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1.
J Am Acad Dermatol ; 87(3): 559-566, 2022 09.
Artículo en Inglés | MEDLINE | ID: mdl-35487332

RESUMEN

BACKGROUND: The incidence of systemic lupus in children with discoid lupus is unknown. OBJECTIVE: This study assessed the baseline characteristics of patients with pediatric discoid lupus erythematosus (pDLE). METHODS: Medical records at 17 sites were reviewed for pediatric dermatology and rheumatology patients with discoid lupus erythematosus. The inclusion criteria were clinical and/or histopathologic diagnosis of discoid lupus erythematosus with an age at onset of <18 years. Baseline data were collected at the first documented visit. Outcomes included diagnosis of systemic lupus erythematosus (SLE) at the baseline visit using the 1997 American College of Rheumatology (primary) and the 2012 Systemic Lupus International Collaborating Clinics (secondary) criteria. RESULTS: Of the >1500 charts reviewed, 438 patients met the inclusion criteria. The cohort was predominantly female (72%) and racially/ethnically diverse. A diagnosis of SLE at the baseline visit (pDLE + SLE) was rendered in 162 (37%) patients using the American College of Rheumatology and in 181 (41%) patients using the Systemic Lupus International Collaborating Clinics criteria. Patients with pDLE + SLE were older at the time of rash onset (median, 12.9 vs 8.9 years; P < .001), with shorter time from discoid lupus erythematosus onset to diagnosis, compared with patients with pDLE-only (median, 2 vs 7 months; P < .001). Patients with pDLE + SLE were more likely to be female (P = .004), with generalized discoid lupus erythematosus and clinically aggressive disease, including end-organ involvement, positive serologies, and higher- titer levels of antinuclear antibodies (P < .001). LIMITATIONS: Retrospective study. CONCLUSION: A diagnosis of discoid lupus erythematosus in adolescence should prompt thorough screening for SLE.


Asunto(s)
Lupus Eritematoso Discoide , Lupus Eritematoso Sistémico , Adolescente , Niño , Estudios de Cohortes , Estudios Transversales , Femenino , Humanos , Lupus Eritematoso Discoide/diagnóstico , Lupus Eritematoso Discoide/epidemiología , Lupus Eritematoso Sistémico/epidemiología , Masculino , Estudios Retrospectivos
2.
Lupus ; 28(14): 1716-1721, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31674268

RESUMEN

Rowell syndrome (RS) is a rare disease characterized by the association of systemic lupus erythematosus (SLE) or cutaneous lupus with lesions similar to erythema multiforme and the presence of autoantibodies including ANA, SSA, SSB, or rheumatoid factor. Due to the low incidence of this disease, the epidemiology of RS is not clear. So far there are 95 cases reported in the literature; of these, only seven cases are pediatric patients. Macrophage activation syndrome (MAS) is an increasingly recognized complication of SLE, although its true prevalence in childhood is still unknown. We describe a unique pediatric patient with RS who developed MAS.


Asunto(s)
Eritema Multiforme/diagnóstico , Lupus Eritematoso Sistémico/diagnóstico , Síndrome de Activación Macrofágica/etiología , Piel/patología , Niño , Diagnóstico Diferencial , Eritema Multiforme/patología , Humanos , Lupus Eritematoso Sistémico/patología , Masculino
3.
J Eur Acad Dermatol Venereol ; 33(12): 2334-2339, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31465591

RESUMEN

BACKGROUND: Autoinflammation and phospholipase Cγ2-associated antibody deficiency and immune dysregulation (APLAID) is an exceedingly rare monogenic autoinflammatory disease. To date, only five cases have been reported with four distinct pathogenic mutations. OBJECTIVES: We present a novel case of APLAID, corroborated by molecular analysis, with newly described clinical findings including central nervous system vasculitis (CNSV); and distinctive histopathological characteristics that may expand our knowledge of this rare disease's phenotype. METHODS: This is a case report presentation of a 3-year-old boy, seen at a reference paediatric hospital in Mexico. His parents authorized the use of his clinical information and photographs. RESULTS: A 3-day-old boy presented to the emergency department with a vesiculo-pustular rash that resolved within 1 week. Two months later, he developed widespread papules and pseudovesicles that evolved into infiltrated plaques. He also had periodical flares of conjunctivitis, diarrhoea and erythematous blistering acral plaques triggered by upper respiratory infections. By the age of 10 months, he experienced seizures and CNSV. Laboratory work-up showed mild neutropenia, decreased serum levels of immunoglobulins and B-cell lymphopenia. A skin biopsy revealed a dense, perivascular and interstitial histiocytic and granulomatous infiltrate, with palisading granulomas, and leucocytoclastic vasculitis with karyorrhexis. APLAID syndrome was confirmed by Sanger sequencing of PLCG2 gene [heterozygous genotype LRG_376t1:c.2543T>C or p.(Leu848Pro)]. CONCLUSIONS: Presence of CNSV has not been previously described in APLAID, however as the number of reported patients with APLAID is very small, it is possible that the overall spectrum of clinical manifestations has not been completely elucidated. The herein identified p.(Leu848Pro) variant was also documented in a Portuguese patient, suggesting that it could be a PLCG2 gene 'hot-spot'.


Asunto(s)
Inflamación/inmunología , Fosfolipasa C gamma/inmunología , Preescolar , Humanos , Masculino , Mutación , Síndrome
4.
Phys Chem Chem Phys ; 21(5): 2325-2336, 2019 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-30656304

RESUMEN

The production of gas-phase hydroperoxyl radicals, HO2, is observed directly from sub-micron airborne TiO2 nanoparticles irradiated by 300-400 nm radiation. The rate of HO2 production as a function of O2 pressure follows Langmuir isotherm behaviour suggesting O2 is involved in the production of HO2 following its adsorption onto the surface of the TiO2 aerosol. Reduction of adsorbed O2 by photogenerated electrons is likely to be the initial step followed by reaction with a proton produced via oxidation of adsorbed water with a photogenerated hole. The rate of HO2 production decreased significantly over the range of relative humidities between 8.7 and 36.9%, suggesting competitive adsorption of water vapour inhibits HO2 production. From the data, the adsorption equilibrium constants were calculated to be: KO2 = 0.27 ± 0.02 Pa-1 and KH2O = 2.16 ± 0.12 Pa-1 for RH = 8.7%, decreasing to KO2 = 0.18 ± 0.01 Pa-1 and KH2O = 1.33 ± 0.04 Pa-1 at RH = 22.1%. The increased coverage of H2O onto the TiO2 aerosol surface may inhibit HO2 production by decreasing the effective surface area of the TiO2 particle and lowering the binding energy of O2 on the aerosol surface, hence shortening its desorption lifetime. The maximum yield (i.e. when [O2] is projected to atmospherically relevant levels) for production of gas-phase HO2, normalised for surface area and light intensity, was found to be at a RH of 8.7% for the 80% anatase and 20% rutile formulation of TiO2 used here. This yield decreased to as the RH was increased to 22.1%. Using this value, the rate of production of HO2 from TiO2 surfaces under atmospheric conditions was estimated to be in the range 5 × 104-1 × 106 molecule cm-3 s-1 using observed surface areas of mineral dust at Cape Verde, and assuming a TiO2 fraction of 4.5%. For the largest loadings of dust in the troposphere, the rate of this novel heterogeneous production mechanism begins to approach that of HO2 production from the gas-phase reaction of OH with CO in unpolluted regions. The production of gas-phase OH radicals could only be observed conclusively at high aerosol surface areas, and was attributed to the decomposition of H2O2 at the surface by photogenerated electrons.

5.
Clin Exp Dermatol ; 43(3): 303-305, 2018 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-29280519

RESUMEN

Morphoea, also known as localized scleroderma, is a disorder characterized by excessive collagen deposition leading to thickening of the dermis and/or subcutaneous tissues. Intravenous IgG therapy has induced improvement in some fibrotic conditions. The primary indication for subcutaneous IgG (SCIG) is in primary immunodeficiency disorders as replacement therapy; however, recently there has been considerable interest in SCIG as an immunomodulatory agent. We report an 11-year-old girl with deep morphoea who was successfully treated with SCIG.


Asunto(s)
Inmunoglobulina G/administración & dosificación , Esclerodermia Localizada/tratamiento farmacológico , Niño , Femenino , Humanos , Inmunoglobulina G/efectos adversos , Infusiones Subcutáneas , Inyecciones Subcutáneas , Esclerodermia Localizada/patología
7.
Environ Sci Technol ; 49(8): 4878-85, 2015 Apr 21.
Artículo en Inglés | MEDLINE | ID: mdl-25811311

RESUMEN

Measurements of HO2 uptake coefficients (γ) were made onto a variety of organic aerosols derived from glutaric acid, glyoxal, malonic acid, stearic acid, oleic acid, squalene, monoethanol amine sulfate, monomethyl amine sulfate, and two sources of humic acid, for an initial HO2 concentration of 1 × 10(9) molecules cm(-3), room temperature and at atmospheric pressure. Values in the range of γ < 0.004 to γ = 0.008 ± 0.004 were measured for all of the aerosols apart from the aerosols from the two sources of humic acid. For humic acid aerosols, uptake coefficients in the range of γ = 0.007 ± 0.002 to γ = 0.09 ± 0.03 were measured. Elevated concentrations of copper (16 ± 1 and 380 ± 20 ppb) and iron (600 ± 30 and 51 000 ± 3000 ppb) ions were measured in the humic acid atomizer solutions compared to the other organics that can explain the higher uptake values measured. A strong dependence upon relative humidity was also observed for uptake onto humic acid, with larger uptake coefficients seen at higher humidities. Possible hypotheses for the humidity dependence include the changing liquid water content of the aerosol, a change in the mass accommodation coefficient or in the Henry's law constant.


Asunto(s)
Aerosoles/química , Peróxidos/química , Contaminantes Atmosféricos/química , Presión Atmosférica , Cobre/análisis , Cobre/química , Sustancias Húmicas , Humedad , Hierro/análisis , Hierro/química , Temperatura
8.
Clín. investig. ginecol. obstet. (Ed. impr.) ; 40(5): 223-226, sept.-oct. 2013. ilus
Artículo en Español | IBECS | ID: ibc-115867

RESUMEN

La incidencia de hemorragia subaracnoidea (HSA) parece aumentar durante el embarazo y origina un amplio grupo de problemas a resolver tales como la realización de pruebas de imagen con protección radiológica, la viabilidad del feto, la finalización del parto, el manejo neuroanestésico, los fármacos a utilizar y la decisión de intervención neuroquirúrgica. El diagnóstico y el tratamiento precoz de la HSA es fundamental para obtener buenos resultados tanto para la madre como para el feto y evitar complicaciones. Se exponen 3 casos de hemorragia intracraneal de aparición espontánea durante el embarazo que se registraron en el Hospital Virgen de las Nieves de Granada durante los años 2008-2010 (AU)


The incidence of subarachnoid hemorrhage increases during pregnancy and involvesa wide range of activities and issues such as the performance of imaging tests with radiological protection, assessment of fetal viability, termination of pregnancy, the patient’s anesthetic management, the drugs to be used, and neurosurgical intervention. Early diagnosis and treatment of this event are essential to obtain favorable outcomes for the mother and fetus and to avoid complications. We describe three cases of intracranial hemorrhage with spontaneous onset during pregnancy registered at the Virgen de las Nieves’ Hospital between 2008 and 2010 and provide a review of the topic (AU)


Asunto(s)
Humanos , Femenino , Embarazo , Hemorragia Subaracnoidea/complicaciones , Complicaciones del Embarazo , Traumatismos por Radiación/prevención & control , Viabilidad Fetal , Resultado del Embarazo , Diagnóstico Precoz
9.
Phys Chem Chem Phys ; 15(37): 15612-22, 2013 Oct 07.
Artículo en Inglés | MEDLINE | ID: mdl-23942624

RESUMEN

The formation of atmospherically relevant iodine oxides IxOy (x = 1,…,3, y = 1,…,7) has been studied experimentally using time-of-flight mass spectrometry combined with a soft ionisation source, complemented with ab initio electronic structure calculations of ionisation potentials and bond energies at a high level of theory presented in detail in the accompanying paper (Galvez et al., 2013). For the first time, direct experimental evidence of the I2Oy (y = 1,…,5) molecules in the gas phase has been obtained. These chemical species are observed alongside their precursors (IO and OIO) in experiments where large amounts of aerosol are also generated. The measured relative concentrations of the IxOy molecules and their dependence on ozone concentration have been investigated by using chemical modelling and rate theory calculations. It is concluded that I2O4 is the most plausible candidate to initiate nucleation, while the contribution of I2O5 in the initial steps is likely to be marginal. The absence of large I3Oy (y = 3,…,6) peaks in the mass spectra and the high stability of the I2O4-I2O4 dimer indicate that dimerisation of I2O4 is the key step in iodine oxide particle nucleation.

10.
Phys Chem Chem Phys ; 15(31): 12829-45, 2013 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-23806979

RESUMEN

Laboratory studies were conducted to investigate the kinetics of HO2 radical uptake onto submicron inorganic salt aerosols. HO2 reactive uptake coefficients were measured at room temperature using an aerosol flow tube and the Fluorescence Assay by Gas Expansion (FAGE) technique that allowed for measurements to be conducted under atmospherically relevant HO2 concentrations ([HO2] = 10(8) to 10(9) molecule cm(-3)). The uptake coefficient for HO2 uptake onto dry inorganic salt aerosols was consistently below the detection limit (γ(HO2) < 0.004). The mass accommodation coefficient of HO2 radicals onto Cu(II)-doped (NH4)2SO4 aerosols was measured to be α(HO2) = 0.4 ± 0.3 representing the kinetic upper limit to γ. For aqueous (NH4)2SO4, NaCl and NH4NO3 aerosols not containing traces of transition metal ions, a range of γ(HO2) = 0.003-0.02 was measured. These values were much lower than γ values previously measured on aqueous (NH4)2SO4 and NaCl aerosols and also those typically used in atmospheric models (γ(HO2) = 0.1-1.0). Evidence is presented showing that the HO2 uptake coefficients onto aqueous salt aerosol particles are dependent both on the exposure time to the aerosol and on the HO2 concentration used.


Asunto(s)
Sulfato de Amonio/química , Radical Hidroxilo/química , Nitratos/química , Peróxidos/química , Cloruro de Sodio/química , Aerosoles/química , Sales (Química)/química
11.
Actas Dermosifiliogr ; 103(1): 59-62, 2012 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-22456594

RESUMEN

Onychomycosis is known to have predisposing factors and a high prevalence within families that cannot be explained by within-family transmission. We determined the frequency of HLA-B and HLA-DR haplotypes in 25 families of Mexican patients with onychomycosis in order to define the role of the class II major histocompatibility complex (MHC) in genetic susceptibility to this infection. Seventy-eight subjects participated in the study, 47 with onychomycosis and 31 healthy individuals. The frequencies of the HLA-B and HLA-DR haplotypes were compared with those found in first-degree relatives without onychomycosis and in a historic control group of healthy individuals. The frequencies in the controls were similar to those of the healthy relatives of the patients. However, on comparison of the patients with historic controls, we detected a higher frequency of the HLA-DR8 haplotype (P=.03; odds ratio, 1.89; 95% confidence interval, 0.98-36). These findings suggest that there are polymorphisms in genes of the MHC that increase susceptibility to onychomycosis, particularly haplotype HLA-DR8.


Asunto(s)
Dermatosis del Pie/genética , Genes MHC Clase II , Genes MHC Clase I , Antígenos HLA-B/genética , Antígenos HLA-DR/genética , Dermatosis de la Mano/genética , Onicomicosis/genética , Polimorfismo Genético , Tiña del Cuero Cabelludo/genética , Alelos , Etnicidad/genética , Salud de la Familia , Dermatosis del Pie/epidemiología , Dermatosis del Pie/etnología , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Subtipos Serológicos HLA-DR/genética , Dermatosis de la Mano/epidemiología , Dermatosis de la Mano/etnología , Haplotipos , Humanos , México/epidemiología , Onicomicosis/epidemiología , Onicomicosis/etnología , Tiña del Cuero Cabelludo/epidemiología
12.
Med Phys ; 39(6Part16): 3794, 2012 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-28517226

RESUMEN

PURPOSE: The delivery of the therapeutic radiation dose to the tumour in photon radiotherapy, also implies dose deposition in distant organs (peripheral dose) related to secondary cancers induction (Hall and Wuu, Int J Radiat Oncol Biol Phys 56:83-88, 2003). Therefore, peripheral dose estimation in MU-demanding techniques, such as Helical TomoTherapy (HT), becomes relevant. TLD measurements and Monte Carlo modelling were compared by D'Agostino (Strahlenther Onkol 187:693, 2011). The purpose of this work was to find out experimental models predicting the equivalent photon dose as a function of the distance to the isocenter for different treatment types. The prostate case is presented here. METHODS: A HT prostate plan was delivered to an anthropomorphic phantom mimicking a male adult. The phantom was made of polyethylene blocks whereas light wood was used for lungs. 16 points distributed along the phantom, covering different depths, were selected (Sánchez-Doblado IFMBE, World Congress Med Phys & Biomed Eng, 259-261, 2009). Additionally, a polyethylene sheet was inserted in the phantom to measure the off-axis dose profile at midplane depth. Measurements were carried out with standard TLD-100 pairs of dosimeters (calibrated in a 137Cs source). RESULTS: Two-exponential-terms curve fitting was carried out to model separately the scatter and leakage contribution (f=a*exp(-b*x)+c*exp(-d*x)). The former resulted predominant in the proximal region (10=x=14cm) and the latter in the distal re gion (x=14cm). Both components equate at 18cm. Scatter contribution becomes negligible for x=23cm. Points at 5cm were not used for the model as they are too close to the isocenter to be considered as peripheral dose. Model fits well experimental data (13% mean deviation). Only depths behind the build-up region could be properly modelled. CONCLUSIONS: Peripheral photon dose profiles in HT treatments have been modelled by a two-exponential-terms curve modelling separately scatter and leakage.

13.
Actas Dermosifiliogr ; 103(1): 59-62, 2012.
Artículo en Español | MEDLINE | ID: mdl-21742300

RESUMEN

Onychomycosis is known to have predisposing factors and a high prevalence within families that cannot be explained by within-family transmission. We determined the frequency of HLA-B and HLA-DR haplotypes in 25 families of Mexican patients with onychomycosis in order to define the role of the class II major histocompatibility complex (MHC) in genetic susceptibility to this infection. Seventy-eight subjects participated in the study, 47 with onychomycosis and 31 healthy individuals. The frequencies of the HLA-B and HLA-DR haplotypes were compared with those found in first-degree relatives without onychomycosis and in a historic control group of healthy individuals. The frequencies in the controls were similar to those of the healthy relatives of the patients. However, on comparison of the patients with historic controls, we detected a higher frequency of the HLA-DR8 haplotype (P=.03; odds ratio, 1.89; 95% confidence interval, 0.98-36). These findings suggest that there are polymorphisms in genes of the MHC that increase susceptibility to onychomycosis, particularly haplotype HLA-DR8.


Asunto(s)
Antígenos HLA-B/genética , Subtipos Serológicos HLA-DR/genética , Onicomicosis/genética , Polimorfismo Genético , Estudios de Casos y Controles , Humanos
14.
Case Rep Infect Dis ; 2011: 181782, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-22567461

RESUMEN

Zygomycosis are invasive mould infections, rarely diagnosed in hematologic patients. Most of the cases published are in patients with prolonged neutropenia, along with other risk factors such as the use of prior broad-spectrum antibiotics (including new antifungal agents, such as voriconazole), diabetes mellitus (with or without ketoacidosis), malnutrition, iron overload (with or without the use of deferoxamine). These infections have poor prognosis due to the involvement of vital anatomic structures and late diagnosis. Until recent years, the treatment was based on high doses of amphotericin B plus surgical debridement. Here we present two patients with hematologic diseases (one with leukemia, the second with aplastic anemia) with an impaired immune system and the diagnosis of zygomycosis. The survival of one of them was mainly due to early diagnosis and surgical debridement; unfortunately the second was misdiagnosed as an extensive ecchymosis due to thrombocytopenia and died with CNS involvement.

15.
Clín. investig. ginecol. obstet. (Ed. impr.) ; 35(5): 166-171, sept. 2008. tab
Artículo en Es | IBECS | ID: ibc-67926

RESUMEN

Objetivo: Valorar la influencia de la analgesia vía epidural en la saturación de oxígeno fetal (SpO2) intraparto y los patrones de frecuencia cardíaca fetal. Material y métodos: Se realizó un estudio prospectivo con 50 gestantes a las que, durante el período de dilatación, se les administró analgesia por vía epidural, y que fueron monitorizadas mediante cardiotocografía y pulsioximetría fetal a través de una sonda Nellcor FS-14®. Resultados: El valor de SpO2 preepidural fue del 48,5 ± 7,8%. Durante los primeros 15 min postepidural se obtuvo la cifra de 47,4 ± 9,7 (p = NS), y la significación estadística se alcanzó a partir de los 30min posteriores a su instauración. En un 76% de los casos aparecieron alteraciones del registro cardiotocográfico en los primeros 120 min tras la perfusión analgésica. Conclusiones: La disminución de la saturación arterial de oxígeno a partir de los 30 min postepidural puede estar relacionada con la administración de analgésicos por vía epidural (AU)


Objective: To evaluate the influence of maternalepidural analgesia on fetal oxygen saturation (SpO2) and fetal heart rate (FHR) patterns during labor. Material and methods: We performed a prospective study in 50 pregnant women. During labor, epidural analgesia was administered and the women were monitored by means of cardiotocography (CTG) and fetal pulse oximetry, using a Nellcor FS-14® sensor. Results: The mean SpO2 value before analgesia administration was 48.5 ± 7.8%. During the first 15 minutes after administration, this value was 47.4 ± 9.7 (p: NS). A statistically significant decrease in SpO2 was found 30 minutes after initiation of epidural analgesia in 76 % of the patients, alterations in the CTG appeared during the first 120 minutes after maternal epidural analgesia. Conclusions: The decrease in SpO2 30 minutes after administration of epidural analgesia could be influenced by the use of epidural analgesic drugs (AU)


Asunto(s)
Humanos , Femenino , Embarazo , Analgesia Epidural/métodos , Analgesia Epidural/tendencias , Frecuencia Cardíaca/fisiología , Monitoreo Fetal/métodos , Fentanilo/farmacología , Fentanilo/uso terapéutico , Rotura Prematura de Membranas Fetales/complicaciones , Analgesia Obstétrica/métodos , Analgesia Obstétrica/tendencias , Frecuencia Cardíaca , Desarrollo Embrionario y Fetal/fisiología , Sufrimiento Fetal/fisiopatología , Estudios Prospectivos
16.
Langmuir ; 24(5): 1823-8, 2008 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-18225932

RESUMEN

In this work, a DMPA Langmuir monolayer at the air/water interface was studied by molecular dynamics simulations. Thus, an atomistic picture of a Langmuir monolayer was drawn from its expanded gas phase to its final solid condensed one. In this sense, some properties of monolayers that were traditionally poorly or even not reproduced in computer simulations, such as lipid domain formation or pressure-area per lipid isotherm, were properly reproduced in this work. Thus, the physical laws that control the lipid domain formation in the gas phase and the structure of lipid monolayers from the gas to solid condensed phase were studied. Thanks to the atomistic information provided by the molecular dynamics simulations, we were able to add valuable information to the experimental description of these processes and to access experimental data related to the lipid monolayers in their expanded phase, which is difficult or inaccessible to study by experimental techniques. In this sense, properties such as lipids head hydration and lipid structure were studied.


Asunto(s)
Compuestos de Anilina/química , Simulación por Computador , Modelos Químicos , Agua/química , Aire , Lípidos/química , Transición de Fase , Liposomas Unilamelares/química
17.
J Phys Chem B ; 111(49): 13726-33, 2007 Dec 13.
Artículo en Inglés | MEDLINE | ID: mdl-18004836

RESUMEN

Understanding the structure and dynamics of phospholipid bilayers is of fundamental relevance in biophysics, biochemistry, and chemical physics. Lipid Langmuir monolayers are used as a model of lipid bilayers, because they are much more easily studied experimentally, although some authors question the validity of this model. With the aim of throwing light on this debate, we used molecular dynamics simulations to obtain an atomistic description of a membrane of dimyristoylphosphatidic acid under different surface pressures. Our results show that at low surface pressure the interdigitation between opposite lipids (that is, back-to-back interactions) controls the system structure. In this setting and due to the absence of this effect in the Langmuir monolayers, the behavior between these two systems differs considerably. However, when the surface pressure increases the lipid interdigitation diminishes and so monolayer and bilayer behavior converges. In this work, four computer simulations were carried out, subjecting the phospholipids to lateral pressures ranging from 0.17 to 40 mN/m. The phospholipids were studied in their charged state because this approach is closer to the experimental situation. Special attention was paid to validating our simulation results by comparison with available experimental data, therebeing in general excellent agreement between experimental and simulation data. In addition, the properties of the lipid/solution interface associated with the lipid barometric phase transition were studied.


Asunto(s)
Compuestos de Anilina/química , Membrana Dobles de Lípidos , Modelos Teóricos , Agua/química
18.
Physiol Behav ; 69(3): 333-44, 2000 May.
Artículo en Inglés | MEDLINE | ID: mdl-10869600

RESUMEN

Neonatal monosodium glutamate (MSG) treatment has been associated with dysfunctions in stress responses. Therefore, the present study aimed at examining the acoustic startle response (ASR) in MSG-treated rats and the effects of fetal neural transplantation. Male and female rats were given MSG (4 mg/g) or saline on alternate days from days 2-10 after birth. To determine whether fetal transplants could reverse behavioral impairments observed in MSG-treated rats, at 12 days of age MSG-treated rats received either arcuate nucleus (AN), cortical fetal grafts, or sham surgery into the third ventricle. ASR amplitude was measured at 35-40 days of age, and again in adulthood. MSG produced the expected decrease in the density of hypothalamic neuropeptide Y (NPY) and tyrosine hydroxylase (TH) in the AN area. Corticotropin-releasing factor (CRF) neurons/fibers were not affected by MSG. Pituitary atrophy was observed in all MSG rats. We report a permanent increase in the amplitude and reduction in short-term habituation of ASR in all MSG-treated rats. No effect was observed on long-term habituation in male rats. Cortical, but not AN tissue significantly reduced the magnitude of ASR in MSG animals. The results are discussed in terms of the central pathways mediating ASR, in particular hypothalamo-amygdala connections. It is considered that nonspecific factors mediate recovery produced by cortical tissue grafts, as observed in other models of neural transplantation.


Asunto(s)
Trasplante de Tejido Encefálico/fisiología , Reflejo de Sobresalto/efectos de los fármacos , Glutamato de Sodio/farmacología , Animales , Animales Recién Nacidos , Encéfalo/anatomía & histología , Hormona Liberadora de Corticotropina/farmacología , Femenino , Habituación Psicofisiológica/fisiología , Inmunohistoquímica , Masculino , Neuropéptido Y/farmacología , Tamaño de los Órganos , Hipófisis/anatomía & histología , Ratas , Ratas Sprague-Dawley , Tirosina 3-Monooxigenasa/metabolismo
19.
J Biol Rhythms ; 15(2): 103-11, 2000 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-10762028

RESUMEN

The authors have described a subregion of the hamster hypothalamic suprachiasmatic nucleus (SCN) containing cells that are immunopositive for the cytosolic calcium-binding protein, Calbindin-D28K (CaBP). Several lines of evidence indicate that this region may constitute the site of the pacemaker cells that are responsible for the regulation of circadian locomotor rhythms. First, 79% of the CaBP-immunoreactive (ir) neurons express Fos in response to photic stimulation, indicating that they are close to or part of the input pathway to pacemakers. Second, at the light microscopy level, retinal terminals innervate the CaBP subnucleus. Finally, destruction of this subnucleus renders animals arrhythmic in locomotor activity. In this study, the authors examined the ultrastructural relationship between cholera toxin (CTbeta) labeled retinal fibers and the CaBP-ir subregion within the hamster SCN. CTbeta-ir retinal terminals make primarily axo-somatic, symmetric, synaptic contacts with CaBP-ir perikarya. In addition, retinal terminals form synapses with CaBP processes as well as with unidentified profiles. There are also complex interactions between retinal terminals, CaBP perikarya, and unidentified profiles. Given that axo-somatic synaptic input has a more potent influence on a cell's electrical activity than does axo-dendritic synaptic input, cells of the CaBP subregion of the SCN are ideally suited to respond rapidly to photic stimulation to reset circadian pacemakers.


Asunto(s)
Retina/fisiología , Proteína G de Unión al Calcio S100/metabolismo , Núcleo Supraquiasmático/metabolismo , Animales , Calbindinas , Toxina del Cólera , Cricetinae , Dendritas/fisiología , Masculino , Terminaciones Nerviosas/metabolismo , Terminaciones Nerviosas/ultraestructura , Retina/metabolismo , Retina/ultraestructura , Núcleo Supraquiasmático/citología , Núcleo Supraquiasmático/fisiología , Núcleo Supraquiasmático/ultraestructura , Sinapsis/fisiología
20.
Brain Res Dev Brain Res ; 116(1): 59-68, 1999 Aug 05.
Artículo en Inglés | MEDLINE | ID: mdl-10446347

RESUMEN

Status epilepticus and repeated seizures have age-dependent morphological and neurophysiological alterations in the hippocampus. In the present study, effects of flurothyl-induced status epilepticus were examined in awake and free moving immature (2 weeks old) and adult rats. Without exception, adult rats died of respiratory arrest before the onset of status epilepticus. We were unable to find a concentration of flurothyl that produced status epilepticus and a low mortality in adult rats. In contrast, immature rats survived flurothyl status epilepticus for up to 60 min with a very low mortality. In rat pups, behavioral manifestations correlated with electrographic seizures in both the cortex and hippocampus. Neuropathological damage (cell loss, pyknotic cells or gliosis) was not observed in the immature hippocampus, thalamus, amygdala, substantia nigra or cortex at 24 h, 2 days or 2 weeks after status epilepticus. In addition, no aberrant mossy fiber reorganization or decrease in cells counts were observed in the hippocampus. Young rats did not show alterations in paired-pulse perforant path inhibition following flurothyl status epilepticus. The present findings are consistent with studies in other seizure models, indicating that immature rats are highly resistant to seizure-induced changes.


Asunto(s)
Conducta Animal/efectos de los fármacos , Corteza Cerebral/efectos de los fármacos , Convulsivantes/toxicidad , Electroencefalografía/efectos de los fármacos , Hipocampo/efectos de los fármacos , Estado Epiléptico/inducido químicamente , Animales , Corteza Cerebral/patología , Corteza Cerebral/fisiopatología , Flurotilo/toxicidad , Hipocampo/patología , Hipocampo/fisiopatología , Masculino , Fibras Musgosas del Hipocampo/efectos de los fármacos , Fibras Musgosas del Hipocampo/patología , Neuronas/efectos de los fármacos , Neuronas/patología , Ratas , Ratas Sprague-Dawley , Tinción con Nitrato de Plata , Estado Epiléptico/patología , Estado Epiléptico/fisiopatología , Estado Epiléptico/psicología
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