Guinea pig and human cytomegaloviruses do not share cross-reactive neutralizing epitopes.

Human (HCMV) and guinea pig (gpCMV) cytomegaloviruses share biological similarities and DNA sequence homologies. Therefore, human and guinea pig sera were tested for cross-reactive antibodies. In eight human sere (four HCMV-seropositive and four HCMV-seronegative), low levels of neutralizing activity against gpCMV were not associated with antibodies to HCMV. The convalescent sera of one of three humans infected with either HCMV Towne vaccine or wild-type HCMV developed a fourfold increase in neutralizing titers to gpCMV after infection, but none of seven guinea pigs immunized with either HCMV Towne or purified HCMV gB developed neutralizing activity against gpCMV. Guinea pigs immunized with gpCMV did not develop antibodies to HCMV or human gB. Neither gpCMV, HCMV Towne stain or purified HCMV gB induced cross-reactive antibodies against the heterologous virus as detected by enzyme immunoassay. Our results indicate that gpCMV and HCMV share a very limited number, if any, of cross-reactive neutralizing epitopes.

Preparation and interaction of a low-density lipoprotein:daunomycin complex with P388 leukemic cells.

A low-density lipoprotein (LDL):daunomycin complex was prepared which contains, on the average, 8 nmol of daunomycin/mg of apolipoprotein. LDL was not perturbed to any significant degree by association with daunomycin, and the complex remained stable at 4 degrees. Fluorescence quenching with DNA and potassium iodide, antibody precipitation, and density flotation studies suggested at least two domains for localization of the daunomycin, the surface region and the hydrophobic core of the LDL particle. Interaction of the LDL:daunomycin complex with P388 leukemic cells which were sensitive or resistant to daunomycin occurred rapidly in both sublines, with quantitatively larger amounts of the drug being cell associated than when free drug was used alone. The cells appeared morphologically intact, with no nuclear damage after short-term incubation with LDL:daunomycin. Subfractionation of cell membranes and organelles from the sensitive and resistant cell lines incubated with LDL:daunomycin showed accumulation of drug in the plasma membrane and microsomal-lysosomal-mitochondrial membranes and an insoluble nuclear chromatin material. Both 125l-labeled apoprotein and daunomycin from a 125l-LDL:daunomycin complex showed enrichment in similar membrane:organelle fractions of the P388 cells.

Order measurements in plasma membranes from Duchenne dystrophy fibroblasts.

Plasma membranes have been isolated using different methods from Duchenne dystrophy and control human skin fibroblasts. Fluorescence techniques were utilized to resolve the rotational properties and the degree of hindered rotation of the fluorescent probe, 1,6-diphenyl-1,3,5-hexatriene in the membranes. Under specific conditions of fibroblast processing and membrane fractionation, plasma membranes from Duchenne fibroblasts showed significantly less order (0.0125 greater than P less than 0.0025) and less hindrance to probe rotation than membranes from control fibroblasts. The order differences did not seem to be the result of heterogeneity in the membrane environment sampled by the probe. The frequency dependence of the fluorescence lifetime for diphenylhexatriene indicated no measurable contribution by a short lifetime component. Analysis of diphenylhexatriene rotation in the plasma membranes using the 'wobbling-in-cone' theory suggested that both the angle of probe rotation (theta c) and the rotational rate (Dw) were important parameters in understanding the variations between Duchenne and control membranes at 16, 22 and 30 degrees C. Electron spin resonance studies with 5'-doxylstearic acid at 25 degrees C confirmed our fluorescence results. The segmental motion exhibited by the spin label revealed less order in the Duchenne membranes.

Skin capillary changes in early systemic scleroderma. Electron microscopy and "in vitro" autoradiography with tritiated thymidine.

Skin biopsy specimens obtained from involved and noninvolved areas in a patient with early diffuse systemic scleroderma were processed for histology, electron microscopy, and "in vitro" autoradiography with tritiated thymidine. The affected area revealed cellular infiltrates around the eccrine sweat glands, consisting of plasma cells and lymphocytes. The capillaries showed thickening of the basement lamina, damage of endothelial cells, and obstruction of their lumens. However, in some vessels, endothelial cells were preserved and appeared in prophase. Autoradiography with tritiated thymidine showed a marked increase in endothelial and periendothelial cell labeling. Blood immunological studies revealed an increase in B-lymphocytes, IgG, and IgA and the presence of antinuclear and antismooth muscle antibodies.