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Characterization of the serum lipoproteins and their apoproteins in hypercholesterolaemic guinea pigs.

ABSTRACT: 1. Hypercholesterolaemia was induced in male guinea pigs after 6 days on a chow diet supplemented with 1.6% (w/w) cholesterol and 15% (w/w) corn oil. Both the VLD (very-low-density) and LD (low-density) lipoproteins were increased in cholesterol-fed animals, although the low concentrations of HD (high-density) lipoproteins remained essentially unchanged. LD lipoproteins of d 1.019-1.100 were the major class, accounting for 74% of the total substances of d less than 1.100. 2. Both VLD and LD lipoproteins exhibited alterations in their chemical composition, physical properties and apolipoprotein content. The VLD lipoproteins in cholesterolaemic animals were rich in cholesterol (25.9%), deficient in protein (4.9%) and exhibited electrophoretic mobility greater than that of beta-globulin; their average particle size (64.5 nm) was larger than that in controls (46.3 nm). The LD lipoproteins in animals fed on the experimental diet were also richer in cholesterol (53.1%) and of larger diameter (24.3 nm) than in the control group (41.1% and 21.4 nm respectively). 3. The apolipoprotein-B content of both VLD and LD lipoproteins was elevated in cholesterolaemic animals, particularly in the VLD class, where it represented 74.8% of the total protein moiety. 4. Apo-VLD lipoprotein exhibited an increase from 6 to 19% in its complement of tetramethylurea-soluble apolipoproteins with low electrophoretic mobility (relative mobility less than 0.29); this was primarily accounted for by apolipoproteins characterized by high arginine (7.2 and 6.4% respectively) and glutamic acid (20.1 and 20.0% respectively) contents. 5. By contrast, there was little change in the soluble apolipoproteins of LD lipoproteins in hypercholesterolaemic animals.6. These studies show the response of the guinea pig to dietary fat and cholesterol to be distinct from that elicited by similar stimuli in the rabbit, rat, pig and dog.

SUBMITTER: Chapman MJ

PROVIDER: S-EPMC1183616 | biostudies-other | 1977 Oct

REPOSITORIES: biostudies-other

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Project description:Ebola virus (EBOV) transmission is currently poorly characterized and is thought to occur primarily by direct contact with infectious material; however transmission from swine to nonhuman primates via the respiratory tract has been documented. To establish an EBOV transmission model for performing studies with statistical significance, groups of six guinea pigs (gps) were challenged intranasally (i.n.) or intraperitoneally (i.p.) with 10,000 times the 50% lethal dose (LD50) of gp-adapted EBOV, and naive gps were then introduced as cage mates for contact exposure at 1 day postinfection (p.i.). The animals were monitored for survival and clinical signs of disease and quantitated for virus shedding postexposure. Changes in the duration of contact of naive gps with infected animals were evaluated for their impact on transmission efficiency. Transmission was more efficient from i.n.- than from i.p.-challenged gps, with 17% versus 83% of naive gps surviving exposure, respectively. Virus shedding was detected beginning at 3 days p.i. from both i.n.- and i.p.-challenged animals. Contact duration positively correlated with transmission efficiency, and the abrogation of direct contact between infected and naive animals through the erection of a steel mesh was effective at stopping virus spread, provided that infectious animal bedding was absent from the cages. Histopathological and immunohistochemical findings show that i.n.-infected gps display enhanced lung pathology and EBOV antigen in the trachea, which supports increased virus transmission from these animals. The results suggest that i.n.-challenged gps are more infectious to naive animals than their systemically infected counterparts and that transmission occurs through direct contact with infectious materials, including those transported through air movement over short distances.Ebola is generally thought to be spread between humans though infectious bodily fluids. However, a study has shown that Ebola can be spread from pigs to monkeys without direct contact. Further studies have been hampered, because an economical animal model for Ebola transmission is not available. To address this, we established a transmission model in guinea pigs and determined the mechanisms behind virus spread. The survival data, in addition to microscopic examination of lung and trachea sections, show that mucosal infection of guinea pigs is an efficient model for Ebola transmission. Virus spread is increased with longer contact times with an infected animal and is possible without direct contact between an infected and a naive host but can be stopped if infectious materials are absent. These results warrant consideration for the development of future strategies against Ebola transmission and for a better understanding of the parameters involved in virus spread.

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Characterization of the serum lipoproteins and their apoproteins in hypercholesterolaemic guinea pigs.

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