Comparison of the effects of a preliminary hepatic washing and of saponin on the intracellular penetration of peroxidase-labeled anti-rat albumin antibodies in hepatocytes

Summary The effects of a preliminary hepatic washing with saline before liver fixation either by perfusion or immersion was compared to the effect of saponin, a membrane-permeabilizing agent, in order to ascertain which procedure is best to obtain a homogeneous distribution of albumincontaining hepatocytes in the hepatic lobule. Albumin was located in the hepatocytes by peroxidase-labeled antibodies using light and electron microscopy. The efficacy of the two procedures on the intracellular penetration of labeled antibodies in liver sections was judged by preparing transverse ultrathin sections. Both procedures yielded similar results. Liver fixation by perfusion with saponin and without a preliminary washing, however, distributes albumin-containing hepatocytes more homogeneously in the hepatic lobule and enables labeled antibodies to penetrate more satisfactorily. In contrast, when the liver is fixed by immersion, the preliminary washing is the only way to obtain an even distribution of albumin-containing hepatocytes, as saponin is not effective under these conditions. In conclusion, the localization of albumin in the hepatocytes must be adapted according to the technique used to fix the liver.     

Interactive computer surface graphic study of the binding of an antibody to the chromatin subunit

The binding of an IgG molecule to a chromatin subunit has been simulated by the interactive computer surface graphics technique. This technique permits the facile display of the surface of macromolecules for which atomic co-ordinates are known. The computer generated projections reveal spatial relationship between the IgG and the nucleosome. Studies of these projections provide insights into the immunogenicity and antigenicity of the chromatin subunit. The concepts discussed are helpful in understanding the manner in which IgG molecules specific to DNA bases, chromosomal proteins, irradiated DNA and to chemical carcinogens bind to the genome.     

Stimulation of the α7 Nicotinic Acetylcholine Receptor Protects against Neuroinflammation after Tibia Fracture and Endotoxemia in Mice

Surgery and critical illness often associate with cognitive decline. Surgical trauma or infection can lead independently to learning and memory impairments via similar, but not identical, cellular signaling of the innate immune system that promotes neuroinflammation. In this study we explored the putative synergism between aseptic orthopedic surgery and infection, the latter reproduced by postoperative lipopolysaccharide (LPS) administration. We observed that surgery and LPS augmented systemic inflammation up to postoperative d 3 and this was associated with further neuroinflammation (CD11b and CD68 immunoreactivity) in the hippocampus in mice compared with those receiving surgery or LPS alone. Administration of a selective α7 subtype nicotinic acetylcholine receptor (α7 nAChR) agonist 2 h after LPS significantly improved neuroinflammation and hippocampal-dependent memory dysfunction. Modulation of nuclear factor-kappa B (NF-κB) activation in monocytes and regulation of the oxidative stress response through nicotinamide adenine dinucleotide phosphate (NADPH) signaling appear to be key targets in modulating this response. Overall, these results suggest that it may be conceivable to limit and possibly prevent postoperative complications, including cognitive decline and/or infections, through stimulation of the cholinergic antiinflammatory pathway.     

An Arabidopsis brassinosteroid-dependent mutant is blocked in cell elongation.

Cell elongation is a developmental process that is regulated by light and phytohormones and is of critical importance for plant growth. Mutants defective in their response to light and various hormones are often dwarfs. The dwarfed phenotype results because of a failure in normal cell elongation. Little is known, however, about the basis of dwarfism as a common element in these diverse signaling pathways and the nature of the cellular functions responsible for cell elongation. Here, we describe an Arabidopsis mutant, dwarf4 (dwf4), whose phenotype can be rescued with exogenously supplied brassinolide. dwf4 mutants display features of light-regulatory mutants, but the dwarfed phenotype is entirely and specifically brassinosteroid dependent; no other hormone can rescue dwf4 to a wild-type phenotype. Therefore, an intact brassinosteroid system is an absolute requirement for cell elongation.     

Hepatitis B vaccine safety monitoring in the chimpanzee: interpretation of results

In September, 1983, a group of French and American experts met at the French National Health Laboratory to discuss their experience in monitoring for the safety of a hepatitis B vaccine in 42 chimpanzees. The observations made, conclusions reached, and recommendations for future studies are presented.     

Studies on the methodology and evaluation of the lymphocyte transformation microtest

Optimum experimental conditions for the lymphocyte transformation microtest in healthy persons are described. The dependence of PHA stimulation on duration of culture, additions of serum and PHA concentration is investigated. A function of normal distribution pattern can be set up by determining the lymphocyte stimulability with four different PHA concentrations in the optimal stimulation range. With this function, the area under the curve, steepness, position and height of the maximum can be calculated. These parameters should serve for better interpretation of cellular immunity.