TFAR19, a novel apoptosis-related gene cloned from human leukemia cell line TF-1, could enhance apoptosis of some tumor cells induced by growth factor withdrawal

The mitochondrial DNA (mtDNA) in animals is generally a circular molecule of approximately 15 kb, but there are many exceptions such as linear molecules and larger ones. RFLP studies indicated that the mtDNA in the terrestrial isopod Armadillidium vulgare varied from 20 to 42 kb. This variation depended on the restriction enzyme used, and on the restriction profile generated by a given enzyme. The DNA fragments had characteristic electrophoretic behaviors. Digestions with two endonucleases always generated fewer fragments than expected; denaturation of restriction profiles reduced the size of two bands by half; densitometry indicated that a number of small fragments were present in stoichiometry, which has approximately twice the expected concentration. Finally, hybridization to a 550-bp 16S rDNA probe often revealed two copies of this gene. These results cannot be due to the genetic rearrangements generally invoked to explain large mtDNA. We propose that the large A. vulgare mtDNA is produced by the tripling of a 14-kb monomer with a singular rearrangement: one monomer is linear and the other two form a circular dimer. Densitometry suggested that these two molecular structures were present in different proportions within a single individual. The absence of mutations within the dimers also suggests that replication occurs during the monomer phase.     

Analysis of compaction behaviour of wet granulated aluminium alloy powder

Abstract

The compaction behaviours of wet granulated aluminium powder were examined by uniaxial die compaction, and their effect on rearrangement and plastic deformation was analysed by using the Cooper–Eaton equation. Based on the calculation results and structure/morphology of the granulated powder, a new compaction model for granulated powder, which consists of three compaction mechanisms (macrorearrangement, microrearrangement, and plastic deformation), and a modified equation has been proposed in this study. A macrorearrangement indicates it to be a dominant factor on the compaction behaviour of granulated powder and the modified equation is sufficient to analyse the compaction behaviour.     

Hepatitis B immunization: a potential incentive to HIV vaccine trial participation in Thailand?

OBJECTIVE: To investigate the incidence, anatomical correlates, and clinical features of imitation and utilisation behaviour, which are thought by Lhermitte and coworkers to represent a reliable and frequent index of frontal lobe disease. METHODS: 78 patients with hemispheric local lesions were tested in two separate sessions, in which their reactions to a series of gestures performed by the examiner and to the presentation of a set of objects were recorded. The patients were stratified into a frontal (n = 52) and a non-frontal group (n = 26) on the basis of their CT data. RESULTS AND CONCLUSIONS: Imitation behaviour was present in 39% of the frontal patients and was mainly associated with medial and lateral lesions, at odds with the claim of Lhermitte et al that it is a constant accompaniment of lower, mediobasal lesions. In the non-frontal group it was found in three patients, all with damage to the deep nuclei region. Utilisation behaviour was a much rarer phenomenon, present in only two patients, both of whom had frontal damage. Neither imitation behaviour nor utilisation behaviour were found in patients with retrorolandic cortical lesions.     

Inactivation of the p53 tumor suppressor gene via a novel Alu rearrangement

Inactivation of the p53 tumor suppressor gene is a common finding in human cancer. In most cases, inactivation is due to a point mutation in the gene, but rearrangement of the p53 gene is sometimes observed. We analyzed the inactivation of p53 in the human pancreas cancer cell line Hs766T, which harbors a structural alteration in the p53 gene. This inactivation was found to be the result of a complex deletion/insertion event involving at least two different Alu elements. The rearrangement eliminated exons 2-4 from the p53 gene, whereas a 175-bp Alu fragment was inserted between the breakpoints of the deletion. DNA sequence analysis of this Alu fragment revealed that it is identical to an Alu element in intron 1 of the p53 gene. This is the first report of p53 inactivation due to a rearrangement involving Alu elements. This type of inactivation may go unnoticed when only traditional methods to detect p53 alterations are used.     

Pseudoelastic and anelastic effects due to the motion of twin boundaries in copper-based alloys

Copper alloys, e.g. with a few at.% of Ge, are known to deform by slip and twinning when subjected to a tensile test at room temperature. Such alloys exhibit a large hysteresis loop or pseudoelasticity in a loading-unloading cycle, which is believed to be due to reversible motion of twin boundaries. The mobility and the annealing behaviour of twinning dislocations in several copper alloys with Ge, Si or Al have been studied by low-frequency internal friction measurements, electrical resistivity measurements and electron microscopy. Deformed samples show a characteristic anelastic effect; internal friction increases linearly with temperature in the range from 80 to 280 K and falls down rapidly above room temperature. The magnitude of the anelastic effect depends on the solute concentration and on the degree of deformation similarly to that of the pseudoelastic effect. The internal friction is tentatively explained as arising either from l ocal motion of twinning dislocations or from rearrangement of metastable stacking sequences.     

Telomere variation in Xenopus laevis

Eukaryotic telomeres are variable at several levels, from the length of the simple sequence telomeric repeat tract in different cell types to the presence or number of telomere-adjacent DNA sequence elements in different strains or individuals. We have investigated the sequence organization of Xenopus laevis telomeres by use of the vertebrate telomeric repeat (TTAGGG)n and blot hybridization analysis. The (TTAGGG)n-hybridizing fragments, which ranged from less than 10 to over 50 kb with frequently cutting enzymes, defined a pattern that was polymorphic between individuals. BAL 31 exonuclease treatment confirmed that these fragments were telomeric. The polymorphic fragments analyzed did not hybridize to 5S RNA sequences, which are telomeric according to in situ hybridization. When telomeric fragments from offspring (whole embryos) were compared to those from the spleens of the parents, the inheritance pattern of some bands was found to be unusual. Furthermore, in one cross, the telomeres of the embryo were shorter than the telomeres of the parents' spleen, and in another, the male's testis telomeres were shorter than those of the male's spleen. Our data are consistent with a model for chromosome behavior that involves a significant amount of DNA rearrangement at telomeres and suggest that length regulation of Xenopus telomeres is different from that observed for Mus spretus and human telomeres.     

Binocular visual surface perception

Binocular disparity, the differential angular separation between pairs of image points in the two eyes, is the well-recognized basis for binocular distance perception. Without denying disparity's role in perceiving depth, we describe two perceptual phenomena, which indicate that a wider view of binocular vision is warranted. First, we show that disparity can play a critical role in two-dimensional perception by determining whether separate image fragments should be grouped as part of a single surface or segregated as parts of separate surfaces. Second, we show that stereoscopic vision is not limited to the registration and interpretation of binocular disparity but that it relies on half-occluded points, visible to one eye and not the other, to determine the layout and transparency of surfaces. Because these half-visible points are coded by neurons carrying eye-of-origin information, we suggest that the perception of these surface properties depends on neural activity available at visual cortical area V1.     

Production of Al–Cu and Al–Cu–Si Alloys by PM Methods

Abstract

The possibilities of the production of aluminium-base copper and/or silicon alloys by conventional powder compaction and sintering methods have been studied. The effects of various lubricants, pressing, and sintering conditions on the behaviour of Al–Cu and Al–Cu–Si alloys were evaluated systematically. The role of copper and silicon additions during compaction and sintering and their advantages or disadvantages are discussed. All alloys underwent large dimensional changes (sudden swelling followed by rapid contraction) during sintering at temperatures greater than Al–Cu eutectic temperature and it is suggested that a process of particle rearrangement is largely responsible for this behaviour. The mechanical properties of the alloys were highly dependent on the sintering temperature. PM/0215     

Analysis of Dimensional Changes During Sintering of Fe—Cu

Abstract

The dimensional changes of Fe–Cu compacts during sintering are of considerable interest for the production of sintered parts. Previous investigations of the swelling and shrinkage behaviour were mostly based on dilatometric measurements and led to partially contradictory results. In the present investigation Fe and Cu powders of ideal sphericity were compacted to densities of up to 93%, sintered for different times, and then rapidly cooled. The simultaneous measurement of density and microstructural parameters permitted the quantitative distinction of the swelling mechanism of Fe–Cu compacts into four main contributions; I penetration of the melt between Fe particles and II along the grain boundaries; III diffusion of Cu into the Fe particles from the particle surface; and IV diffusion of Cu into the Fe grains from the grain boundaries. Whereas the penetration between the Fe particles is the result of pure capillary forces the penetration along grain boundaries is thought to be a special case of solution-reprecipitation.

Particle rearrangement during sintering of Fe–Cu compacts could be separated into two stages. Primary particle rearrangement, just after the melt phase occurs, leads to rapid densification of loose packed and slightly compacted specimens. In highly compacted specimens it can be neglected. The penetration of the melt along the grain boundaries leads to disintegration of the Fe particles, which enables densification by rearrangement of the individual grains of the Fe particles.     

Bipolar meiotic spindle formation without chromatin

Establishing a bipolar spindle is an early event of mitosis or meiosis. In somatic cells, the bipolarity of the spindle is predetermined by the presence of two centrosomes in prophase. Interactions between the microtubules nucleated by centrosomes and the chromosomal kinetochores enable the formation of the spindle. Non-specific chromatin is sufficient, however, to promote spindle assembly in Xenopus cell-free extracts that contain centrosomes [1,2]. The mouse oocyte represents an excellent model system in which to study the mechanism of meiotic spindle formation because of its size, transparency and slow development. These cells have no centrioles, and their multiple microtubule-organizing centers (MTOCs) are composed of foci of pericentriolar material [3,4]. The bipolarity of the meiotic spindle emerges from the reorganization of these randomly distributed MTOCs [4]. Regardless of the mechanisms involved in this reorganization, the chromosomes seem to have a major role during spindle formation in promoting microtubule polymerization and directing the appropriate rearrangement of MTOCs to form the two poles [5]. Here, we examined spindle formation in chromosome-free mouse oocyte fragments. We found that a bipolar spindle can form in vivo in the absence of any chromatin due to the establishment of interactions between microtubule asters that are progressively stabilized by an increase in the number of microtubules involved, demonstrating that spindle formation is an intrinsic property of the microtubule network.     

Interstitial telomeric repeats within the Arabidopsis thaliana genome

A highly systematic, non-cloning method of distinguishing and isolating every fragment in a class-IIS or interrupted palindrome restriction digest has been developed in our laboratory. These enzymes produce informative, non-identical cohesive ends which can be selectively modified by ligation to individual synthetic oligodeoxyribonucleotides with the corresponding complementary ends. In this way, polymerase chain reaction and sequencing primer sites and labels can be introduced specifically into a single fragment in a total genomic digest. Known and unknown fragments from genomes of the complexity of Escherichia coli can be isolated directly in sequencable form without the necessity of synthesizing unique primers. Human DNA has also been assessed in this way. Problems intrinsic to cloning (selective fragment loss, mutation and sequence rearrangement) are avoided. Systematic characterization of DNA fragments by their cohesive ends and length provides tremendous power and flexibility for analysis of any DNA molecule without specific clones, probes or libraries. We report proof of principle of this remarkable system and indicate potential applications in DNA sequence tagged site and restriction mapping, sequencing, restriction-fragment-length polymorphism analysis and DNA diagnostics.     

The effect of exercise training in cold on shivering and nonshivering thermogenesis in adult and aged C57BL/6J mice

The behaviour of plasma membrane was studied in UV-treated cells to investigate its involvement in apoptosis. It was studied in HL60 cells, in which DNA oligonucleosomic cleavage occurs, and in Molt-4 cells, which are characterised by a different fragmentation pattern. During the early stages of apoptosis, a membrane lipid rearrangement occurs, which involves phosphatidylserine translocation from the inner to the outer leaflet. This molecular alteration was investigated by annexin V-FITC binding, analysed by flow cytometry and confocal microscopy. It was correlated with transmission electron microscopy, subdiploid peak appearance and DNA fragmentation. Our data indicate that the plasma membrane represents an early apoptotic target, even if its alterations are not detectable by ultrastructural analysis, which indicates its good preservation until late apoptotic stages. In addition, the study of apoptotic cells with absent or inactivated endonuclease demonstrates the independence of this membrane mechanism from nuclear activity.     

Two-label peak-height encoded DNA sequencing by capillary gel electrophoresis: three examples

We report a modification to the peak-height encoded DNA sequencing technique of Tabor and Richardson. As in the original protocol, the sequencing reaction uses modified T7 polymerase with manganese rather than magnesium to produce very uniform incorporation of each dideoxynucleoside. To improve sequencing accuracy, two fluorescently labeled primers are employed in separate sequencing reactions. As an example, one sequencing reaction uses a FAM-labeled primer with dideoxyadenosine triphosphate and dideoxycytosine triphosphate; the concentrations of ddATP and ddCTP are adjusted to produce a 2:1 variation in the relative intensity of fragments. The second sequencing reaction uses a TAMRA labeled primer with dideoxythymidine triphosphate and dideoxyguanidine triphosphate; the concentrations of ddTTP and ddGTP are adjusted to produce a 2:1 variation in relative intensity of fragments. The pooled reaction products are separated by capillary gel electrophoresis and identified by one of three different detector systems. Use of a 2:1 peak height ratio typically produces a sequencing accuracy of 97.5% for the first 350 bases; a 3:1 peak height ratio improves accuracy to 99.5% for the first 400 bases. For these experiments, capillary electrophoresis is performed at an electric field of 200 V/cm; two to three hours are required to separate sequencing fragments up to 400 nucleotides in length.     

Particle rearrangement during powder compaction

Densification in powder compaction occurs due to the motion of particle centers toward each other, including particle rearrangement and particle deformation. The process of particle sliding and rearrangement has a critical influence on densification in practice, especially during the first stage of compaction. Analytic models and experimental measurements show that the movements of individual particles within a powder compact cause continuous tightening of the bulk packing state up to a fractional compact density of 0.92. For a mass of powder with an initial packing density of 0.64, up to a 40 pct green density increase during the first stage of densification occurs by particle rearrangement. The present study proposes a parameter, termed the particle-packing factor, that describes the packing state due to both deformation and rearrangement.     

Additive strengthening mechanisms in dispersion hardened polycrystals

Tensile data from polycrystalline samples of copper dispersion strengthened by alumina are analysed. The basis of this analysis is to look at the strain range from 0.05 to 0.20 where the stress-strain curves show a parabolic hardening behaviour and are parallel to one another. The means by which the addition of strength components from various elements of the microstructure and substructure might explain this behaviour are investigated. It is shown that a linear combination of a matrix friction stress, an Orowan bowing stress, a matrix mean stress from the particles and a combined dislocation interaction term can explain this data and also the data from some aluminium-alumina materials. The dislocation interaction term, which dominates, is comprised of terms which cover the pure matrix work hardening, the hardening due to particles and due to the grain boundaries. This term is derived by summing the dislocation density contributions from each of these three sources. The type of additivity suggested here not only gives very good agreement with the stress-strain data but it also uses and is in accord with the experimental measurements of dislocation densities made using transmission electron microscopy.     

Indirect immobilization of recombinant proteins to a solid phase using the albumin binding domain of streptococcal protein G and immobilized albumin

Gradient elution reversed-phase high-performance liquid chromatographic and capillary electrophoretic separations were optimised to separate substance P (SP) and twelve of its fragments. The methods were applied to a study of the in vivo metabolism of substance P in the rat after intrastriatal injection of the peptide (10 nmol). SP and significant amounts of its N-terminal fragments, SP(1-7) and SP(1-4), were detected but no major C-terminal fragments could be identified. At the concentration studied, the metabolism of SP was shown to follow zero order elimination kinetics with a rate of decay of 0.2 nmol/min. As we have shown that SP(1-4) and SP(1-7) can be produced in vivo in the striatum in relatively large amounts, it is conceivable that these fragments contribute to the overall pharmacological pattern of activity of the parent peptide.     

R-curve behaviour of Al2O3 ceramics

The fracture micromechanics and underlying physical processes of fracture in Al₂O₃-based ceramic specimens have been studied as a function of grain size by instrumented in situ dynamic scanning electron microscopy (SEM) using the double torsion technique. The toughness is found to increase with grain size. Crack bridging is found to extend over hundreds of grain diameters behind the crack tip, resulting in R-curve behaviour. Evidence is amassed which points to frictional energy dissipation, rather than distrubuted microcracking or crack-closure due to elastic ligaments, as the dominant contribution to toughening. The friction occurs at grains which bridge the crack faces and are pulled out as the faces separate. Restraining stresses, which constrain the bridging grains in their sockets, are believed to be the result of both grain morphology and the thermal expansion anisotropy of the material. Simple modelling indicates that only a few percent of the grains need be involved in the frictional process to account for the toughening. The conclusion is supported by hysteresis measurements.