Search PubMed⌕ Search

Biomedical subjects

D Long

Publications and source records attributed to D Long.

At least 19 recordsLinked to original sources
PubMed2006

Hypoxia/reoxygenation up-regulated the expression of death receptor 5 and enhanced apoptosis in human hepatocyte line.

OBJECTIVES: Ischemia-reperfusion injury (IRI) is a key factor that contributes to early and late dysfunction of liver graft. Although we have known that hepatocytes express death receptors for tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), the effects of TRAIL on hypoxia/reoxygenation (H/R)-mediated apoptosis are unclear. This study sought to examine the effects of H/R on TRAIL cytotoxicity, as a cause of primary hepatic graft dysfunction, delayed graft refunction, and chronic graft dysfunction. METHODS: Using an hepatocyte H/R model in vitro to mimic IRI in the grafted liver, normal human hepatocytes HL-7702 were exposed to hypoxia for 5 hours then reoxygenated for 0, 2, 4, 6, or 20 hours. In another experiment, hepatocytes were exposed to hypoxia for 0, 2, 4, 8, or 20 hours. Expressions of TRAIL-R2/Death receptor 5 (DR5) mRNA were measured by semiquantitative reverse-transcriptase polymerase chain reactions. After 16 hours of hypoxia, human hepatocytes were treated with TRAIL in different concentrations for 5 hours. The death of hepatocytes was confirmed by flow cytometer and methyl thiazolyl tetrazolium analysis. RESULT: After 5-hour hypoxia, the expressions of DR5 mRNA increased at all times of reoxygenation. DR5 mRNA was up-regulated from 0 hour after reoxygenation, reaching a peak value at 2 hours after reoxygenation compared with the normoxia cultured cells. Moreover, DR5 mRNA was up-regulated gradually following prolonged hypoxia. TRAIL-mediated cell killing was concentration-dependent being greater in the hypoxia treatment group compared to the normoxia group. CONCLUSIONS: H/R up-regulated the expression of DR5 and enhanced TRAIL-mediated apoptosis in an human hepatocyte line. The TRAIL pathway might play a critical role in hepatocyte apoptosis induced by IRI.

Apoptosis↗
PubMed2004

Heterogeneous nature of the dynamics and glass transition in thin polymer films.

Recent experiments have demonstrated that the dynamics in liquids close to and below the glass transition temperature is strongly heterogeneous, on the scale of a few nanometers. We use here a model proposed recently for explaining these features, and show that the heterogeneous nature of the dynamics has important consequences when considering the dynamics of thin films. We show how the dominant relaxation time in a thin film is changed as compared to the bulk, as a function of the thickness, the interaction energy with the substrate, and the temperature. The corresponding time scales cover the so-called VFT (or WLF) regime and vary between 10(-8) s to 10(4) s typically. In the absence of interaction, our model allows for interpreting suspended films experiments, in the case of small polymers for which the data do not depend on the polymer weight. The interaction leads to an increase of T(g) for an interaction per monomer of the order of the thermal energy T. This increase saturates at the value corresponding to strongly interacting films for adsorption energies slightly larger and still of order T. In particular, we predict that the T(g) shift can be non-monotonous as a function of the film thickness, in the case of intermediate interaction strength.

Journal Article↗
PubMed2003

The cold-water coral Lophelia pertusa (Scleractinia) and enigmatic seabed mounds along the north-east Atlantic margin: are they related?

In this study, an updated distribution of Lophelia pertusa between the Porcupine Seabight and Norwegian shelf is presented. It seems unlikely that enigmatic mound structures observed at water depths of more than 570 m during acoustic seabed surveys, particularly to the west of the Shetland Islands, are related to the occurrence of L. pertusa. At these depths in the Faroe-Shetland Channel, the predominant influence of cold Arctic water precludes its growth. Iceberg dumpsites are also considered unlikely explanations for the origin of these mounds, and they are interpreted as most likely to be related to the release of fluids at the seabed. When mound structures were investigated, no scleractinian corals were recovered at water depths >500 m. This study shows the importance of seabed temperature as an environmental control on cold-water coral distribution. The significance of cold-water coral habitats in sustaining high levels of local-scale biodiversity is now becoming apparent in parallel with increased hydrocarbon extraction and fishing activity beyond the shelf edge. There is growing evidence that these areas have been marked by the passage of deep-water trawls. It seems likely that trawling activity has already reduced the extent of cold-water coral distribution in this region of the north-east Atlantic.

Animals↗
PubMed2003

Dexamphetamine treatment in stroke.

Reducing disability and dependency after a stroke is an important clinical objective. We examine what is known about the use of dexamphetamine in patients recovering from an acute stroke, and consider whether further clinical studies should be undertaken. Dexamphetamine has repeatedly been shown to enhance recovery after experimental brain injury in animals, the best effects being seen when dexamphetamine is combined with lesion-specific motor training or sensory stimulation. Postulated mechanisms for these beneficial effects in animals are in keeping with contemporary theories of neurophysiological rehabilitation in man. There have been few clinical studies of dexamphetamine during rehabilitation after an acute stroke. Four controlled trials demonstrated a tendency to an improved outcome when dexamphetamine was paired with therapy and administered 3-30 days after an ischaemic stroke. However, clinical studies to date have been small, included only highly selected patients, and have not addressed possible confounding effects of the drug on mood and untreated depression. Dexamphetamine has previously been used under supervision in medically ill patients and appears to be safe and well-tolerated. There is a need for well-designed studies to assess further the safety and efficacy of dexamphetamine in rehabilitation after stroke.

Animals↗
PubMed2003

The crossover from 2D to 3D percolation: theory and numerical simulations.

We describe here the crossover between 2D and 3D percolation, which we do on cubic and square lattices. As in all problems of critical phenomena, the quantities of interest can be expressed as power laws of /p-pc(h)/, where pc(h) and h are the percolation threshold and the thickness of the film, respectively. When these quantities are considered on the scale of the thickness h of the films, the corresponding numerical prefactors are of order one. However, for many problems, the scale of interest is the elementary one. The corresponding expressions contain then prefactors in power of h which we calculate. For instance, we show that the mass distribution n(m) of the clusters is given by a master function of h(-D+1/sigma2nu3)/p-pc(h)/1/sigma2(m), where h is the thickness of the film and D, nu3, sigma2 are tabulated 2D and 3D critical exponents. We consider also the size R2( m) of the clusters as a function of their mass m, for which we provide both scaling laws and numerical data. Therefore, any property corresponding to a given moment of mass and size can be obtained from our results. These results might be useful for describing transport properties, such as electric conductivity, or the mechanical properties of thin films made of disordered materials.

Journal Article↗
PubMed2002

Heterogeneous dynamics at the glass transition in van der Waals liquids: determination of the characteristic scale.

Recent experiments have demonstrated that the dynamics in liquids close to the glass transition temperature is strongly heterogeneous. The characteristic size of these heterogeneities has been measured to be a few nanometers at Tg. We extend here a recent model for describing the heterogeneous nature of the dynamics which allows both to derive this length scale and the right orders of magnitude of the heterogeneities of the dynamics close to the glass transition. Our model allows then to interpret quantitatively small probes diffusion experiments.

Journal Article↗
PubMed2000

ACAULIS5, an Arabidopsis gene required for stem elongation, encodes a spermine synthase.

Polyamines have been implicated in a wide range of biological processes, including growth and development in bacteria and animals, but their function in higher plants is unclear. Here we show that the Arabidopsis: ACAULIS5 (ACL5) gene, whose inactivation causes a defect in the elongation of stem internodes by reducing cell expansion, encodes a protein that shares sequence similarity with the polyamine biosynthetic enzymes spermidine synthase and spermine synthase. Expression of the recombinant ACL5 protein in Escherichia coli showed that ACL5 possesses spermine synthase activity. Restoration of the acl5 mutant phenotype by somatic reversion of a transposon-induced allele suggests a non-cell-autonomous function for the ACL5 gene product. We also found that expression of the ACL5 cDNA under the control of a heat shock gene promoter in acl5 mutant plants restores the phenotype in a heat shock-dependent manner. The results of the experiments showed that polyamines play an essential role in promotion of internode elongation through cell expansion in Arabidopsis: We discuss the relationships to plant growth regulators such as auxin and gibberellins that have related functions.

Alleles↗
PubMed2000

Changes in a murine leukemia virus (MLV) receptor encoded by an alphavirus vector during passage in cells expressing the MLV envelope.

We constructed alphavirus vectors encoding the ecotropic murine leukemia virus (MLV) receptor mCAT1. Cells electroporated with these vector RNAs expressed mCAT1 protein and fused with cells that expressed a fusogenic form of the MLV envelope on the cell surface. Electroporated cells also released submicron particles that were infectious in envelope-expressing cells. Infection resulted in giant syncytia that could be enumerated by plaque assay. Cell-free supernatants could be serially passaged and contained up to 10(4) infectious units/ml. To determine whether repeated passage would select for functional variants of the receptor, we analyzed mCAT1 amplified by RT-PCR after 12 serial passages. Several amino acid substitutions were identified that encoded functional receptor variants. In independent experiments, variants containing an isoleucine or a leucine instead of a phenylalanine at position 224 in the third extracellular domain of the receptor arose spontaneously and outgrew the parental vector, indicating that mutations at this site are highly selected in this system. This region of the receptor has previously been implicated in the envelope-receptor interaction. This alphavirus vector system provides a novel method for generating and selecting functional variants of viral receptors

Alphavirus↗
PubMed2000

Announcements

Explore the source record for details and available documents.

Journal Article↗
PubMed2000

Announcements

Explore the source record for details and available documents.

Journal Article↗
PubMed2000

[Determination of scalp ER and AR of patients with male pattern baldness and the effects of hair transplantation on them].

OBJECTIVE: To study the role of sex hormone receptor capacity of the scalp in male pattern baldness(MPB). METHODS: Estrogen receptor(ER) and androgen receptor(AR) assays were performed using fluorescent steroid hormone conjugate technique (FSHCT) in hairness and bald scalp in 8 patients with MPB. Changes of ER and AR capacity in recipient and donor sites of hair transplantation in MPB scalps were examined. RESULTS: The percentage of AR staining cells in the outer root sheath, sebaceous gland and bulb papilla of the lesional scalps was significantly higher than that of hairness scalps (P < 0.01). The percentage of ER positive cells in the outer root sheath of lesional scalps increased significantly (P < 0.01). CONCLUSION: Changes of contents of sex hormone receptors(SHR) in some sensitive area of the scalp induce MPB.

Adult↗
PubMed1999

Electroosmotic Flows Created by Surface Defects in Capillary Electrophoresis.

We compute the electroosmotic flow in nonuniformly charged planar and cylindrical capillaries for the limit of low-Reynolds-number flows and thin Debye layers. Analytical formulae for the velocity field are provided for the general case of an arbitrary surface inhomogeneity but we also focus on various specific defect geometries. Many important features can be obtained from the simple lubrication approximation. The pressure jump induced by the presence of such surface defects is calculated and the possible occurrence of recirculating flows is discussed, as are effects of the flow perturbations on dispersion in capillary electrophoresis. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Sweet's syndrome and erythema nodosum: the simultaneous occurrence of 2 reactive dermatoses.

BACKGROUND: The simultaneous occurrence of Sweet's syndrome (SS) and erythema nodosum (EN) in 1 patient is rare. Our review of the literature revealed only 11 biopsy-proved cases in which the 2 reactive dermatoses occurred together. None were associated with an underlying malignant neoplasm. OBSERVATIONS: We report a biopsy-proved case of SS and EN occurring simultaneously in a patient with an underlying malignant neoplasm (specifically, acute myelogenous leukemia). We also report another biopsy-proved case of SS and EN occurring simultaneously in a patient with underlying Crohn's disease. CONCLUSIONS: The simultaneous occurrence of SS and EN in 1 patient is rarely reported. Both disorders are reactive dermatoses that share many overlapping features. Although individually distinctive, SS and EN are also part of a growing continuum of reactive dermatoses. Our expanded understanding of the similarities and simultaneous manifestation of SS and EN may help us in the future to identify a common underlying mechanism of pathogenesis.

Adult↗
PubMed1999

[The value of anesthesia consultation in relation to the single preanesthetic visit].

OBJECTIVE: In France, a preanaesthetic assessment (PAA) several days prior to hospital admission for a scheduled surgical or diagnostic procedure under anaesthesia, associated with a preanaesthetic visit (PAV) the day before, are compulsory. This study aimed at comparing the benefits of PAA with those of a PAV not preceded by a PAA. STUDY DESIGN: Prospective, controlled, randomized study. PATIENTS: The study included 296 patients undergoing either a urologic, or ophthalmologic, or ENT procedure, randomly allocated either to a PAA (followed by a PAV) group or a PAV (without previous PAA) group. METHODS: The main criterion of comparison was the duration of preanaesthetic hospital stay and the secondary criteria were the incidence of procedure postponements and patients' satisfaction respectively. RESULTS: In the PAA group, the preanaesthetic hospital stay was shorter by 0.4 days (P = 0.001). Out of the 19 postponed procedures (7%), the cause of postponement was a medical one in 15 patients: 13 in the PAV group and 2 in the PAA group respectively (P = 0.009). The PAA was not considered as a constraint by most patients. CONCLUSION: The PAA shortens the duration of preanaesthetic hospital stay and decreases the incidence of procedures postponed for a medical cause.

Analysis of Variance↗
PubMed1999

The heat moisture exchange device (HME) in neonatal ventilation.

The objective of this study was to compare the safety and efficacy of the Heat Moisture Exchange (HME) device with conventional humidification in neonates. Sixty-four neonates were randomized at intubation to receive conventional humidification (CH) (n = 34) or HME, via a Neoaid device (n = 30). Groups were compared for intrinsic characteristics and outcome variables. Data were assumed nonparametric and analyzed by Mann-Whitney and Fisher's Exact test. No significant differences were found in group characteristics or outcome variables. Trends were noted for documented patent ductus arteriosus (PDA), endotracheal tube blockage, and positive endotracheal aspirate culture. Rate of pneumothorax 2/34 (CH) versus 4/30 (HME) (p = 0.4); rate of tube blockage 3/34 (CH) versus 2/30 (HME) (p = 1.0); rate of PDA 8/34 (CH) versus 14/30 (HME) (p = 0.093) and rate of endotracheal colonisation 1 7/34 (CH) versus 9/30 (HME) (p = 0.17). No significant difference was found for duration of ventilation or period in greater than 40% oxygen between the two groups. There were no significant outcome differences between CH and HME. The HME device was cost-effective and simple to use. A larger multicenter trial is warranted to confirm the efficacy of HME.

Equipment Design↗
PubMed1999

[Prevention and treatment of eyelid retraction and ectropion following lower eyelid blepharoplasty with tarsal tuck procedure].

OBJECTIVE: To prevent or decrease eyelid retraction and ectropion following lower eyelid blepharoplasty. METHODS: The tarsal tuck procedure was performed during lower eyelid blepharoplasty to tighten the lower eyelid. This method had been used since 1991. RESULTS: After the operation, the lower eyelid was tensional and steady. The complications of eyelid retraction and ectropion were diminished. CONCLUSION: The pathologic basis of the eyelid bag is that the supporting tissues become lax so that the lower eyelid and lateral canthus move downwards. The exact aim of the tarsal tuck procedure is to correct these pathologic changes.

Blepharoplasty↗