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J Chapman

Publications and source records attributed to J Chapman.

At least 271 records · Page 15Linked to original sources

[Lipoprotein Lp(a) and CETP (cholesterol ester transfer protein): contribution of transgenic mice].

Lipoprotein Lp(a) is a pluri-molecular complex rich in cholesterol and composed of an LDL (low-density lipoprotein) particle to which is attached a large glycoprotein, apolipoprotein(a) (apo(a)). Numerous epidemiological studies have established a strong correlation between plasma levels of Lp(a) and the premature development of atheromatous vascular disease in man, an association which has subsequently been confirmed by the detection of Lp(a) in human atherosclerotic plaques. Furthermore, a marked structural resemblance has been demonstrated between apo(a) and plasminogen, a key protein of the fibrinolytic system and responsible for dissolution of blood clots. This discovery has provided evidence, for the first time, that Lp(a) might constitute an important link between atherosclerosis and thrombosis. Intense research effort is now underway to provide further understanding of (I) the structural organisation of the Lp(a) particle; (II) the molecular genetics of apo(a); (III) the processes involved in the synthesis, assembly intravascular metabolism and degradation of Lp(a) and apo(a); (IV) the nature of the interactions of Lp(a) and apo(a) with cellular and non-cellular components of the arterial wall; (V) the role of Lp(a) in fibrinolysis, and (VI) the relationship between Lp(a) and certain metabolic disorders such as familial hypercholesterolemia. These fascinating questions will be examined in the light of studies of different models of transgenic mce expressing human apo(a) alone, or both apo(a) and apo B100. In man, CETP assures the transfer of cholesteryl ester from high-density lipoproteins (HDL) to lipoproteins containing apo-B, and notably VLDL, IDL and LDL.(ABSTRACT TRUNCATED AT 250 WORDS)

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Lipoprotein[a] in the chimpanezee: relationship of apo[a] phenotype to elevated plasma Lp[a] levels.

Several studies have documented the presence of Lp[a] in nonhuman primates. However, data are lacking in great apes such as the chimpanzee. We have studied the quantitative distribution of Lp[a], as well as the frequency of apo[a] phenotypes, in a population of chimpanzees living in Gabon. Monoclonal antibody 14A12, directed against human apo[a], failed to recognize chimpanzee Lp[a]. Therefore, Lp[a] was assayed using an ELISA involving two polyclonal antibodies, an anti-human apo[a] and an anti-human apoB-100. Under these conditions, Lp[a] was detected in each of 28 animals. The plasma level of Lp[a] was found to be highly skewed toward elevated values: the mean Lp[a] level was 0.61 mg/ml (SD 0.45) as compared to 0.18 mg/ml (SD 0.16) in a normal Caucasian population (P < 0.0001). Phenotypes for apo[a] were identified by SDS-agarose-gel electrophoresis, followed by immunoblotting and detection by chemiluminescence. Seventeen different isoforms (ranging from 440 to 920 kDa) were found among all the animals as compared to 19 (540 to 960 kDa) in a human population of equivalent number. However, the distribution of apo[a] phenotypes was distinct between these populations. Thus isoforms of low molecular mass occurred with greater frequency in chimpanzee as compared to humans. In both populations, a strong inverse correlation between Lp[a] levels and apo[a] isoform sizes was found in chimpanzees (r = -0.48; P < 0.01) and in man (r = -0.68; P < 0.0002).(ABSTRACT TRUNCATED AT 250 WORDS)

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Brainstem auditory evoked potentials in experimental autoimmune dementia.

Cognitive dysfunction may be induced in rats by immunization with cholinergic neuronal antigens and is associated with degeneration of nuclei in the septum and hippocampus and white matter tracts in the forebrain. Such rats are a putative model of Alzheimer's disease named experimental autoimmune dementia (EAD). The aim of the present study was to investigate brainstem auditory evoked potentials (BAEP) in EAD rats in order to define the extent of white matter tract involvement in this model. Clear reproducible evoked potentials were obtained and the normal range of BAEP in rats was established in adjuvant immunized controls. Measurements of inter peak latencies (IPL) I-IV in 9 EAD rats revealed that they were not significantly prolonged (3.00 +/- 0.22 ms, mean +/- S.E.M.) compared to 9 controls (2.80 +/- 0.08 ms), (P > 0.2, Student's t-test). The lack of significant change in IPL I-IV is compatible with preliminary histological findings and indicates that brainstem structures are generally unaffected in EAD.

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