5%), 99/667 (14.8%), 94/644 (14.6%) and 27/228 (11.8%) respectively. Embryos held less than 2.5 h between fusion and activation established pregnancies in 18/66 (27.3%) of recipients, while embryos held over 2.5 h established pregnancies at a rate of 17/57 (29.8%). This study indicates that holding bovine nuclear transfer embryos less than 2.5 h between fusion and activation results in improved nuclear morphology and increased development to compacted morula/blastocyst stage, and results in pregnancy rates equivalent to embryos held over 2.5 h.


Asunto(s)
Clonación de Organismos/métodos , Citoplasma/metabolismo , Técnicas de Transferencia Nuclear , Oocitos/metabolismo , Animales , Calcio/metabolismo , Bovinos , Núcleo Celular/metabolismo , Núcleo Celular/ultraestructura , Células Cultivadas , Cromatina/ultraestructura , Estimulación Eléctrica , Transferencia de Embrión , Desarrollo Embrionario , Femenino , Técnica del Anticuerpo Fluorescente , Ionomicina/farmacología , Ionóforos/farmacología , Oocitos/ultraestructura , Partenogénesis , Embarazo , Factores de Tiempo
7.
J Healthc Qual ; 23(1): 4-7, 48; quiz 8, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-23413462

RESUMEN

Blame typically follows an adverse event, blame of self and blame of others. However, blame confounds efforts to identify and fix fatal systems flaws. Outlined here are four practical techniques for overcoming blame and identifying systems. Most importantly, blame must be expected and recognized in its many aspects; once recognized, it can be overcome. Other' approaches include isolating decisions about discipline from the systems review process, distinguishing between an adverse clinical outcome and a systems flaw, and asking the right questions atthe beginning of analysis.


Asunto(s)
Errores Médicos , Chivo Expiatorio , Educación Continua , Errores Médicos/prevención & control , Estados Unidos
8.
Annu Rev Phys Chem ; 51: 323-53, 2000.
Artículo en Inglés | MEDLINE | ID: mdl-11031285

RESUMEN

The standard description of the vibrational and rotational motion of polyatomic molecules, as expressed by the distortable rotor/harmonic oscillator approximation, provides an adequate description of the molecular quantum states only in regions of low total state density. When the total state density is large, exceeding 100 states/cm(-1), the vibrational dynamics are "dissipative" and the fundamental process of intramolecular vibrational energy redistribution is operative. The presence of intramolecular vibrational energy redistribution leads to molecular quantum states of a qualitatively different nature. With respect to a normal-mode vibrational basis, these quantum states are "highly mixed" in their vibrational character and represent nuclear motion that is a combination of all the normal-mode motions. This review describes frequency domain spectroscopy techniques designed to probe the vibrational, rotational, and structural composition of these eigenstates. Recent work that investigates spectroscopy between highly mixed states is also reviewed.

9.
Med Microbiol Immunol ; 188(4): 161-8, 2000 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-10917152

RESUMEN

Nocardia asteroides GUH-2 (GUH-2) invades the nigrostriatal region of the brain in mice [15]. Selective dopaminergic neuronal dropout in the substantia nigra results in parkinsonian changes characterized by movement disorders responsive to L-dopa [15]. This is the only reported example of an experimental bacterial model for parkinsonism. Following i.v. inoculation of GUH-2 into the non-human primate Macaca fasicularius, the nocardiae preferentially invaded and grew within the basal ganglia (substantia nigra, caudate, putamen, and globus pallidus) often without inducing apparent inflammation. Reduced, limited growth of nocardiae occurred in the white matter of the cerebral cortex, medulla, and hippocampus, whereas neither significant adherence to nor growth within the meninges was observed. Twenty-four hours after injection, nocardial cells were found within capillary endothelial cells, the basal lamina, neurons, astroglia and in axonal extensions. The bacteria, in endothelial cells, were surrounded by a unit membrane, but in the basal lamina they appeared to be free and not membrane bound. After the organisms passed into the brain parenchyma, the nocardiae once again became surrounded by membrane, often being encapsulated by numerous layers with the innermost layer tightly adherence to the bacterial surface. There was a propensity for nocardial growth within and along myelinated axons, either with or without disruption to the surrounding myelin sheath. There was electron microscopic evidence that the nocardiae induced a neurodegenerative response especially in the substantia nigra region. Thus, the early interactions of GUH-2 within the primate brain appeared to be similar to those reported in the mouse.


Asunto(s)
Ganglios Basales/microbiología , Encéfalo/microbiología , Nocardiosis/microbiología , Nocardia asteroides/patogenicidad , Animales , Encéfalo/inmunología , Encéfalo/patología , Encéfalo/ultraestructura , Modelos Animales de Enfermedad , Femenino , Humanos , Macaca fascicularis , Masculino , Nocardiosis/inmunología , Nocardiosis/patología , Nocardia asteroides/inmunología
10.
Eur J Pharmacol ; 334(1): 31-8, 1997 Sep 03.
Artículo en Inglés | MEDLINE | ID: mdl-9346324

RESUMEN

The consequences of monoamine oxidase and catechol-O-methyltransferase inhibition on the effective turnover of dopamine were investigated using 6-[18F]L-3-4-dihydroxyphenylalanine (6-[18F]L-DOPA) and positron emission tomography. The effective dopamine turnover was expressed as the ratio between the rate of reversibility of 6-[18F]L-DOPA trapping (k[loss]) and the rate of uptake of 6-[81F]L-DOPA (Ki) in the striatum of normal cynomolgus monkeys. The monkeys received 6-[18F]L-DOPA scans, untreated or after pretreatment with either the peripheral catechol-O-methyltransferase inhibitor nitecapone; the peripheral and central catechol-O-methyltransferase inhibitor tolcapone; the monoamine oxidase inhibitors deprenyl or pargyline; a combination of tolcapone and the monoamine oxidase inhibitors. Tolcapone alone or combined with the monoamine oxidase inhibitors produced a significant decrease in the dopamine turnover (55 to 65%). Neither nitecapone nor monoamine oxidase inhibition alone produced significant changes. These results may have implications for the use of central catechol-O-methyltransferase inhibitors added to routine levodopa therapy in parkinsonian patients.


Asunto(s)
Antiparkinsonianos/metabolismo , Benzofenonas/farmacología , Inhibidores de Catecol O-Metiltransferasa , Catecoles/farmacología , Dopamina/metabolismo , Inhibidores Enzimáticos/farmacología , Levodopa/metabolismo , Inhibidores de la Monoaminooxidasa/farmacología , Pentanonas/farmacología , Animales , Radioisótopos de Flúor , Macaca fascicularis/metabolismo , Nitrofenoles , Proyectos Piloto , Tolcapona , Tomografía Computarizada de Emisión/métodos , Corteza Visual/efectos de los fármacos
11.
J Nucl Med ; 38(10): 1568-74, 1997 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-9379194

RESUMEN

UNLABELLED: Graphical methods to analyze tracer time-course data allow reliable quantitation of the rate of incorporation of tracer from plasma into a "trapped" kinetic component, even when the details of the kinetic model are unknown. Applications of the method over long time periods often expose the slow reversibility of the trapping process. In the extended graphical method, both trapping rate and a presumed first-order loss rate constant are estimated simultaneously from the time-course data. METHODS: We applied the extended graphical method to 6-fluoro-L-dopa (6-FD), simultaneously estimating the rate of uptake (Ki) and the rate constant for loss from the trapped component (K(loss)) in a single fitting procedure. We applied this approach to study the effects of two catechol-O-methyl-transferase inhibitors on the kinetics of 6-FD in cynomolgus monkeys. RESULTS: Inhibition of peripheral O-methylation with either inhibitor, confirmed by high-performance liquid chromatography analysis of labeled compounds in arterial plasma, had no significant effect on Ki, in agreement with previously reported studies. In contrast, tolcapone, a catechol-O-methyl-transferase inhibitor, having central effects in addition to peripheral effects at the dosage used, decreased K(loss) by 40% from control values (p < 0.002), whereas nitecapone, which has no known central activity, had no significant effect. CONCLUSION: This method provides insight into the neurochemical basis for the kinetic behavior of 6-FD in both health and disease and may be used to define the action of centrally active drugs that influence the metabolism of dopamine.


Asunto(s)
Inhibidores de Catecol O-Metiltransferasa , Dihidroxifenilalanina/análogos & derivados , Radioisótopos de Flúor , Tomografía Computarizada de Emisión , Animales , Benzofenonas/farmacología , Encéfalo/diagnóstico por imagen , Encéfalo/metabolismo , Catecol O-Metiltransferasa/fisiología , Catecoles/farmacología , Cromatografía Líquida de Alta Presión , Dihidroxifenilalanina/farmacocinética , Inhibidores Enzimáticos/farmacología , Macaca fascicularis , Masculino , Nitrofenoles , Pentanonas/farmacología , Tolcapona
12.
Behav Neurosci ; 110(6): 1205-28, 1996 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-8986326

RESUMEN

Children and adults were tested on 3 place learning tasks. Children under the age of 7 were inferior to older subjects in solving the tasks by using spatial relational solutions, but subjects of all ages were equally proficient in solving the task by using simple stimulus-reward associations (cued solutions). Accurate performance on the cued versions suggests that neither the general response demands nor the large size of testing environments rendered the tasks differentially inappropriate for young children. Instead, the nature of the cognitive demands were responsible for different levels of performance across the age groups. Because, in animal studies, spatial relational solutions but not cued solutions of these tests require mature and undamaged medial temporal lobe structures, the results suggest that these systems are not fully developed in humans before approximately 7 years of age.


Asunto(s)
Desarrollo Infantil/fisiología , Cognición/fisiología , Orientación/fisiología , Lóbulo Temporal/fisiología , Adolescente , Adulto , Factores de Edad , Niño , Señales (Psicología) , Conducta Exploratoria/fisiología , Femenino , Humanos , Masculino , Aprendizaje por Laberinto/fisiología , Memoria/fisiología , Solución de Problemas/fisiología , Percepción Espacial/fisiología , Análisis y Desempeño de Tareas , Lóbulo Temporal/crecimiento & desarrollo
13.
Neurology ; 45(6): 1199-204, 1995 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-7783889

RESUMEN

Using MRI and PET, we investigated the consequences of manganese intoxication in a primate model of parkinsonism and dystonia. Three rhesus monkeys were injected intravenously with doses of 10 to 14 mg/kg of MnCl2 on seven occasions, each a week apart. Two animals became hypoactive with abnormal extended posturing in the hind limbs. These motor disturbances did not improve with administration of levodopa. In all three monkeys, T1-weighted MRI demonstrated high signal intensities in the regions of the striatum, globus pallidus, and substantia nigra. No significant changes were found on [18F]6-fluoro-L-dopa, [11C]raclopride, or [18F]fluorodeoxyglucose PET. These results are consistent with the pathologic findings, which were primarily confined to the globus pallidus, and indicate that manganese intoxication is associated with preservation of the nigrostriatal dopaminergic pathway, despite clinical evidence of parkinsonian deficits. Chronic manganese intoxication may cause parkinsonism by damaging output pathways downstream to the nigrostriatal dopaminergic pathway. This is consistent with the demonstrated lack of therapeutic response to levodopa.


Asunto(s)
Intoxicación por Manganeso , Enfermedad de Parkinson Secundaria/diagnóstico por imagen , Enfermedad de Parkinson Secundaria/patología , Animales , Carbidopa/administración & dosificación , Cuerpo Estriado/diagnóstico por imagen , Cuerpo Estriado/metabolismo , Cuerpo Estriado/patología , Desoxiglucosa/análogos & derivados , Quimioterapia Combinada , Distonía/tratamiento farmacológico , Distonía/fisiopatología , Fluorodesoxiglucosa F18 , Globo Pálido/diagnóstico por imagen , Globo Pálido/metabolismo , Globo Pálido/patología , Glucosa/metabolismo , Levodopa/administración & dosificación , Macaca mulatta , Imagen por Resonancia Magnética , Masculino , Enfermedad de Parkinson Secundaria/inducido químicamente , Enfermedad de Parkinson Secundaria/tratamiento farmacológico , Racloprida , Salicilamidas , Sustancia Negra/diagnóstico por imagen , Sustancia Negra/metabolismo , Sustancia Negra/patología , Tomografía Computarizada de Emisión
14.
J Air Waste Manag Assoc ; 45(1): 3-11, 1995 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-15658161

RESUMEN

Title III of the 1990 Clean Air Act Amendments designated methanol as a pollutant to be regulated. The U.S. Environmental Protection Agency (EPA), through a contract with Research Triangle Institute, has developed a method for measuring methanol emissions from stationary sources. The methanol sampling train (MST) consists of a glass-lined heated probe, two condensate knockout traps, and three sorbent cartridges packed with Anasorb 747. Samples are desorbed with a 1:1 mixture of carbon disulfide (CS2) and N,N-dimethylformamide (DMF). Condensate water and CS2/ DMF samples are analyzed by gas chromatography with flame ionization detection. The MST has a practical quantitation limit of approximately 3 ppm for a 20-L sample. Samples were shown to be stable for at least two weeks after collection. Field tests of the MST and the National Council of the Paper Industry for Air and Stream Improvement (NCASI) methanol sampling method were conducted at two pulp and paper mills. Sampling and analysis procedures followed EPA Method 301 requirements. The sampling location for the first field test was the inlet vent to a softwood bleach plant scrubber, where the methanol concentration was approximately 30 ppm. The mean recovery of spike was 108.3% for the MST method and 81.6% for the NCASI method. Although neither method showed significant bias at the 95% confidence level, the between-methods bias was significantly different. A second field test was conducted at a vent from a black liquor oxidation tank where the methanol concentration was approximately 350 ppm. Mean spike recoveries were 96.6 and 94.2% for the MST and NCASI methods, respectively. The biases of the two methods and the between-methods bias were not significantly different for the second field test.


Asunto(s)
Contaminantes Atmosféricos/análisis , Monitoreo del Ambiente/métodos , Metanol/análisis , Cromatografía de Gases , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
15.
Life Sci ; 56(21): 1759-66, 1995.
Artículo en Inglés | MEDLINE | ID: mdl-7739350

RESUMEN

In 6-[18F]fluoro-L-dopa (Fdopa)/positron emission tomography (PET) studies, carbidopa pretreatment increases the Fdopa bioavailability to the brain and enhances the intensity of striatal PET images. Different PET research teams have used various carbidopa doses and routes of administration in non-human primate studies. The purpose of this study was to examine the plasma profiles of carbidopa and the effect of the route of administration of carbidopa on a Fdopa/PET scan. Cynomolgus monkeys were given carbidopa either orally (5 mg/kg), intraperitoneally (2.5 and 5 mg/kg) or intravenously (5 mg/kg) 60-90 min prior to the Fdopa injection. Carbidopa-treated monkeys were compared to monkeys without carbidopa treatment. No carbidopa was detected in the plasma samples when it was given orally, possibly due to poor absorption in the gastrointestinal tract. In addition, the striatal and cortical activities were not statistically different from those of the untreated monkeys, indicating that little or no inhibition of the peripheral decarboxylation of Fdopa by carbidopa had taken place. When carbidopa was given intraperitoneally at a dose of 2.5 and 5 mg/kg and intravenously at 5 mg/kg, plasma carbidopa concentrations at the time of Fdopa injection were 0.95 +/- 0.26, 2.22 +/- 0.23 and 2.79 +/- 0.26 micrograms/ml, respectively. Because of inhibition of peripheral decarboxylation of Fdopa by carbidopa, more Fdopa was available for transport into the brain and as a result, both the striatal and cortical activities were significantly higher than those of the untreated monkeys. Carbidopa administration had no effect on either the striatal-to-cortical activity ratio or the striatum uptake value.


Asunto(s)
Carbidopa/administración & dosificación , Carbidopa/sangre , Corteza Cerebral/fisiología , Cuerpo Estriado/fisiología , Administración Oral , Animales , Carbidopa/farmacocinética , Corteza Cerebral/efectos de los fármacos , Cuerpo Estriado/efectos de los fármacos , Dihidroxifenilalanina/análogos & derivados , Inyecciones Intraperitoneales , Inyecciones Intravenosas , Intubación Gastrointestinal , Macaca fascicularis , Premedicación , Factores de Tiempo , Tomografía Computarizada de Emisión
16.
Ann Neurol ; 36(4): 667-70, 1994 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-7944302

RESUMEN

Despite postmortem evidence for an age-related decline in nigrostriatal dopaminergic function, position emission tomography (PET) studies have produced inconsistent results. This may be due to differences in methods or of subject selection. To investigate further the effect of age on dopaminergic function, we performed PET with 6-L-[18F]fluorodopa (FD) on 12 pairs of grandchildren and their grandparents. The FD uptake rate constant (Ki) was calculated using a graphical method for the whole striatum to avoid confounding of the results by striatal atrophy. The mean Ki was significantly lower in grandparents (p = 0.020). These PET observations represent in vivo confirmation of postmortem evidence that nigrostriatal dopaminergic function declines with aging.


Asunto(s)
Envejecimiento/metabolismo , Cuerpo Estriado/metabolismo , Dopamina/metabolismo , Sustancia Negra/metabolismo , Tomografía Computarizada de Emisión , Adulto , Anciano , Cuerpo Estriado/diagnóstico por imagen , Dihidroxifenilalanina/análogos & derivados , Dihidroxifenilalanina/metabolismo , Familia , Femenino , Humanos , Masculino , Sustancia Negra/diagnóstico por imagen
18.
Ann Neurol ; 34(4): 603-8, 1993 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-8215248

RESUMEN

The transport of L-6-fluorodopa and its major metabolites from the blood to the brain, cerebrospinal fluid (CSF), and muscle was studied in carbidopa-pretreated cynomolgus monkeys. A bolus intravenous injection of 18F-L-6-fluorodopa was followed by serial positron emission tomography scans and sampling of cisternal CSF and arterial blood. The relative concentrations of L-6-fluorodopa and its metabolites were determined in blood plasma and CSF by high-performance liquid chromatography. Raising the blood concentration of phenylalanine by intraperitoneal injection markedly reduced the accumulation of tracer in the brain. This indicates that L-6-fluorodopa and 3-O-methylfluorodopa, like native L-dopa and its O-methylated derivative, are transported at the brain capillary by the large neutral amino acid carrier-mediated system, which is subject to saturation and competition by other large neutral amino acids (such as phenylalanine) at physiological plasma concentrations. In contrast, administration of phenylalanine had no effect on the accumulation of tracer either in muscle, or as L-6-fluorodopa and 3-O-methylfluorodopa, in CSF. This suggests that the transport of L-dopa and its derivatives at the blood-CSF barrier differs from the transport at the blood-brain barrier and also that measurement of CSF L-dopa is not a good index of the transport and pharmacokinetics of L-dopa in the brain. However, the effect of phenylalanine administration in reducing the concentration of fluorohomovanillic acid in the CSF suggests that the concentration of homovanillic acid in the CSF is an accurate reflection of dopamine turnover in the brain.


Asunto(s)
Química Encefálica , Encéfalo/metabolismo , Dihidroxifenilalanina/análogos & derivados , Aminoácidos/metabolismo , Animales , Transporte Biológico , Barrera Hematoencefálica , Encéfalo/diagnóstico por imagen , Dihidroxifenilalanina/análisis , Dihidroxifenilalanina/sangre , Dihidroxifenilalanina/líquido cefalorraquídeo , Dihidroxifenilalanina/metabolismo , Radioisótopos de Flúor , Ácido Homovanílico/líquido cefalorraquídeo , Ácido Homovanílico/metabolismo , Macaca fascicularis , Masculino , Fenilalanina/metabolismo , Fenilalanina/farmacología , Tomografía Computarizada de Emisión
19.
Ann Neurol ; 34(3): 331-8, 1993 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-8363350

RESUMEN

Striatal 18F-6-fluorodopa (FD) uptake constants were measured by positron emission tomography in (1) normal cynomolgus monkeys and (2) a series of cynomolgus and rhesus monkeys that had received intracarotid infusions of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). After the animals were killed, the number and average size of dopaminergic neurons in the substantia nigra pars compacta were measured. Striatal levels of dopamine and its metabolites, and the striatal activities of the dopaminergic synthetic enzymes, were also determined. The striatal FD uptake constants showed highly significant positive correlations with both number and size of dopaminergic neurons, indicating atrophy of surviving neurons in MPTP-treated animals. The uptake constants also showed significant positive correlations with striatal levels of dopamine, total catecholamines, and the activities of the synthetic enzymes. Both histochemical and biochemical data on tyrosine hydroxylase suggested some contralateral enzyme loss in these MPTP-treated monkeys, as well as decreased enzyme activity in surviving neurons on the lesioned side. However, residual enzyme activities were apparently not rate limiting to striatal FD uptake. It is concluded that PET-FD measurements by positron emission tomography provide a good index of the integrity of the nigrostriatal pathway.


Asunto(s)
Dihidroxifenilalanina/análogos & derivados , Dopamina/metabolismo , Intoxicación por MPTP , Neuronas/metabolismo , Sustancia Negra/metabolismo , Animales , Transporte Biológico , Dihidroxifenilalanina/metabolismo , Radioisótopos de Flúor , Macaca fascicularis , Masculino , Neuronas/diagnóstico por imagen , Neuronas/efectos de los fármacos , Sustancia Negra/diagnóstico por imagen , Sustancia Negra/efectos de los fármacos , Tomografía Computarizada de Emisión/métodos
20.
J Nucl Med ; 34(3): 481-7, 1993 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-8441044

RESUMEN

The human striatum is small enough for partial volume effects to be important when imaged in positron tomographs with slice widths 10 mm or greater. The combination of interslice distance and slice width in such tomographs results in an axial undersampling of the striatal activity which introduces the additional problem of variation of axial recovery as a function of position of the striatum along the tomograph axis. Using striatal phantoms, we have developed a method that corrects the recovered striatal signal to a maximum value equivalent to that measured when the object is centered with respect to a slice. This makes the recovery independent of the axial position of the striatum. The method also provides an estimate of the total striatal activity by integrating the axial image intensity distribution along the tomograph axis. The method is able to detect and correct for relative axial tilt of the left and right striatum. We applied it to 26 human [18F]-6-L-fluorodopa scans and obtained an average uptake rate constant k value of 0.25 +/- 0.05 ml/min/striatum and a left to right k value percentage asymmetry of 0.1% +/- 6.3%.


Asunto(s)
Cuerpo Estriado/diagnóstico por imagen , Tomografía Computarizada de Emisión , Adulto , Anciano , Humanos , Persona de Mediana Edad , Modelos Estructurales , Tomografía Computarizada de Emisión/métodos
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