Relationship between altered axial curvature and neural tube closure in normal and mutant (curly tail) mouse embryos

In isolated smooth muscles of the rat stomach, the properties of electrical responses of the membrane elicited by transmural nerve stimulation were studied. The smooth muscle membranes were quiescent in the fundus and spontaneously active with slow waves and often action potentials superimposed on top of the slow wave in the antrum and pylorus. The maximum membrane potentials were larger in the antrum (-50 to -55 mV) than in the fundus (-40 to -45 mV). Transmural nerve stimulation elicited an excitatory junction potential (e.j.p.) which was followed by an inhibitory junction potential (i.j.p.) in the fundus, and an i.j.p. alone in the antrum. The e.j.p. was inhibited by atropine, indicating that this potential was cholinergic in nature. The amplitude of the e.j.p. was increased by apamin or nitroarginine, and the latter was more potent than the former. The i.j.p. was inhibited by apamin or nitroarginine, and was resistant to adrenergic and cholinergic blocking agents, and therefore this potential was non-adrenergic non-cholinergic (NANC) in nature. The inhibitory actions of nitroarginine on the i.j.p. were antagonized by L-arginine, suggesting the involvement of nitric oxide (NO) in this junctional transmission. The results indicate that smooth muscles of the rat stomach receive cholinergic excitatory and NANC inhibitory nerves, and that endogenous NO may either be partly responsible for the generation of the i.j.p. or may modulate the junctional transmissions.     

Pathogenesis of preeclampsia: a comprehensive model

PROBLEM: Therapy of children with relapsed acute lymphoblastic leukemia (ALL) not achieving a second remission (CR2) after an initial reinduction attempt is problematic. METHODS: 52 children with ALL in first relapse received high-dose cytosine arabinoside and L-asparaginase (HDAraC/L-Asp) after failed attempts to achieve CR2. AraC was given at a dose of 3 gm/m2 q12 h x 4 on days 0-1 and 7-8. L-asparaginase was given IM 6,000 IU/m2 3 hours after completion of each 2-day cycle of AraC. RESULTS: Of the 42 surviving to day 28, 22 (42% of all patients) achieved CR2. Ten died before day 28 (19%); four from leukemia and six from infections or toxicity (12% regimen-related mortality), There were 17 bacterial infections (three fatal), 17 invasive fungal infections (12 fatal), one fatal adenoviral infection, and one-non-fatal Pneumocystis pneumonia. One patient was surviving when lost to follow-up at four months and one patient survives over 5 years after transplant. Sixteen of the 22 patients who entered CR2 subsequently relapsed, five died of non-leukemic causes, and one was lost to follow-up. The median duration of second remission was 3 months (range 0.7 to 19 months). CONCLUSIONS: HDAraC/L-Asp rescue reinduction for relapsed childhood ALL achieves CR2 in approximately 40% of patients who fail reinduction, but remissions are short for most patients and maintenance of CR2 remains unsatisfactory.     

Vortex Matter in the Presence of Magnetic Pinning Centra

Within the non-linear Ginzburg-Landau (GL) theory, we investigate the vortex structure of a thin type II superconductor with a ferromagnetic dot on top of it. Spontaneous creation of vortex-antivortex pairs as well as specific arrangements of vortices are found. We show that the equilibrium vortex phase diagram depends on the size of the magnetic dot and its magnetization, and we discuss the shell structure of the multivortex states with magic numbers which are size and magnetization dependent.     

Mechanism of carbon–nitrogen bond scission in the presence of H2S on Pt Supported catalysts

The reactivity of a series of amines with various structures and different numbers of hydrogen atoms on the carbon atoms in the and position was used to evidence the C–N bond scission mechanism in the presence of H₂S on Pt based catalysts (deposited on alumina, zirconia and silica–alumina) and compare it with the mechanism on a NiMoP on alumina sulfide catalyst. The effect of the H₂S partial pressure was also checked. Catalytic activities (amine overall conversion, C₅ hydrocarbon formation, and amine disproportionation) deeply depend on the structure of the N-containing molecule. Tert-pentylamine is the most reactive molecule for sulfide catalysts whereas, in the case of n-pentylamine, Pt on zirconia was found to be the most efficient for C–N bond breaking. Such properties cannot be related to the acidic properties of the support but to a unique support–metal interaction, since alumina or silica–alumina supported platinum catalysts do not present this behaviour.     

Theoretical study of InAs/GaAs quantum dots grown on [11k] substrates in the presence of a magnetic field

Eight-band k.p theory including strain and piezoelectric effects are employed to calculate the strain distribution and electron and hole energy levels of InAs/GaAs quantum dots grown on [11k] substrates in the presence of an external magnetic field. Height of the dot determines how the increasing of k influences isotropic part of the strain tensor while biaxial part of the strain tensor is always reduced with increasing k. Because of the reduced symmetry of high index surfaces, influence of piezoelectric effect on the electronic structure becomes more dominant with increasing k. Electron energy levels are influenced by the isotropic part of the strain compared to the hole energy levels, where strong heavy hole–light-hole mixing is observed. For the dots grown on the [11k] surfaces magnetic field has smaller influence on the electron and hole energy levels as compared to the referent case.     

Effect of intraventricular administration of isoprenaline on urinary function in the goat

Normal hematopoetic cells require the presence of a protein (MGI) in the appropriate conditioned medium (CM) for cell viability and growth and for differentiation to mature macrophages and granulocytes. Clones of myeloid leukemic cells have been established in culture (D+ clones) which require CM with this protein for differentiation, but not for cell viability and growth. It has been shown that these leukemic cells can be induced by CM to again require, like normal cells, the presence of CM for cell viability and growth. Induction of this requirement, which will be referred to as RVG, occurred before the D+ cells differentiated to mature granulocytes. Clones of myeloid leukemic cells (D- clones) that could not be induced to differentiate to mature cells, did not show the induction of RVG. The steroid hormones prednisolone and dexamethasone can induce some, but not all the changes associated with differentiation of D+ cells, Incubation with these steroids did not result in the induction of a requirement for these steroids for cell growth and viability. Studies with CM from different sources have shown, that all batches that induced RVG also induced differentiation of D+ cells and that both activities were inhibited after treating the CM with trypsin. It is suggested that the same protein (MGI) may be involved in both activities. Incubation of D+ cells with CM resulted in an increase in agglutinability by concanavalin A and this increase was maintained even in the absence of CM. This suggests, that the induction of RVG in D+ myeloid leukemic cells is associated with a change in the cell surface membrane.     

Equalization for DMT based broadband modems

Faced with fierce competition from cable operators, telephone companies are now aggressively investing in digital subscriber line technology with the objective of providing an economic broadband access alternative. However, high-bit-rate transmissions over the metallic access network is far from trivial. The subscriber loop predominantly consists of interconnection of twisted pair copper sections. This causes severe attenuation of the high-frequency components of the transmitted signal. Equalization refers to the signal processing in the transceiver to combat the effects of the dispersive channel on the transmitted signal. This article overviews equalization methods for discrete multitone modulation (DMT). The interference structure created by a non-ideally equalized channel is analyzed. Time modulation as well as frequency domain equalization methods are addressed