Thermal analysis of human plasma low density lipoproteins reveals a broad reversible transition encompassing body temperature. The calorimetric and x-ray scattering data identify this transition as a cooperation, liquid-crystalline to liquid phase change involving the cholesterol esters in the lipoprotein. This behavior requires the presence of a region rich in cholesterol ester within the lipoprotein.

Human neutrophils, when stimulated with phorbol myristate acetate or fMet-Leu-Phe in the presence or absence of cytochalasin B, released metalloproteinases that catalytically inactivated the plasma serine proteinase inhibitor, a1-antitrypsin. Inactivation, measured as loss of elastase inhibitory capacity, was accompanied by cleavage of a M, 4,000 peptide from the COOH-terminus. Cleavage of a1-antitrypsin by cell supernatants was inhibited by EDTA, o-phenanthroline, and DTT, but not by inhibitors of serine or thiol proteinases. Gelatinase and collagenase were separated from the medium of stimulated neutrophils. Both preparations cleaved and inactivated a,-antitrypsin, with cleavage occurring close to the reactive center, at the Phe-Leu bond between positions P7 and P6. Cleavage by purified gelatinase was very slow and could account for only a minor fraction of the activity of neutrophil supernatants. The collagenase preparation was more active. However, the unusual cleavage site, and the ability of fMet-Leu-Phe-stimulated neutrophils to cleave a1-antitrypsin without releasing collagenase, suggests that collagenase is not responsible for cleavage by the cells, which, by implication, is due to an as yet uncharacterized metalloenzyme. Our results demonstrate that by releasing metalloproteinases, neutrophils could proteolytically inactivate a,-antitrypsin at sites of inflammation. This provides an alternative to the previously documented mechanism of inactivation by neutrophil-derived oxidants.

The significance of subclinical thiamine deficiency in the elderly was determined by assessing response to thiamine supplementation in a randomized double-blind, placebo-controlled trial. Thirty-five of 222 people aged > or = 65 y had two concentrations of erythrocyte thiamine pyrophosphate (TPP) < 140 nmol/L 3 mo apart and 41 other people had the first, but not the second, TPP concentration below this value. Both groups were randomly assigned in a double-blind trial to oral thiamine (10 mg/d) or a placebo. All subjects randomly assigned to receive thiamine showed increases in TPP concentrations compared with control subjects. Only the subjects with persistently low TPP concentrations showed subjective benefits from treatment with improvements in quality of life (measured on a visual analogue scale; P = 0.02) and decreases in systolic blood pressure (P = 0.05) and weight (P < 0.01) when compared with subjects given placebo. There was a trend toward benefits in sleep and energy (P = 0.07). We conclude that a low TPP concentration on two occasions is a better predictor of response to treatment than an isolated measurement. Quality of life was enhanced by providing thiamine supplements. Blood pressure and weight were lower after thiamine supplementation.

Hyperlipidemia is a major risk factor for atherosclerosis and probably contributes to the increased cardiovascular mortality following renal transplantation. We studied the lipid profiles of 62 adults (29 males) with stable renal function (mean plasma creatinine 0.14 mmol/l, SD 0.07), 7 months to 21 years after renal transplantation. Fifteen patients (24%) were above the age- and sex-adjusted 95th percentile for total triglyceride and 10 (16%) for total cholesterol concentrations when compared with a local reference population. The most common lipoprotein abnormalities were type IIa (19%) and type lib (13%). Multiple regression analysis demonstrated that the use of diuretics and angiotensin-converting enzyme inhibitors were significant factors determining plasma triglyceride concentrations. There were significant bivariate associations between plasma triglyceride concentration and duration since transplantation, plasma creatinine concentration and the use of ciclosporin and diuretics. Duration since transplantation and ciclosporin use were significant factors determining lower plasma cholesterol concentrations. The use of ciclosporin and diuretics was associated with a significantly higher apolipoprotein (apo) B concentration. The cholesterol/HDL cholesterol risk ratio correlated poorly with the apo B/apo A-1 ratio. The value of these ratios as predictors of coronary artery disease need to be established in renal transplant recipients.

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