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PubMedDate not supplied

Immediate effects of cerebral ischemia: evolution and resolution of neurological deficits after experimental occlusion of one middle cerebral artery in conscious cats.

Acute occlusion of the left middle cerebral artery (MCA) was accomplished without anesthesia and inside an intact cranium containing cerebrospinal fluid (CSF) in ten cats five to nine days after implantation of an occlusive device through the orbit. Immediate neurological deficits included forced ambuxlation, circling, and tonic deviation of the head and neck toward the side of the occluded artery; weakness of the opposite limbs; and an apathetic or akinetic state. Two cats died within 24 hours. The other eight cats improved but secondary deficits developed in two, causing death. In two of the remaining six cats no deficits were apparent seven days later. The cerbral infarcts regularly involved the basal ganglia, internal capsule, and cortical regions, and were larger and less variable than those produced by MCA occlusion through and open optic foramen or craniectomy with cranial decompression by drainage of CSF. This model of acute focal cerebral ischemia may be of value for studies of physiological and biochemical factors uninfluenced by sedatives, anesthesia, or recent surgical procedures.

Animals↗
PubMed1997

Novel and dynamic evolution of equine infectious anemia virus genomic quasispecies associated with sequential disease cycles in an experimentally infected pony.

We have investigated the genetic evolution of three functionally distinct regions of the equine infectious anemia virus (EIAV) genome (env, rev, and long terminal repeat) during recurring febrile episodes in a pony experimentally infected with a well-characterized reference biological clone designated EIAV(PV). Viral populations present in the plasma of an EIAV(PV)-infected pony during sequential febrile episodes (18, 34, 80, 106, and 337 days postinfection) were amplified from viral RNA, analyzed, and compared to the inoculated strain. The comparison of the viral quasispecies showed that the inoculated EIAV(PV) quasispecies were all represented during the first febrile episode, but entirely replaced at the time of the second febrile episode, and that new predominant quasispecies were associated with each subsequent cycle of disease. One of the more surprising results was the in vivo generation of large deletion (up to 15 amino acids) in the principal neutralizing domain (PND) of gp90 during the third febrile episode. This deletion did not alter the competence for in vitro replication as shown by the analysis of a env chimeric clone with a partially deleted PND and did not altered the fitness of the virus in vivo, since this partially deleted envelope became the major population during the fourth febrile episode. Finally, we showed that the amino acid mutations were not randomly distributed but delineated eight variables regions, V1 to V8, with V3 containing the PND region. These studies provide the first detailed description of the evolution of EIAV genomic quasispecies during persistent infection and reveal new insights into the genetics and potential mechanisms of lentivirus genomic variation.

Amino Acid Sequence↗
PubMedDate not supplied

The influence of homologous pulmonary proteins on the lung tissue reactivity: an experimental analysis.

The influence of homologous pulmonary proteins on the lung tissue reactivity was experimentally and immunomorphologically analysed in rabbits: a. in the development of specific sensitized substrate; b. by the challenge of hypersensitivity reactions: and c. by the evaluation of the development of an experimental lung tuberculosis at the level of the sensitized lung. Morphometrical methods were used. The immunomorphological analysis pointed out the importance of the increase of pyroninophilic and plasma cells and of eosinocytes in the lung tissue sensitized to homologous proteins included in the complete Freund adjuvant, the specificity and peculiarities (frequency of plasmocytosis and necrosis) of hypersensitivity reactions intratracheally and intravenously challenged with the homologous pulmonary proteins at the level of the sensitized lung, as well as the severe evolution of the experimental lung tuberculosis by comparison with that developing in a lung substrate sensitized without homologous pulmonary proteins or unsensitized. These results provided data for the influence exerted on the lung substrate by the pulmonary proteins which are released during the evolution of lugn processes and could act as autoantigens in the framework of an autoaggressive pathogenic component of chronic diseases.

Anaphylaxis↗
PubMed2006

Rotranslational state-to-state rates and spectral representation of inelastic collisions in low-temperature molecular hydrogen.

Inelastic collisions in natural H2 are studied from the experimental and theoretical points of view between 10 and 140 K. Rotational populations and number densities measured by Raman spectroscopy along supersonic expansions of H2 provide the link between experimental and theoretical rotranslational state-to-state rate coefficients of H2 in the vibrational ground state. These rates are calculated in the close-scattering approach with the MOLSCAT code employing a recent ab initio H2-H2 potential. The calculated rates are assessed by means of a master equation describing the time evolution of the experimental rotational populations. The feasibility for obtaining the rates on the sole basis of the experiment is discussed. The dominant processes j(1)j(2)-->j'(1)j'(2) in the investigated thermal range are found to be 21-->01 >30-->12 >31-->11, proving the importance of double processes such as 30-->12. Good agreement is found between theory and experiment, as well as with earlier ultrasonic measurements of relaxation times. A spectral representation is proposed in order to visualize quantitatively the collisional contributions in any nonequilibrium time evolving process.

Journal Article↗
PubMed2005

Evolution of topological order in Xe films on a quasicrystal surface.

We report results of the first computer simulation studies of a physically adsorbed gas on a quasicrystalline surface Xe on decagonal Al-Ni-Co. The grand canonical Monte Carlo method is employed, using a semiempirical gas-surface interaction, based on conventional combining rules, and the usual Lennard-Jones Xe-Xe interaction. The resulting adsorption isotherms and calculated structures are consistent with the results of LEED experimental data. The evolution of the bulk film begins in the second layer, while the low coverage behavior is epitaxial. This transition from epitaxial fivefold to bulklike sixfold ordering is temperature dependent, occurring earlier (at lower coverage) for the higher temperatures.

Journal Article↗
PubMed2000

An experimental test of the thermoregulatory hypothesis for the evolution of endothermy.

The thermoregulatory hypothesis proposes that endothermy in mammals and birds evolved as a thermoregulatory mechanism per se and that natural selection operated directly to increase body temperature and thermal stability through increments in resting metabolic rate. We experimentally tested this hypothesis by measuring the thermoregulatory consequences of increased metabolic rate in resting lizards (Varanus exanthematicus). A large metabolic increment was induced by feeding the animals and consequent changes in metabolic rate and body temperature were monitored. Although metabolic rate tripled at 32 degrees C and quadrupled at 35 degrees C, body temperature rose only about 0.5 degrees C. The rate of decline of body temperature in a colder environment did not decrease as metabolic rate increased. Thus, increasing the visceral metabolic rate of this ectothermic lizard established neither consequential endothermy nor homeothermy. These results are inconsistent with a thermoregulatory explanation for the evolution of endothermy.

Air↗