ULTRASTRUCTURAL ANALYSES OF STONE HEART SYNDROME AT ONSET AND SIX DAYS LATER FOLLOWING TOTAL SUPPORT OF THE CIRCULATION WITH A PARTIAL ARTIFICIAL HEART OR LEFT VENTRICULAR ASSIST DEVICE (ALVAD)

Ischemic myocardial contracture developed in a 21-year-old man following aortic and mitral valve replacement. The patient's circulation was supported totally for 6 days with an abdominal left ventricular assist device (ALVAD). Cardiac allografting was then undertaken. Samples of myocardium taken at the original operation and 6 days later at transplantation were analyzed ultrastructurally. At the onset of ischemic cortracture, left ventricular abnormalities included hypercontraction of myofibrils, loss of normal A-band and Z-band patterns, mitochondrial swelling with fusion of cristae, interfibrillar edema and glycogen depletion. Capillaries demonstrated swelling of endothelial cells and basement membrane disruption. Six days later, ultrastructural morphology showed further degeneration. The myofibrils remained hypercontracted, but were more fragmented. Degenerative changes in mitochondria were more advanced and calcium deposition in cristae was present. No glycogen was seen. The right ventricular myocardium exhibited significantly fewer ultrastructural abnormalities. The principal right ventricular changes were endothelial swelling and basement membrane disruption. Glycogen granules were present. Ischemic contracture affects the left ventricle more than the right, and the morphology becomes more abnormal with time. To our knowledge, this is the first instance wherein morphologic progressions of the ultrastructural alterations of ischemic contracture have been documented.     

An ultrastructural and cytochemical study of the interaction between latex particles and the haemocytes of the wax moth Galleria mellonella in vitro

Summary The plasmatocytes are the major phagocytic blood-cell type in the haemolymph of the wax-moth, Galleria mellonella. In the present study, these cells were allowed to attach to tissue culture dishes for 1 h, rinsed and then incubated with latex beads for up to 72 h. These cells were then fixed for routine transmission electron microscopy and acid phosphatase cytochemistry. Intracellular latex particles were found in tight, ill-defined phagosomes, which were often clearly associated with the Golgi complexes of the plasmatocytes. Fusion of both primary lysosomes and multivesicular bodies with the phagosomes occasionally occurred and this resulted in the accumulation of an acid phosphatase positive reaction product around the test particles. Subsequent experiments showed that this acid phosphatase activity was mainly associated with the primary lysosomes. The results of the lysosome/latex interactions are compared with those obtained from similar studies on the digestive mechanisms in other phagocytes.We are grateful to Professor E.W. Knight-Jones in whose department this work was carried out and to Mrs. M. Colley for help in insect rearing. This work was supported by grants from the Royal Society and the Science Research Council (B/73/0176. and B/RG/2286.0)     

Improved methods for the formation and stabilization of R-loops

Improved methods for the formation and stabilization of R-loops for visualization in the electron microscope are presented. The two complementary strands of a duplex DNA are photochemically crosslinked once every 1 to 3 kb using 4, 5', 8 trimethylpsoralen. R-loops are then formed by incubation with RNA in 70% formamide at a temperature above the DNA melting temperature. Finally, the R-loops are stabilized by modifying the free single strand of DNA with glyoxal, thus minimizing the displacement of the hybridized RNA by branch migration. In this manner R-loops can be formed and visualized at a high frequency irrespective of the base composition of the nucleic acid of interest.     

Preparation of (aryl α-l-idopyranosid)uronic acids

The earlier preparation of cyclohexylammonium (phenyl α-l-idopyranosid)-uronate has been improved, and (4-methylumbelliferyl α-l-idopyranosid)uronic acid (14), a more sensitive substrate for α-l-iduronidase, has been synthesized by an analogous route. Zinc chloride-catalyzed condensation of 4-methylumbelliferone with 1,2,3,4,6-penta-O-acetyl-α-l-idopyranose (4) in 1,2-ethanediol diacetate gave crystalline 4-methylumbelliferyl 2,3,4,6-tetra-O-acetyl-α-l-idopyranoside (7). O-Deacetylation and catalytic oxidation gave 14, characterized as a cyclohexylammonium salt. The starting material 4 was prepared, in 21 % yield from l-glucose, by conversion of the intermediate 1,2,3,4,6-penta-O-acetyl-β-l-glucopyranose to 2,3,4,6-tetra-O-acetyl-β-l-glucopyranosyl chloride and acetoxonium ion rearrangement, as described for the D-series.     

Preparation of (aryl α-l-idopyranosid)uronic acids

The earlier preparation of cyclohexylammonium (phenyl α-l-idopyranosid)-uronate has been improved, and (4-methylumbelliferyl α-l-idopyranosid)uronic acid (14), a more sensitive substrate for α-l-iduronidase, has been synthesized by an analogous route. Zinc chloride-catalyzed condensation of 4-methylumbelliferone with 1,2,3,4,6-penta-O-acetyl-α-l-idopyranose (4) in 1,2-ethanediol diacetate gave crystalline 4-methylumbelliferyl 2,3,4,6-tetra-O-acetyl-α-l-idopyranoside (7). O-Deacetylation and catalytic oxidation gave 14, characterized as a cyclohexylammonium salt. The starting material 4 was prepared, in 21 % yield from l-glucose, by conversion of the intermediate 1,2,3,4,6-penta-O-acetyl-β-l-glucopyranose to 2,3,4,6-tetra-O-acetyl-β-l-glucopyranosyl chloride and acetoxonium ion rearrangement, as described for the D-series.     

Comparative Membrane Microviscosity of Fish and Mammalian Rhabdoviruses Studied by Fluorescence Depolarization

The microviscosity of the hydrophobic region of the membrane of infectious hematopoietic necrosis virus was determined using fluorescence depolarization analysis of the probe 1,6-diphenyl-1,3,5-hexatriene and was found to be much lower at 37 C than that of another rhabdovirus, vesicular stomatitis virus. However, the microviscosity of this fish virus at 18 C, the temperature at which it was grown, corresponded to the microviscosity of vesicular stomatitis virus at 37 C. Data obtained with the fish virus host cell (chinook salmon embryo cells) grown at 18 C suggest that its membranes have a lower microviscosity than either L-929 or BHK-21 cells (the vesicular stomatitis virus host cells) grown at 37 C.     

In vitro synthesis and repression of argininosuccinase in Escherichia coli K12; partial purification of the arginine repressor

Summary 80dargECBH DNA has been used to direct cell-free synthesis of argininosuccinase, the argH gene product in Escherichia coli K12. In vitro enzyme synthesis is sensitive to repression by partially purified preparations from an argR ⁺ strain but not by corresponding preparations from an argR ^- strain. Using DNA-cellulose chromatography, approximately seventyfold purification of repressor has been obtained. The partially purified preparation represses argininosuccinase synthesis but has no effect on -galactosidase synthesis.