Determination of hepatic acyl-coenzyme A-cholesterol acyltransferase activity in LPN hamsters: A model for cholesterol gallstone formation

Acyl-coenzyme A-cholesterol acyltransferase (ACAT) catalyses the esterification of cholesterol with long-chain fatty acyl-coenzyme A derivatives and has been implicated in the development of cholesterol gallstones. In this study we have examined several key components of the hepatic ACAT assay in order to develop a reliable and sensitive ACAT assay for LPN hamsters, a breed of golden Syrian hamster which has been characterized recently by this laboratory as a particularly good model for studying the pathogenesis of cholesterol gallstones. The newly developed ACAT assays were subsequently used to examine whether hepatic ACAT activity is altered in this animal model. Important new methodological findings were: (i) ACAT activity displayed two pH optima, one at 7.0 when assayed using endogenous cholesterol as substrate, and the other at about pH 8.5–9.0 when assayed in the presence of exogenous cholesterol; (ii) ACAT activity increased markedly when exogenous cholesterol was delivered to ACAT in Tween 80 (125-fold) or hydroxypropyl-β-cyclodextrin (200-fold) in contrast to the use of cholesterol/phosphatidylcholine liposomes (9-fold); (iii) the addition of dithiothreitol, but not reduced glutathione, to the assay mixture resulted in a marked decrease in ACAT activity. Using the optimal assay conditions (exogenous cholesterol added), hepatic ACAT activity was shown to be significantly reduced in hamsters fed a high sucrose lithogenic diet compared with controls (587 ± 42 vs 737 ± 44 pmol/min per mg; P= 0.025). In contrast, ACAT activity measured using endogenous cholesterol as a substrate was greater in sucrose-fed hamsters compared with controls (22.3 ± 2.5 vs 13.2 ± 2.9 pmol/min per mg; P= 0.030). These results highlight the importance of using an ACAT activity assay which has been well characterized and supports the hypothesis that the pathogenesis of cholesterol gallstones in LPN hamsters is related to an altered hepatic cholesterol metabolism.     

Diet Quality and Dietary Diversity in France: Implications for the French Paradox

Objectives Assessing the quality of the total diet is a relatively new focus of studies in nutritional epidemiology. New indexes of healthful eating patterns have been largely limited to US populations. This study used evaluative criteria developed in the United States to assess diet quality and dietary diversity of French adults.Methods Habitual dietary intakes of a representative sample of 837 adults (361 men and 476 women) in the Val-de-Marne Departement were evaluated. Evaluative measures of diet quality included a modified diet quality index (DQI), a dietary diversity (DD) score, and a dietary variety score (DVS). The 5-point DQI assessed compliance with the key guidelines of the US Department of Agriculture (USDA) for healthy people. The DD score counted the number of major food groups consumed whereas the DVS counted the total number of foods consumed on a regular basis.Results Few French adults consumed diets consistent with the USDA dietary recommendations. Only 14% of respondents derived less than 30% of energy from fat and only 4% derived less than 10% of energy from saturated fat. As a result, 63% of the sample had DQI scores of either 0 or 1. In contrast, close to 90% of respondents scored a maximum of 5 in DD. Persons whose diets met US dietary recommendations also had the lowest DVSs.Conclusions Methodologic factors and cultural biases may account for some of the observed differences between French and US data. Nevertheless, studies of diet quality and diversity are a promising new approach to the study of the total diet and associated health outcomes and may provide new insight into the French paradox. J Am Diet Assoc. 1996; 96:663–669.     

Interatrial Conduction in Patients Undergoing AV Stimulation: Effects of Increasing Right Atrial Stimulation Rate

To evaluate the frequency of spontaneous or rate dependent interatrial blocks, the interatrial conduction time (IACT) was studied on 100 consecutive patients (mean age 78.3 ±7.8 years) during a transvenous dual chamber pacemaker implant. The spontaneous interatrial conduction time (SIACT) was measured from the intrinsic deflection (ID) of the unipolar right atrial signal to the ID of the left atrial signal recorded in a bipoiar way by an esophageal lead. The paced interatrial conduction time (PIACT) was measured from the stimulus artifact to the left atrial ID, when the atrium was paced at a slightly higher rate than the spontaneous rate and during incremental atrial pacing. From these measurements, the maximum increase ofPIACT (MIPIACT) was deduced. In this elderly population, the PIACT was similar (117 ± 26.9 msec) to the data in the literature. However, there were large interindividual variations that were also found in SIACT. We found a close correlation between SIACT and PIACT (P < 0.0001). PIACT was on average 50 msec longer than SIACT. SIACT increased with age (P < 0.03). The MIPIACT was 15.3 ± 15.2 msec. In the majority of patients, the MIPIACT was > 10 msec, and even reached 90 msec in one patient. MIPIACT was longer in patients with a PIACT exceeding 110 msec (P < 0.004). Based on IACT alone, the AV interval must be lengthened on average by 50 msec when changing from atrial tracking-ventricular pacing to atrial pacing-ventricular pacing, but large individual differences must be kept in mind. Elderly people should probably have a longer AV delay.     

Importance of Atrial Contraction in Hypertrophic Obstructive Cardiomyopathy: Implications for Pacing Therapy

Hypertrophic cardiomyopathy is a primary myocardial disease characterized anatomically by left ventricular (LV) asymmetric hypertrophy and pathophysiologically by normal or even supernormal systolic ejection performance contrasting with impaired diastolic function. Altered ventricular relaxation tends to reduce the contribution of rapid ventricular filling to total LV filling volumes. Consequently, the contribution of left atrial (LA) contraction can be significantly increased. In some patients LV filling, and thus stroke volume, critically depend upon atrial systole. These data may have important clinical implications especially in patients treated with permanent cardiac pacing. Preserving a fully efficient LA contribution to LV filling is probably a key point in those patients .     

The reorientation of primary health care in Cameroon: rationale, obstacles and constraints

The reorientation of primary health care (PHC) that was begunin Cameroon in 1989 is presented as a natural response to theeconomic and health environments prevailing at that time. Abrief discussion of the original PHC policy introduced followingthe Alma-Ata declaration identifies a lack of effective communicationbetween the community and the health services as a major problem.The basic elements of the reorientation are presented and theobstacles and constraints encountered since beginning the reformprocess in 1989 are described. These have been identified as:an inadequate legal framework; incompatibilities between thepolitical structure and the new health structure; incompatibilitiesbetween the goals of the new health policy and the organizationalchart of the Ministry of Health; the lack of trained personnelin health management; a highly centralized system of managementwith poor coordination of human resource management; the slownessof the extension of PHC coverage; the inability of the systemto ensure that medicines are available and easily accessible;an inadequate health information system; poor promotion of thenew PHC policy; and poor coordination of research activities.     

Disulfide linkage to polyacrylic resin for automated Fmoc peptide synthesis. Immunochemical applications of peptide resins and mercaptoamide peptides

The use of disulfide bonds for peptide–resin linkage in solid-phase peptide synthesis was investigated using polyacrylic polymers (Expansin^TM) and automated Fmoc methodology. The disulfide moiety was bound to the support either by coupling a protected bifunctional handle or by an original stepwise procedure. Among the three different disulfide handles that were investigated, only the aminoethyldithio-2-isobutyric acid (AEDI) handle was stable enough to achieve peptide synthesis. A series of peptides of up to 10–20 amino acids were prepared in this manner, in good yield and purity. Rapid and quantitative peptide release was obtained by reduction with equimolecular amounts of dithiothreitol at pH 9 or tris(2-carboxymethyl) phosphine at pH 4.5. This allowed direct and rapid coupling of the released cysteamide peptides to an activated protein carrier and the use of free or resin-bound forms of the antigen in immunoassays.     

PRIMARY STRUCTURE OF LOBSTER-MUSCLE ARGININE KINASE: Amino and Carboxyl-terminal Structure of the Enzyme and Complete Alignment of the Cyanogen-Bromide Peptides

The acetylation state of the blocked NH₂-terminal end of arginine kinase was characterized by the occurrence of 1 mol acetyl group/mol protein; a 5-residue segment corresponding to the amino-terminal portion was isolated from a pronase digest of the enzyme and its amino acid sequence determined as N-acetyl Ala-Asx-Ala-Ala-Thr. Arginine kinase is terminated at the carboxyl end by the sequence Lys-Glu-MetOH; this particular 3-residue sequence is repeated three times in the overall structure of the protein and is present in three CNBr fragments. One of these, a peptide of 14 amino acid residues, was identified in the course of this study and its amino acid sequence determined. Its location at the COHO-terminal end of the enzyme was recognized on the basis of investigations carried out with des-MetOH-Glu-arginine kinase, a specific proteolytic derivative. The alignment of the eight CNBr-fragments which constitute the arginine kinase molecule was established according to the sequential and compositional properties of seven unique tryptic methionyl peptides isolated from the whole protein. The alignment was confirmed by using BNPS-skatole fragments of the enzyme as another protein source.     

Ultrastructural Aspects of Crystal-Like Inclusions in a Case of IgA Plasma Cell Proliferation

A case of apparently benign plasma cell proliferation is described. Needle-like paracrystalline inclusions were observed in numerous plasma cells outside the cisternae of the rough endoplasmic reticulum. They had a dense protein core surrounded by a layer of carbohydrate. They were found only in plasma cells secreting IgA-kappa immunoglobulin, but did not react with labelled specific antisera. A small amount of paraprotein IgA-kappa was found in the serum but no Bence-Jones protein could be detected in the urine. These observations suggest that these plasma cells synthesize normal IgA immunoglobulin and accumulate abnormal protein in the form of paracrystalline inclusions.