Virulence-associated characteristics and phage lysogenicity of two morphologically distinct colonies of Vibrio cholerae O139 serogroup

Abstract The presence of a temperate phage was demonstrated in a strain of Vibrio cholerae O139 isolated from a patient. Spontaneous variants with translucent colonies had lost this phage. The loss of the phage was associated with increased hydrophobicity, indicating the loss of the capsule. These clones were sensitive to serum bactericidal activity, showed decreased expression of such presumed virulence factors as proteases, motility and mannose-sensitive pili. Furthermore, excision of the phage made the strain dependent on purines for growth.     

Modulation of antigen presentation and peptide-MHC-specific, LFA-1-dependent T cell-macrophage adhesion

Incubation of peritoneal macrophages in vitro before fixation increased their ability to present exogenous peptides to 3A9 T hybridoma cells. The enhanced level of presentation correlated with a greatly increased, peptide-specific adhesion of 3A9 cells to the macrophages, whereas peptide-independent adhesion was minimal and essentially unaltered. 3A9 cells exhibited rapid peptide-specific adhesion (plateau by 5 to 10 min) and deadhesion (complete reversal by 5 min). Peptide-specific adhesion was blocked by anti-I-Ak and anti-LFA-1. Interaction of T cell receptors and CD-4 with peptide-I-Ak complexes appeared to provide little direct contribution to the avidity of T cell-macrophage adhesion, but activated a LFA-1-mediated adhesion mechanism. In addition, anti-T cell receptor, anti-CD3, and anti-CD4 antibodies themselves activated LFA-1-dependent adhesion in the absence of peptide. Unlike the peptide-induced adhesion, this adhesion was similar for macrophages whether or not they were incubated in vitro before fixation. We conclude that the different macrophage populations supported LFA-1-mediated adhesion equally. Therefore, the enhancement of T cell stimulation observed after in vitro incubation of macrophages was due to increased peptide presentation and consequently increased triggering of LFA-1-mediated adhesion. Mechanisms may exist to regulate the effectiveness with which peptide-class II MHC complexes are displayed for T cell recognition.     

Plasma processing of spent nuclear fuel by two-frequency ion cyclotron resonance heating

A previously developed method for analyzing the plasma processing of spent nuclear fuel is generalized to a plasma containing multicharged fuel ions. In such a plasma, ion cyclotron resonance heating of nuclear ash ions should be carried out in two monochromatic RF fields of different frequencies, provided that the fraction of ξ multicharged ions is small, ξ ≤ 0.1, a condition that substantially restricts the productivity of systems for processing spent nuclear fuel. Ways of overcoming this difficulty are discussed.     

Concerning Measurements of the Self-Diffusion Coefficient of Water Molecules and Time of Proton Spin-Lattice Relaxation in Plant Tissues

Measurements of the coefficient of water molecules self-diffusion (D) and the time of spin-lattice relaxation (T ₁) in prosenchyme (elongated) plant cells, whose length significantly exceeding their transverse size, show that the orientation of plant tissues in the H ₀field significantly affects the measured parameters. We conclude that this effect should be taken into account in experiments on the measurement of self-diffusion coefficients and time of proton spin-lattice relaxation in plant tissues containing prosenchyme cells.     

Investigation of assisted fertilization and biology of reproduction by sperm microinjection

Recent success in assisted fertilization mainly depended on the development of sperm microinjection methods: intracytoplasmic sperm injection and subzonal insemination. Some basic mechanisms that under-lie fertilization were revealed by using intracytoplasmic sperm injection. In respect to this, problems of fertility, oocyte activation, formation of pronuclei and practical aspects of intracytoplasmic sperm injection are discussed.     

Vers une approche physiopathologique des troubles de l’éjaculation

Seminal emission and sperm expulsion are under the control of both the sympathetic and parasympathetic outflows and also of the somatic innervation conveyed by the pudendal nerve. The 2 phases of ejaculation are reflexive with the reflexes handled at the thoraco-lumbar and sacral levels of the spinal cord. Such a spinal organization remains widely unknown. The role of various peripheral neurotransmitters has been evidenced including norepinephrine and acetylcholine and also peptidergic, purinergic i.e. ATP and nitric oxide. Stimulation of the seminal tract afferents play a crucial in the onset of ejaculatory mechanisms. Except for the dorsal nerve of the penis, there is a lack of information concerning these afferents. Several supraspinal centers i.e. hypothalamus, medial amygdala, pons and nucleus paragigantocellularis exert descending and ascending inhibitory and excitatory influences on spinal nuclei controlling emission and expulsion of sperm. Central neurotransmission responsible for this supraspinal control could involve serotonin, oxytocin and norepinephrine. In the light of the available anatomical and neurophysiological data, pathophysiological aspects of ejaculatory disorders are futher discussed. Premature ejaculation could be related to a periheral and central hypersentivity. Most of the other ejaculation abnormalities are likely mainly related to an impairment of the central mechanisms.