207 research outputs found
Unique Scanning Electron Microscopic Features of Hairy Cells in Hairy-Cell Leukemia. A Review and Current Status
Past scanning electron microscopy (SEM) reports demonstrated cell surface undulations, ridges, folds, and ruffles to support the monocytic/histiocytic nature of hairy-cell leukemia (HCL) cells. On the other hand, SEM studies illustrating spikes, villi, and microvilli on the cell surfaces favored the lymphocytic nature of hairy cells (HCs). The evidence for the \u27hybrid\u27 nature of the HCs has emerged from the demonstration of concurrent display of monocytic (ruffles) and lymphocytic (microvilli) surface features on each cell. Utilizing improved methods of sampling, fixation, and drying, the current status is that all HCs display microvilli and ruffles simultaneously. However, two distinct morphological types of HCs are acknowledged: cells showing ruffled areas next to clumps of microvilli (type A), and cells displaying microvilli interspersed among ruffles (type B) . Each of the HCL cases reported in our studies had cells with either type A or type B surface features. Amazingly, these unique SEM features correlate well with the prevalent trend to classify HCs as malignant (villous) B-lymphocytes imitating (ruffled) monocytes in some functional respects
Interferon-Induced Surface Alterations in Hairy Cells. A Review
Hairy cells (HCs), derived from the peripheral blood and spleen of hairy cell leukemia (HCL) patients, constantly displayed both ruffles and microvilli. HCs which were kept in culture for up to three days exhibited extremely polarized and active surfaces with elongated microvilli and exaggerated spiked ruffles. Cells derived from 11 cases of HCL were treated with alpha-interferon (IFN) in-vitro and examined by immuno -scanning electron microscopy (immuno-SEM). In 8 cases, up to one-third of the IFN-treated hairy cells displayed deformed surfaces with bubbling membrane and markedly villous bud-like formations. Monoclonal antibodies (MoAb), used in conjunction with immuno-qold labeling, facilitated better correlation between these morphological changes and the immunological profiles of the cells before and after interferon treatment in-vitro. Immuno-SEM analyses revealed no remarkable changes in the labeling of HCs with Leu-14 and Leu-MS MoAbs before and after IFN treatment, even in cases showing membrane changes. However, a significant increase in the labeling intensity for HLA-DR and HLA-DQ was noticed in HCs from cases where IFN-induced membrane changes were evident. A review of the literature on membrane changes in IFN-treated cells proposes that such immuno-ultrastructural alterations might reflect unique interferon-induced membrane reorganization in the target malignant cells
Topical Modes in the Preparation of Human Spleen Specimens for Routine Scanning Electron Microscopy Studies
Various preparatory techniques were used to improve scanning electron microscopy images of the fine structure of vascular, cellular, and cordal-reticular components of normal human spleens. The progressive method of fixation (GTGO) applied in the present study, allowed air drying of the tissues and rendered the specimens conductive even in newly fractured surfaces. Vascular perfusion proved necessary only in studies of the splenic blood vessels, while a simple immersion of tissue blocks in the washing solution resulted in better images of the white pulps. Interstitial (trans-splenic) perfusion was found to be superior to vascular perfusion for routine preparation of spleen tissues, and freeze-cracking did not necessarily lead to improved images of the specimen\u27s surfaces. Combined with proper washing and shaping protocols, the GTGO procedure is shown to be a superior mode of specimen preparation, abolishing most traditional artifacts and obtaining clear images of the complex splenic tissue
Geometric phase in open systems
We calculate the geometric phase associated to the evolution of a system
subjected to decoherence through a quantum-jump approach. The method is general
and can be applied to many different physical systems. As examples, two main
source of decoherence are considered: dephasing and spontaneous decay. We show
that the geometric phase is completely insensitive to the former, i.e. it is
independent of the number of jumps determined by the dephasing operator.Comment: 4 pages, 2 figures, RevTe
Berry's Phase in the Presence of a Stochastically Evolving Environment: A Geometric Mechanism for Energy-Level Broadening
The generic Berry phase scenario in which a two-level system is coupled to a
second system whose dynamical coordinate is slowly-varying is generalized to
allow for stochastic evolution of the slow system. The stochastic behavior is
produced by coupling the slow system to a heat resevoir which is modeled by a
bath of harmonic oscillators initially in equilibrium at temperature T, and
whose spectral density has a bandwidth which is small compared to the
energy-level spacing of the fast system. The well-known energy-level shifts
produced by Berry's phase in the fast system, in conjunction with the
stochastic motion of the slow system, leads to a broadening of the fast system
energy-levels. In the limit of strong damping and sufficiently low temperature,
we determine the degree of level-broadening analytically, and show that the
slow system dynamics satisfies a Langevin equation in which Lorentz-like and
electric-like forces appear as a consequence of geometrical effects. We also
determine the average energy-level shift produced in the fast system by this
mechanism.Comment: 29 pages, RevTex, submitted to Phys. Rev.
Solving spin quantum-master equations with matrix continued-fraction methods: application to superparamagnets
We implement continued-fraction techniques to solve exactly quantum master
equations for a spin with arbitrary S coupled to a (bosonic) thermal bath. The
full spin density matrix is obtained, so that along with relaxation and
thermoactivation, coherent dynamics is included (precession, tunnel, etc.). The
method is applied to study isotropic spins and spins in a bistable anisotropy
potential (superparamagnets). We present examples of static response, the
dynamical susceptibility including the contribution of the different relaxation
modes, and of spin resonance in transverse fields.Comment: Resubmitted to J. Phys. A: Math. Gen. Some rewriting here and there.
Discussion on positivity in App.D3 at request of one refere
In-situ upgrading of Napier grass pyrolysis vapour over microporous and hierarchical mesoporous zeolites
This study presents in-situ upgrading of pyrolysis
vapour derived from Napier grass over microporous and
mesoporous ZSM-5 catalysts. It evaluates effect of process
variables such catalyst–biomass ratio and catalyst type in
a vertical fixed bed pyrolysis system at 600 °C, 50 °C/min
under 5 L/min nitrogen flow. Increasing catalyst–biomass
ratio during the catalytic process with microporous structure
reduced production of organic phase bio-oil by approximately
7.0 wt%. Using mesoporous catalyst promoted
nearly 4.0 wt% higher organic yield relative to microporous
catalyst, which translate to only about 3.0 wt% reduction
in organic phase compared to the yield of organic phase
from non-catalytic process. GC–MS analysis of bio-oil
organic phase revealed maximum degree of deoxygenation
of about 36.9% with microporous catalyst compared to
the mesoporous catalysts, which had between 39 and 43%.
Mesoporous catalysts promoted production olefins and
alkanes, normal phenol, monoaromatic hydrocarbons while
microporous catalyst favoured the production of alkenes
and polyaromatic hydrocarbons. There was no significant increase in the production of normal phenols over microporous catalyst due to its inability to transform the methoxyphenols and methoxy aromatics. This study demonstrated that upgrading of Napier grass pyrolysis vapour over mesoporous ZSM-5 produced bio-oil with improved physicochemical properties
Developmental Trajectories in Siblings of Children with Autism: Cognition and Language from 4 Months to 7 Years
We compared the cognitive and language development at 4, 14, 24, 36, 54 months, and 7 years of siblings of children with autism (SIBS-A) to that of siblings of children with typical development (SIBS-TD) using growth curve analyses. At 7 years, 40% of the SIBS-A, compared to 16% of SIBS-TD, were identified with cognitive, language and/or academic difficulties, identified using direct tests and/or parental reports. This sub-group was identified as SIBS-A-broad phenotype (BP). Results indicated that early language scores (14–54 months), but not cognitive scores of SIBS-A-BP and SIBS-A-nonBP were significantly lower compared to the language scores of SIBS-TD, and that the rate of development was also significantly different, thus pinpointing language as a major area of difficulty for SIBS-A during the preschool years
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