Developmental toxicity evaluation of ethylene glycol by gavage in New Zealand white rabbits

Artificially inseminated New Zealand white (NZW) rabbits were administered ethylene glycol (EG) by gavage on Gestational Days (GD) 6 through 19 at doses of 0, 100, 500, 1000, or 2000 mg/kg/day, with 23-24 inseminated animals per group. Clinical signs were recorded and water consumption was measured daily; does were weighed on GD 0, 6-19, 25, and 30. At necropsy (GD 30), maternal liver, kidney, and gravid uterine weights were recorded. Histopathologic examination was performed on kidneys from 10 does/dose and for all unscheduled deaths. Ovarian corpora lutea were counted and uterine implantation sites (total sites, resorptions, dead and live fetuses) were recorded. All live fetuses were weighed, sexed, and examined for external, visceral, and skeletal malformations and variations. EG resulted in profound maternal toxicity at 2000 mg/kg/day (42% mortality; three early deliveries and one spontaneous abortion) associated with renal pathology and unaccompanied by any other indicators of maternal toxicity. Renal lesions at 2000 mg/kg/day involved the cortical renal tubules and included intraluminal oxalate crystals, epithelial necrosis, and tubular dilatation and degeneration. No dose-related maternal toxicity occurred at 100-1000 mg/kg/day. There was no indication of developmental toxicity at any dose tested, including no effects on pre- or postimplantation loss, number of fetuses, fetal body weight, or sex ratio (% male fetuses) per litter, and no evidence of teratogenicity. The "no observable adverse effect level" (NOAEL) for maternal toxicity was therefore 1000 mg/kg/day and the NOAEL for developmental toxicity was at least 2000 mg/kg/day in this study. The sensitivity of NZW rabbits relative to that of Sprague-Dawley rats and Swiss mice for maternal and developmental toxicity from gavage administration of EG during organogenesis can be determined for maternal toxicity: rabbits > mice > rats, and for developmental toxicity, mice > rats > rabbits.     

Inhibitory effects of recombinant manganese superoxide dismutase on influenza virus infections in mice

The oxygen free-radical scavenger recombinant human manganese superoxide dismutase (MnSOD) was studied for its effects on influenza virus infections in mice when used alone and in combination with ribavirin. Mice challenged with influenza A/NWS/33 (H1N1) virus were treated parenterally in doses of 25, 50, and 100 mg/kg of body weight per day every 8 h for 5 days beginning at 48 h post-virus exposure. An increase in mean day to death, lessened decline in arterial oxygen saturation, and reduced lung consolidation and lung virus titers occurred in the treated animals. To determine the influence of viral challenge, experiments were run in which mice were infected with a 100 or 75% lethal dose of virus and were treated intravenously once daily for 5 days beginning 96 h after virus exposure. Weak inhibition of the mortality rate was seen in mice receiving the high viral challenge, whereas significant inhibition occurred in the animals infected with the lower viral challenge, indicating that MnSOD effects are virus dose dependent. To determine if treatment with small-particle aerosol would render an antiviral effect, infected mice were treated by this route for 1 h daily for 5 days beginning 72 h after virus exposure. A dose-responsive disease inhibition was seen. An infection induced by influenza B/Hong Kong/5/72 virus in mice was mildly inhibited by intravenous MnSOD treatment as seen by increased mean day to death, lessened arterial oxygen saturation decline, and lowered lung consolidation. MnSOD was well tolerated in all experiments. A combination of MnSOD and ribavirin, each administered with small-particle aerosol, resulted in a generally mild improvement of the disease induced by the influenza A virus compared with use of either material alone.     

CD4-independent, CCR5-dependent infection of brain capillary endothelial cells by a neurovirulent simian immunodeficiency virus strain

Brain capillary endothelial cells (BCECs) are targets of CD4-independent infection by HIV-1 and simian immunodeficiency virus (SIV) strains in vitro and in vivo. Infection of BCECs may provide a portal of entry for the virus into the central nervous system and could disrupt blood-brain barrier function, contributing to the development of AIDS dementia. We found that rhesus macaque BCECs express chemokine receptors involved in HIV and SIV entry including CCR5, CCR3, CXCR4, and STRL33, but not CCR2b, GPR1, or GPR15. Infection of BCECs by the neurovirulent strain SIV/17E-Fr was completely inhibited by aminooxypentane regulation upon activation, normal T cell expression and secretion in the presence or absence of ligands, but not by eotaxin or antibodies to CD4. We found that the envelope (env) proteins from SIV/17E-Fr and several additional SIV strains mediated cell-cell fusion and virus infection with CD4-negative, CCR5-positive cells. In contrast, fusion with cells expressing the coreceptors STRL33, GPR1, and GPR15 was CD4-dependent. These results show that CCR5 can serve as a primary receptor for SIV in BCECs and suggest a possible CD4-independent mechanism for blood-brain barrier disruption and viral entry into the central nervous system.     

An essential role for ectodomain shedding in mammalian development

The ectodomains of numerous proteins are released from cells by proteolysis to yield soluble intercellular regulators. The responsible protease, tumor necrosis factor-alpha converting enzyme (TACE), has been identified only in the case when tumor necrosis factor-alpha (TNFalpha) is released. Analyses of cells lacking this metalloproteinase-disintegrin revealed an expanded role for TACE in the processing of other cell surface proteins, including a TNF receptor, the L-selectin adhesion molecule, and transforming growth factor-alpha (TGFalpha). The phenotype of mice lacking TACE suggests an essential role for soluble TGFalpha in normal development and emphasizes the importance of protein ectodomain shedding in vivo.     

Effect of granulocyte macrophage-colony stimulating factor on Langerhans cells in normal and healthy atopic subjects

We conducted a reproducibility study of the alternating breath test (ABT) for assessing peripheral chemoreceptor function in infants. The ABT delivers a rapid hypoxic stimulus to the peripheral chemoreceptors with breath-by-breath alternations of the inspired O2 fraction. The reproducibility of the ABT performed on a single occasion has not been extensively studied in infants. Eight unsedated infants (postnatal age, 22+/-19 d; weight, 3.2+/-0.4 kg) were studied in standardized conditions: morning naps, supine position, room temperature 22-24 degrees C, quiet sleep, and face mask attached to a pneumotachograph connected to a two-way electric valve. Respiratory gases were analyzed by mass spectrometer. Two ABTs were performed. Each included a 2-min control run (CR) alternating between air and air, and a 2-min test run (TR) alternating between air and 0.15 O2. After data preprocessing, on average 13+/-11% of the data were rejected because of sighs, apneas, and cycles with the fraction of inspired oxygen above 0.17. Using the remaining validated breaths, the response to ABT was calculated for the CR, for all breaths in the TR (TR(T)), and for the first 50 breaths of the TR (TR50). During the ABTs oxygen saturation did not fall below 96%, and heart rate was not affected. Inspired and end-tidal CO2 fractions remained unchanged during the ABTs. FetO2 oscillated in TRs at a lower values than in CRs and differed significantly between breaths of air and hypoxic breaths of TRs. All infants responded to ABT with percentage alternation coefficients of TRs significantly greater than those of CRs for all respiratory variables. The values of the coefficients were not significantly different between both ABT, and between TR50 and TR(T). The greatest values of the coefficients were for timing variables compared with flows and volume. We conclude that the ABT is a reproducible test of peripheral chemoreceptor function under standardized conditions.     

Cortical sensorimotor reorganization after spinal cord injury: an electroencephalographic study

The aim of this study was to determine if cortical motor representation and generators change after partial or complete paralysis after spinal cord injury (SCI). Previously reported evidence for a change in cortical motor function after SCI was derived from transcranial magnetic stimulation. These studies inferred a reorganization of the cortical motor system. We applied the new technique of high-resolution EEG to measure changes in cortical motor representation directly. We recorded and mapped the motor potential (MP) of the movement-related cortical potentials in 12 SCI patients and 11 control subjects. Results were analyzed using a distance metric to compare MP locations between patients and control subjects. EEG was coregistered with subject-specific MR images and a boundary element model created for dipole source analysis (DSA). When compared with normal control subjects, seven quadriparetics had posteriorly located MPs with finger movements. One paraparetic had a posterior MP with toe movements, but three who could not move the toes had normally located MPs on attempts to move. DSA confirmed the electrical field map distributions of the MPs. We are reporting a reorganization of cortical motor activity to a posterior location after SCI. These results suggest an important role of the somatosensory cortex (S1) in the recovery process after SCI.     

Processing the head direction cell signal: a review and commentary

Animals require information about their location and directional heading in order to navigate. Directional information is provided by a population of cells in the postsubiculum and the anterior thalamic nuclei that encode a very accurate, continual representation of the animal's directional heading in the horizontal plane, which is independent of the animal's location. Recent studies indicate that this signal 1) arises either in the anterior thalamic nuclei or in structures upstream from it; 2) is not dependent on an intact hippocampus; 3) receives sensory inputs from both idiothetic and landmark systems; and 4) correlates well with the animal's behavior in a spatial reference memory task. Furthermore, HD cells in the anterior thalamic nuclei appear to encode what the animal's directional heading will be about 40 ms in the future, while HD cells in the postsubiculum encode the animal's current directional heading. Both the electrophysiological and anatomical data suggest that the anterior thalamic nuclei and/or the lateral mammillary nuclei may be the sites of convergence for spatial information derived from landmarks and internally-generated cues. Current evidence also indicates that the vestibular system plays a crucial role in the generation of the HD cell signal. However, the notion that the vestibular system is the sole contributor to the signal generator is difficult to reconcile with several findings; these latter findings are better accounted for with a motor efference copy signal.     

Heterologous expression of the lactacin F peptides by Carnobacterium piscicola LV17

The lactacin F complex, composed of LafA and LafX peptides, is produced by Lactobacillus johnsonii VPI 11088 and is active against five other Lactobacillus species and Enterococcus faecalis. The genetic determinants encoding the lactacin F complex are organized in a 1-kb polycistronic operon which comprises three genes, lafA, lafX, and ORFZ (encoding the putative immunity protein). The lafA and lafX genes encode the bacteriocin precursors with N-terminal extensions characterized by a Gly-Gly-1*Xaa+1 cleavage site (*). The Gly-Gly motif is conserved in several other bacteriocins, including carnobacteriocins A, BM1, and B2. Carnobacterium piscicola LV17 produces carnobacteriocins which are active against Listeria monocytogenes and other lactic acid bacteria. In this study, the lactacin F operon was introduced into C. piscicola LV17. The transformants produced lactacin F concurrently with the carnobacteriocins. When the lafA and lafX genes were separated and cloned individually into LV17, production of either LafA or LafX by C. piscicola LV17 was detected by complementation with L. johnsonii clones producing LafX or LafA, respectively. Transformants of C. piscicola LV17 which produced lactacin F, LafA, or LafX, in combination with the carnobacteriocins, were assayed for an increased and expanded inhibitory spectrum. The recombinant organisms were only active against lactacin F- and carnobacteriocin-sensitive strains. A plasmidless derivative of LV17 which does not produce the carnobacteriocins failed to produce lactacin F, LafA, or LafX when transformed with the appropriate recombinant plasmids. The ability of C. piscicola LV17 to produce lactacin F demonstrates that the machinery for the carnobacteriocins is capable of processing and exporting bacteriocins from both systems.