High osmotic pressure enables fine ultrastructural and cytochemical studies onPneumocystic carinii

High osmotic pressure was used to preserve the ultrastructure of rabbit-, SCID mouse-, and rat-derivedPneumocystis carinii organisms from osmotic stress during fixation. Organelles and cytosol were well preserved within the tonicity range of 850–1,300 mosmol. Under these experimental conditions, we determined that the endoplasmic reticulum was well developed in all parasite stages and could observe the Golgi complex, autophagic vacuoles, dense bodies, type II endoplasmic saccules, and the recently described outer surface membrane, which was found in all parasite stages. The biological implications of these findings are discussed.This investigation was supported in part by the Agence Nationale de Recherche sur le SIDA (ANRS) and in part by a scholarship awarded by the Conseil Régional Nord-Pas-de-Calais (to F.P.) during the course of the study.     

Experimental considerations in biological ESR studies. I. Identity and origin of the 'tissue lipid signal': a copper-dithiocarbamate complex.

The complex ESR signal previously observed in fatty tissues has been identified. It is a copper low-molecular-weight sulphur compound complex similar to copper-dithiocarbamate. The usual source of this signal is contact of copper-containing tissue with surgeon's gloves. This result emphasizes the care that must be taken in obtaining and interpreting ESR spectra of tissues. The formation of this complex by intentionally adding dithiocarbamate to tissue can be used as a very simple and sensitive analytical method for tissue copper. Copper levels of less than 0-1 ppm can be detected by this method. This is an order of magnitude more sensitive than determinations by atomic absorption.     

Passive immune complex glomerulonephritis in mice: models for various lesions found in human disease. I. High avidity complexes and mesangiopathic glomerulonephritis.

Intravenous injection of mice with soluble complexes of highly avid rabbit antibody to egg albumin, prepared by dissolution of equivalence precipitates in large quantities of antigen, resulted in a purely mesangial localization of the complexes. When animals received three injections of complexes per day for 1 day it was noted that precipitates dissolved in 80 times the equivalence amount of antigen produced slight mesangial changes. When such complexes were injected for 2 or 3 days, outright mesangiopathic glomerulonephritis was observed in an increasing proportion of the animals. Equivalent amounts of antigen alone did not produce lesions.