bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective laser nano‐thermolysis of human leukemia cells with microbubbles generated around clusters of gold nanoparticles
Authors: Lapotko Dmitri O. , Lukianova Ekaterina , Oraevsky Alexander A. 
Published: May 2006

AbstractBackground and ObjectivePreviously reported studies on laser nano‐thermolysis of cancerous cells demonstrated insufficient efficacy and specificity of malignant cell damage. Safety, that is, absence of damage to normal cells in the course of the laser thermolysis was also low due to less than optimal protocol of cancer cell targeting with nanoparticles (NP). The objective of this study was two‐fold: to optimize NP targeting to real tumor (human) cells and to better understand physical mechanisms of cell damage for improved control of the laser ablation.Study Design/Materials and MethodsWe have suggested (1) two‐stage targeting method to form clusters of light‐absorbing gold NPs selectively in target cells, and (2) the cell damage mechanism through laser‐induced generation of vapor bubbles around NP clusters. Experimental investigation of laser nano‐thermolysis of leukemia cells was performed using 30 nm spherical gold nanoparticles as a light absorbing agent, and photothermal and fluorescent microscopies as well as flow cytometry as methods to monitor microbubble formation and resulting damage of leukemia cells in human bone marrow specimens.ResultsNP clusters were formed and visualized using fluorescence microscopy at cell membranes and in cytoplasm of B‐lymphoblasts. Laser irradiation of cells (532 nm, 10 nanoseconds, 0.6 J/cm2) induced microbubbles selectively in leukemia cells with large clusters, but not in cells with single NPs or small clusters. Quantitative analysis demonstrated that only 0.1%–1.5% of tumor cells and 77%–84% of normal bone marrow cells survived laser pulse.ConclusionsTwo‐stage cell targeting method permits formation of NP clusters selectively in diagnosis‐specific tumor cells. The clusters serve as effective sources of photothermally‐induced microbubbles, which kill individual target cells after a single laser pulse. The laser fluence threshold for generation of microbubbles is inversely proportional to the volume of NP clusters. Lasers Surg. Med. 38:631–642, 2006. © 2006 Wiley‐Liss, Inc.
Sperm incorporation and pronuclear development during fertilization in the freshwater bivalve Dreissena polymorpha
Authors: Misamore Michael J. , Stein Katheryn K. , Lynn John W. 
Published: May 2006

AbstractThe invasive zebra mussel, Dreissena polymorpha (D. polymorpha), is proving to be a valuable model for understanding general mechanisms of fertilization, particularly regarding sperm incorporation. In the present study, we tracked the various components of the fertilizing sperm of D. polymorpha during sperm incorporation. During fertilization the sperm membrane remains associated with the egg surface as a distinct patch that disperses over time. This patch marked the site of sperm entry that occurs predominately on the CD blastomere. Taking advantage of the relatively unpigmented cytoplasm, real‐time observations were made of the incorporated sperm nucleus as it decondensed and reformed as a developing pronucleus. Pronuclear enlargement occurred progressively and at rates comparable with previously reported fixed‐time point observations. Sperm mitochondria were incorporated and separated from the sperm along the leading edge of the decondensing nucleus. Sperm mitochondria labeled with Mitotracker Green® remained predominately associated with the CD blastomere following first cleavage and could be tracked to the 16‐cell stage before the fluorescence was too faint to detect. Additionally, the demembranated sperm axoneme was incorporated, separated during nuclear decondensation, and remained visible in the egg cytoplasm up to 30 min postinsemination (PI). The present study provides one of the most complete descriptions of incorporation on multiple sperm components into the egg and coordinates fixed‐time point observations with real‐time observations of sperm within the remarkably transparent egg cytoplasm of zebra mussels. Mol. Reprod. Dev. 1140–1148, 2006. © 2006 Wiley‐Liss, Inc.
Maternal housekeeping proteins translated during bovine oocyte maturation and early embryo development
Authors: Massicotte Lyne , Coenen Karine , Mourot Marina , Sirard Marc‐André 
Published: May 2006

AbstractProtein synthesis from maternal mRNA is needed to sustain oocyte maturation and embryo development prior to the maternal‐embryonic transition (MET). Therefore, proteins that are expressed throughout this time are important and may be considered as maternal housekeeping proteins (MHKP). Our objectives were first, identify the translated protein patterns of bovine embryo development and secondly, determine the MHKP. Proteins synthesized during oocyte maturation and embryo development (2, 4 and 8‐cell stages) were labeled using [S35]‐Met and [S35]‐Cys, and visualized by 2‐DE. Embryos were cultured with α‐amanitine to inhibit new transcription. Only 46 proteins were present throughout all stages. Ten spots were identified by MALDI‐TOF and MS/MS: HSC71; HSP70; CypA; UCH‐L1; GSTM5; Cct5; E‐FABP; 2,3‐BPGM, ubiquitin‐conjugating enzyme E2D3; and β‐actin/γ‐actin. A new method called in silico protein identification confirmation was developed using EST databases. This method is a promising approach for use in rare tissue or from species with an incomplete protein database. This study has revealed that the translated protein patterns show a transition that brings the embryo to the MET. The needs in translated proteins between oocyte maturation and embryo development are different. In summary, this study represents the bases for future proteomics studies on bovine oocytes and embryos.
Prevention of dyskinesia by an NMDA receptor antagonist in MPTP monkeys: Effect on adenosine A2Areceptors
Authors: Morissette Marc , Dridi Mehdi , Calon Frédéric , Tahar Abdallah Hadj , Meltzer Leonard T. , Bédard Paul J. , Di Paolo Thérèse 
Published: May 2006

AbstractAdenosine A2Areceptors (A2AR) have received increasing attention for the treatment ofL‐DOPA‐induced dyskinesias in Parkinson disease. In the present study, A2AR messenger RNA (mRNA) and receptor‐specific binding in the brain of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) monkeys were studied after treatment withL‐DOPA and a selective NR1A/2B NMDA receptor antagonist, CI‐1041. Four MPTP monkeys receivedL‐DOPA/benserazide and all developed dyskinesias, whereas among the four MPTP monkeys who additionally received CI‐1041, only one developed mild dyskinesias. Four normal monkeys and four MPTP‐treated monkeys were also studied. All MPTP monkeys had similar striatal dopamine (DA) denervation. A2AR mRNA levels, measured by in situ hybridization, were increased in the rostral lateral caudate and putamen of saline‐treated MPTP monkeys as well as in the caudal lateral and medial putamen when compared with those of controls. A2AR mRNA levels remained elevated in the rostral caudate and putamen ofL‐DOPA‐treated MPTP monkeys when compared with those of controls. A2AR mRNA levels ofL‐DOPA + CI‐1041‐treated monkeys were at control levels and decreased in the lateral rostral caudate and caudal putamen when compared with those ofL‐DOPA‐treated and saline‐treated MPTP monkeys respectively. No change was measured in the caudal medial putamen and caudate nucleus. A2ARs labeled by autoradiography with [3H]SCH‐58261 had lower level in theL‐DOPA + CI‐1041‐treated MPTP monkeys compared with saline‐ orL‐DOPA‐treated MPTP and control monkeys in the rostral lateral and medial caudate and the putamen. No effect of lesion orL‐DOPA treatment was measured on [3H]SCH‐58261‐specific binding. These findings suggest that blockade of NMDA receptors could prevent the development of dyskinesias by altering A2ARs. Synapse 60:239–250, 2006. © 2006 Wiley‐Liss, Inc.
FACTORS INFLUENCING PREMATURE INDUCTION OF UDP-GLUCURONYLTRANSFERASE ACTIVITY IN CULTURED CHICK EMBRYO LIVER CELLS
Authors: Skea Brian R. , Nemeth Andrew M. 
Published: May 2006

Very young (5-day-old) chick embryo livers during organ culture on rafts over a chemically defined nutrient medium precociously develop, from zero, adult levels of UDP-glucuronyltransferase activity. Induction of enzyme does not require DNA synthesis or mitosis, or exposure to hormones, serum, or tissue extracts. Thus, this functional differentiation of embryo liver is apparently not dependent on cell proliferation or on extrinsic substances other than simple nutrients.
UDP-glucuronyltransferase activity develops rapidly also in embryo liver cells cultured as monolayers or aggregates; specific activity of enzyme on a protein basis increases at the same rate in cells undergoing widely different rates of cell division, and net protein synthesis.

These findings suggest that precocious development of UDP-glucuronyltransferase activity in chick embryo liver is due, not to incidents of culture, but to removal from the embryonic environment. Supporting this, chick embryo liver grafted to the chorioallantoic membrane does not develop UDP-glucuronyltransferase activity until subsequently transferred to an
in vitro
cell culture system.
Dopamine as a Synaptic Transmitter and Modulator in Sympathetic Ganglia: A Different Mode of Synaptic Action
Authors: Libet Benjamin , Tosaka Tsuneo 
Published: May 2006

An analysis of the role of adrenergic transmission in mediating the hyperpolarizing, slow inhibitory postsynaptic potential has revealed that dopamine is apparently the specific synaptic transmitter for this response. An additional action of dopamine was discovered, namely the selective facilitation of another synaptic response, the slow excitatory postsynaptic potential. (This potential is a depolarizing response to the muscarinic action of acetylcholine.) This second, modulatory, role of dopamine has characteristics strikingly different from other known modes of synaptic action. After a brief initial action by dopamine, the facilitation of the slow excitatory postsynaptic potential response can persist for hours and is unaffected by a delayed blockade of the postsynaptic receptors for dopamine. This suggests that the modulation consists of a long-lasting metabolic and/or structural change induced in the postsynaptic neuron by dopamine.
These conclusions are based on the demonstrated actions of dopamine and other catecholamines, as well as on effects (on dopamine actions and on slow postsynaptic potentials of alpha-adrenergic blockers, of blockade, of dopamine oxidase, of depletion of ganglionic catecholamine by muscarinic excitation, and of a selective re-uptake of dopamine after such depletion.
Current Induced in a Plasma by a Penetrating Electron Beam
Authors: Cox James L. , Thomas L. H. 
Published: May 2006

The passage of a single pulse of relativistic electrons through a plasma is considered, and the total current in the axial direction it induces in the plasma is calculated. This calculation is valid for an injected beam current density that has arbitrary functional dependence on the radial and azimuthal coordinates. For the special case of a beam current density that is uniform in the radial direction out to the beam radius a, these results agree with results of others published previously.
This calculation is simple because the equation for the variation with time of the plasma charge density at any point, independent of what happens at other points, is only slightly more complicated than the familiar equation for an ohmic conduction.
The Reaction of Glucagon with Its Receptor: Evidence for Discrete Regions of Activity and Binding in the Glucagon Molecule
Authors: Rodbell Martin , Birnbaumer Lutz , Pohl Stephen L. , Sundby F. 
Published: May 2006

Des-histidine-glucagon (DH-glucagon, glucagon
2-29
) does not activate the glucagon-sensitive adenylate cyclase system present in either liver plasma membranes or in fat-cell “ghosts”, but inhibits the response of these systems to submaximal concentrations of glucagon. DH-glucagon also inhibits, competitively, the binding of [
125
I]glucagon to its receptor in liver plasma membranes. Amino-terminal fragments of glucagon (glucagon
1-21
, glucagon
1-23
) and carboxy-terminal fragments (glucagon
20-29
, glucagon
22-29
) failed to activate adenylate cyclase, to inhibit the response of the enzyme to glucagon, or to compete with labeled glucagon at its receptor.

It is concluded that the amino-terminal histidine residue of glucagon is essential for biological activity and that a hydrophobic near-carboxy-terminal region (residues 22-27) is essential for binding of glucagon to its receptor. Amino-terminal histidine may also contribute to the binding of glucagon, since the apparent affinity of DH-glucagon for the receptor is only about one-sixth that of glucagon. Thus, essentially the entire molecule of glucagon must be considered to be the biologically active species.
Because, as shown elsewhere, the binding of glucagon to its receptor shows characteristics of hydrophobic bonding, and because certain detergents induce conformational changes in the carboxy-terminal binding region of glucagon, the binding is probably of a lipophilic type.
Selective Inhibition of Growth of Transformed Cells by Protease Inhibitors
Authors: Schnebli Hans Peter , Burger Max M. 
Published: May 2006

Five protease inhibitors with different modes of action were found to reduce the growth of transformed mouse (Py3T3, SV3T3, and 3T12) and hamster (PyBHK) cells. Some of these inhibitors caused the transformed cells to cease growth at saturation densities characteristic for nontransformed cells.
The protease inhibitors were strikingly selective with regard to the transformed cells; they had essentially no effect on the growth of the nontransformed cells. From this result, it is concluded that the inhibitors block a protease-like activity that is required for the unrestrained growth of transformed cells.
The inhibitors exerted their effect directly on the cells; they did not affect growth by interacting with serum components of the medium.
Identification of the Synthesis of Guanosine Tetraphosphate (MS I) as Insertion of a Pyrophosphoryl Group into the 3′-Position in Guanosine 5′-Diphosphate
Authors: Sy Jose , Lipmann Fritz 
Published: May 2006

The phosphate transfer system of Haseltine
et al.
, consisting of a ribosomal wash obtained from a stringent strain of
Escherichia coli
, washed ribosomes, GTP, and ATP, was used to prepare large quantities of guanosine tetra- and pentaphosphates, the magic spot compounds MS I and MS II of Cashel and Gallant. In our hands, the Haseltine
et al.
system yielded predominantly guanosine tetraphosphate, ppGpp. This system was used exclusively in the described experiments, with ATP labeled with
32
P in the β- and γ-positions as donor. The β-label was found to produce a
ppG

p

and the γ-label a
ppGp

.

Furthermore, [
3
H]GDP + [γ-
32
P]ATP yielded ppGpp in a
3
H:
32
P ratio of 1:1. The results indicate a transfer of the terminal pyrophosphoryl group of ATP as a unit.

The position of the transferred pyrophosphoryl was assayed for by preparation of
pG

from
ppG

p

with Zn
++
-activated inorganic pyrophosphatase from yeast. The

pG

was then assayed with 3′-nucleotidase, which liberated practically all the labeled phosphate. This result indicate that the phosphate transfer from ATP to GDP yields guanosine 5′-diphosphate-3′-diphosphate.
Mitogenic Properties of a Calcium Ionophore, A23187
Authors: Luckasen John R. , White James G. , Kersey John H. 
Published: May 2006

A23187 is a carboxylic antibiotic that selectively transfers calcium, magnesium, and other divalent cations across biologic membranes. This ionophore was found to produce morphologic blast transformation, DNA synthesis, and mitosis in human lymphocytes. Several hours of ionophore-cell contact were necessary to produce optimal mitogenesis. The effects were highly dependent on the presence of extracellular calcium and much less dependent on extracellular magnesium. Lanthanum chloride prevented the development of the observed ionophore effects.
Results are consistent with the hypothesis that under physiologic conditions the interaction of antigens or mitogens with specific receptors at the lymphocyte membrane initiates events that alter calcium fluxes and result in increased cytoplasmic calcium. Increased cytoplasmic calcium is postulated to play a central role in the generation of surface-to-nuclear signals that initiate the process of DNA synthesis and cell division.
The Presence of Unique DNA Sequences after Viral Induction of Leukemia in Mice
Authors: Sweet R. W. , Goodman N. C. , Cho J.-R. , Ruprecht R. M. , Redfield R. R. , Spiegelman S. 
Published: May 2006

From previous studies, lymphocyte DNA from human leukemias and DNA from involved tissues of patients with Hodgkin's disease or Burkitt's lymphoma contain sequences that are absent from their normal counterparts. These sequences are related to those found in particulate elements associated with these neoplasias and possessing biochemical properties characteristic of RNA tumor viruses. Similar observations have been made of unique sequences related to those of the feline virus RD-114 and found in spontaneous mastocytomas in cats. Here we extend these results to the classical murine model of virus-induced leukemias.
Splenic DNA from BALB/c mice with leukemia induced by Rauscher leukemia virus (RLV) possess some RLV-related sequences that do not exist in normal BALB/c DNA. Furthermore, these leukemia-specific sequences were absent in all other mouse strains examined, including AKR, a strain with a high incidence of spontaneous leukemia.
The DNA of all noninfected mouse strains possesses considerable homology with the RLV genome. Temperature denaturation studies indicate, however, that although the RLV-related sequences found in all normal mice are similar to each other, they are not exactly homologous with RLV sequences.
We conclude that RLV-induced leukemia in BALB/c results in the insertion of RLV sequences into cellular DNA that itself possesses only partial homology with the RLV genome.
Rates of evolution in seed plants: Net increase in diversity of chromosome numbers and species numbers through time
Authors: Levin D. A. , Wilson A. C. 
Published: May 2006

An approach was made to the problem of estimating rates of chromosomal evolution in plants. This was done by considering variability in chromosome number within genera whose ages are known approximately from fossil and biogeographic evidence. The relative increases in chromosome number diversity per lineage per unit time were as follows: herbaceous angiosperms, 100; woody angiosperms, 14; conifers, 2; and cycads, 0. Rates of increase in species diversity were estimated in an analogous way. These rates were strongly correlated with the karyotypic rates.
These evolutionary rate differences between major groups of seed plants are largely explicable in terms of the breeding structures of populations. Herbs usually have small to moderate effective population sizes, and relatively high dispersability. By contrast, woody angiosperms and gymnosperms are usually obligate outbreeders with large effective population sizes and low dispersability. Thus the probability of fixing and dispersing new karyotypes or novel character ensembles is higher in herbs than in other seed plants.
Local control of neurite development by nerve growth factor
Authors: Campenot Robert B. 
Published: May 2006

A three-chamber culture system was devised in which neurites growing from small clusters of somas of sympathetic neurons penetrated a virtually fluid-impermeable barrier; thus the local fluid environment of the distal portions of the neurites could be controlled independently of the local fluid environment of the somas and proximal portions of the neurites. Neurites regularly penetrated the barriers if a high concentration of nerve growth factor was present on both sides, but never penetrated into chambers to which no nerve growth factor had been added.
After neurites crossed the barrier, local removal of nerve growth factor from the distal portions of the neurites caused the growth of these portions to stop, and they eventually appeared to degenerate even though nerve growth factor was continuously present in the chamber that contained their somas and proximal portions. In contrast, local nerve growth factor was not required at the somas and proximal portions of the neurites; many neurons survived its withdrawal provided their somas were associated with neurite bundles that crossed into a chamber containing nerve growth factor.
These results show that the growth, and probably the survival, of neurites depends upon nerve growth factor in their local environment, regardless of the nerve growth factor concentrations to which other portions of the neuron are exposed. This is entirely consistent with the notion that nerve growth factor released by sympathetic target tissues promotes the establishment and maintenance of appropriate neuron-target connections during development.
Molecular field theory of reversible unfolding of biopolymers
Authors: Cerf Roger 
Published: May 2006

A simple and general model of reversible conformational changes in biopolymers that lends itself to accounting for cooperativity without resort to a detailed description of the elementary steps is presented. It is suggested that the model permits the description of transitions in specific instances in which long-range effects are present and no simplifying feature allows for a more detailed theory in a straightforward way. The proposed phenomenological approach is based on the concept of molecular field which led to the first theory of ferromagnetism. Equations are given for the temperature dependence of optical properties and of the specific heat, from which the cooperativity parameter introduced by the theory can be obtained when the reaction enthalpy of the elementary step or the number of concerted elements is known. In the limit of a strong molecular field, heterogeneity in composition of a melting sequence does not affect the sharpness of the corresponding transition. Accounting for long-range effects allows for all-or-none transitions that are sharper than those derived from the two-state model.
The feasibility of applying the molecular field concept is illustrated by comparing the results for poly(A)·2 poly(U) triple helices (which exhibit hysteresis) and those for poly(A)·poly(U) double helices (which separate reversibly).

Tertiary structure is considered, among the sources of cooperativity that possibly may be represented in terms of a molecular field. On the basis of recent results for tRNA
1
val
, it is suggested that the proposed approach may be applicable, in particular, to transfer ribonucleic acids.
TRIAL OF TRANSNASAL ESOPHAGOGASTRODUODENOSCOPY
Authors: Abe Kiminori , Miyaoka Masaaki 
Published: May 2006

Background:  Esophagogastroduodenoscopy (EGD) is conventionally performed transorally, although this is often a rather unpleasant experience for the patient. In the present study, we examined the merits and demerits of transnasal EGD.Materials and Methods:  We used two types of small‐diameter endoscope, produced by Olympus Co. and Fujinon Toshiba ES Systems Co., Ltd.Results:  Transnasal EGD was performed successfully in 98.8% (955/967) of patients examined. When questioned about premedication and the degree of discomfort, the great majority of patients stated that transnasal EGD was more comfortable than a transoral procedure. The incidences of nausea and vomiting were low at 8.6% (82/955) and 0.8% (8/955), respectively. Other identified adverse reactions were nasal pain in 42.9% (415/967) of patients, and epistaxis in 1.1% (11/967). The average time taken for transnasal EGD was 8.2 ± 0.7 min, approximately 1 min longer than for the transoral method.Conclusion:  Transnasal EGD is less stressful to patients than transoral EGD, and is a feasible and safe alternative.