Association of lipoprotein(a) concentration and apo(a) isoform size with restenosis after percutaneous transluminal coronary angioplasty

Lp(a) is a unique class of lipoprotein particles that exhibits a considerable size heterogeneity resulting from the size polymorphism of apo(a), its unique protein component. An elevated level of Lp(a) in plasma has been proposed to be a risk factor for premature development of coronary artery disease. To evaluate the relationship between Lp(a) concentration and apo(a) isoform size with restenosis after percutaneous transluminal coronary angioplasty, Lp(a) levels and apo(a) phenotypes were determined in 204 patients who underwent a successful coronary angioplasty procedure and stent implantation. The patients were followed with clinical examinations and exercise tests at 1, 3, and 6 months, and a control coronary angiography was performed after 6 months to evaluate restenosis. Lp(a) levels were determined with an ELISA that is insensitive to the size heterogeneity of Lp(a), and the apo(a) isoforms were determined by a high-resolution agarose gel electrophoresis method followed by immunoblotting with a specific monoclonal antibody. Of the 146 patients who underwent angiographic evaluation, 57 (39%) had restenosis, whereas 89 (61%) did not. Lp(a) levels and the distribution of the expressed apo(a) phenotypes were compared in these two groups of patients. Although the mean and median Lp(a) levels were higher in the restenosed group, the difference was not statistically significant. However, a significant difference in Lp(a) values was found in women (P=0.043), even though, because of the small number of women in the study (n=35), no sound conclusions can be reached on the predictive role of Lp(a) in restenosis. There also was no difference in the distribution of apo(a) phenotypes between the two groups. Because of their wide distribution, Lp(a) values and apo(a) isoforms do not seem to be a useful indicator of risk of restenosis after percutaneous transluminal coronary angioplasty in our study cohort

The effect of different protease inhibitors on stability of parathyroid hormone, insulin, and prolactin levels under different lag times and storage conditions until analysis

IntroductionProteolytic cleavage through proteases affects peptide hormone levels, which is of particular significance when the time interval between sampling and analysis is prolonged. We evaluated the stability of parathyroid hormone, insulin, and prolactin molecules (i) with different protease inhibitors such as K(2)EDTA, aprotinin, and protease inhibitor cocktail (PIC), (ii) with different lag times (6-72hours), and (iii) under different storage temperatures (4 degrees C vs room temperature [RT]) until analysis. Materials and MethodsBlood samples were collected into 2 sets of 5 Vacutainer((R)) tubes (Becton Dickinson) from 10 healthy adults. Tubes 1 and 2 were plain gel separator tubes. Tubes 3, 4, and 5 contained PIC (1%), aprotinin (500 KIU/mL), and K(2)EDTA, respectively. After centrifugation at 1300g for 10minutes, PIC added to tube 2 of each set. Samples were analyzed and then one set was stored at 4 degrees C, whereas the other at RT until analysis at 6, 24, 48, and 72hours. Hormone levels were determined with electrochemiluminescence immunoassay (ModularE170; Roche Diagnostics). The results were compared with desirable bias limits (DBL) from Westgard QC database. ResultsInsulin at RT decreases exceeding the DBL starting from 24hours and K(2)EDTA preserved insulin. PTH exceeded the DBL at RT for 48hours or longer and PIC addition after centrifugation inhibited its degradation. Prolactin remained stable in all tested conditions. All parameters in the plain gel separator tubes remained within DBL when stored at 4 degrees C until 72hours. ConclusionsDifferent proteases may degrade peptide hormones and measures should be taken to counteract these effects especially if there is a delay before analysis

Adenosine deaminase activity and zinc levels in the serum of patients with diabetes mellitus

Objective: Adenosine deaminase (ADA) specifically catalyzes the deamination of adenosine which has been proved to play an important role in modulation of insulin action on glucose metabolism. Zinc is an essential micronutrient that is directly involved in the physiology of insulin and may be an important agent to activate the ADA. We aimed to evaluate serum ADA activity, zinc levels and the relationship between these two parameters in diabetes mellitus. Methods: We investigated serum ADA activity and zinc levels in type I (n = 100) and type II diabetes mellitus patients (n = 151). Results: ADA activities of diabetic patients were significantly elevated, whereas zinc levels were significantly lower than those of healthy controls (p 8%) showed significantly increased ADA activity (p 0.05). Conclusion: Elevated ADA activity in diabetic patients with poor glycemic control may be a useful marker for therapy modulation

Macroprolactin does not contribute to elevated levels of prolactin in patients on renal replacement therapy

Objective Three molecular forms of PRL with molecular weights of 23, 50-60 and > 100 kDa have been defined. The high-molecular-weight forms are called macroprolactin. Different immunoassays produce varyingly elevated results with macroprolactin-containing sera. The kidneys are reported to clear 25% of PRL from the circulation. Hyperprolactinaemia is seen in 20-75% of patients with chronic renal failure (CRF). PRL clearance rate has been reported to be reduced in CRF and the resulting hyperprolactinaemia is due to reduced renal function. Patients To determine the contribution of macroprolactinaemia to elevated PRL levels in CRF, 91 patients receiving haemodialysis (HD), continuous ambulatory peritoneal dialysis (CAPD) and renal transplantation (RT) therapies and 72 control subjects were included in the study. Measurements Serum PRL levels were measured by a sandwich immunoassay with electrochemical detection. Following polyethylene glycol (PEG) precipitation, recovery ratios were calculated and samples with a recovery of 0.05). A moderate correlation was found between PRL and creatinine levels (r = 0.609, P < 0.001). Conclusions The hyperprolactinaemia seen in renal replacement therapy is not associated with the presence of macroprolactin isoforms but with the decline in renal function

A case of falsely elevated D-dimer result

Objectives Heterophile antibodies can cause interferences in immunometric assays. While many tests are shown to be affected by interference from heterophilic antibodies, the D-dimer test has rarely been reported to be affected. With this case, we report an elevated D-dimer measurement which was not compatible with the clinical presentation. Case presentation A 41-year-old patient who was admitted to hospital with heart palpitations had a D-dimer elevation irrelevant to his clinical condition. D-dimer measurements were repeated in new samples directly and after being treated in heterophilic blocking tube with two different reagent lots of a latex-based automated immunoturbidimetric assay and an immunoturbidometric assay. D-dimer values were normalized (0-0.5 mg/L) when we used a new lot of reagent on the same instrument or measured by an immunoturbidometric method on the chemistry analyzer. After treatment with HBT, all samples revealed D-dimer results within the reference ranges. Conclusions The presence of heterophile antibodies in a sample should be considered when an elevated D-dimer value that is not compatible with the clinical presentation is encountered. Apart from the patient\"s HA\"s causing false results, sporadic susceptibility of the reagents should also be kept in mind as a possibility

Serum Adipokine Levels in Type 1 Diabetic Patients: Association with Carotid Intima Media Thickness

Background: Adipokines are markers of insulin resistance and play a role in the atherosclerotic process. The association of adipokines with the macrovascular complications of type 1 diabetes mellitus (DM) needs to be determined. The aim of this study was to measure serum adiponectin, leptin, and resistin levels in type 1 DM patients and investigate their relationship with carotid intima media thickness (CIMT), a clinical marker of atherosclerosis. Methods: Seventy-five type 1 DM patients and 115 sex and age-matched healthy controls were included in the study. Serum adiponectin, leptin, and resistin levels were measured by the enzyme-linked immunosorbent assay (ELISA method). CIMT was assessed by Doppler ultrasonography Results: Adiponectin levels in diabetics were higher (25.8 +/- 14.8 mg/mL vs. 5.5 +/- 7.3 mg/mL; P<0.0001) and leptin levels were lower than controls (9.4 +/- 6.2 ng/mL vs. 12.8 +/- 8.6 ng/mL; P=0.01). Resistin levels were also higher in the diabetic group compared to controls (2.1 +/- 1.4 ng/mL vs. 1.6 +/- 0.8 ng/mL; P=0.04). Adiponectin was correlated negatively with CIMT (r=-0.24, P=0.03), age (r=-0.30, P=0.02), BMI (r=-0.33, P=0.02), waist-to-hip ratio (WHR) (r=-0.38, P=0.01) and positively with creatinine (r=0.44, P=0.004). Leptin levels were correlated with total cholesterol (r=0.53, P=0.01) and high-density lipoprotein (HDL) (r=0.67, P=0.001). Resistin was correlated with CIMT (r=0.24, P=0.03) and systolic blood pressure (r=0.48, P=0.009). Multivariate analysis revealed resistin and creatinine to be independent predictors of CIMT among adiponectin, leptin, resistin, WHR, glycosylated hemoglobin (HbA1c), and creatinine. Conclusions: Increased adiponectin correlates negatively and resistin positively with CIMT in type 1 diabetic patients, but adjusting for other known predictors reveals only resistin to be associated with subclinical atherosclerosis in this group of patients

Dietary cholesterol-induced changes of protein kinase C and the effect of vitamin E in rabbit aortic smooth muscle cells

The changes occurring in smooth muscle cells during the development of atherosclerosis in rabbits fed 2% cholesterol and the effect of vitamin E treatment were investigated. Ex-vivo smooth muscle cells obtained from the aorta of cholesterol-fed rabbits exhibited a 2-fold increase of protein kinase C expression and activity. The cholesterol induced changes in protein kinase C were equally present in the membrane bound and cytosolic fraction of the enzyme. The amount of a control protein cc-actin was not affected in smooth muscle cell by the high cholesterol diet treatment, indicating that protein kinase C increase was specific. The increase of protein kinase C expression and activity was not significantly affected by vitamin E treatment although a constant trend was noted. The data are discussed in the light of previous smooth muscle cell in vitro experiments

Effect of vitamin E and probucol on dietary cholesterol-induced atherosclerosis in rabbits

The preventive effect of vitamin E and Probucol against atherosclerosis in rabbits were compared. Atherosclerosis was induced by a 2% cholesterol-containing vitamin E-poor diet (5-10 ppm). Six groups of five rabbits each were studied. Group I (control) was fed on a vitamin E-poor diet. The other groups had the following supplements: group II, 50 mg/kg vitamin E i.m.; group III, 2% cholesterol; group IV, 2% cholesterol plus 50 mg/kg vitamin E i.m., group V, 2% cholesterol plus 1% Probucol; group VI, 2% cholesterol + 1% Probucol plus 50 mg/kg vitamin E i.m. After 4 weeks, aortas were removed and analyzed by light and scanning electron microscopy for atherosclerotic lesions. Samples of the media were analyzed for protein kinase C activity. The aortas of cholesterol-fed rabbits showed typical atherosclerotic lesions, detected by microscopic examination, their media smooth muscle cells exhibited an increase in protein kinase C activity. Vitamin E fully prevented cholesterol-induced atherosclerotic lesions and the induction of protein kinase C activity. Probucol was not effective in preventing either cholesterol-induced atherosclerotic lesions or the induction of protein kinase C activity. These results show that the protective effect of vitamin E against hypercholesterolemic atherosclerosis is not produced by an other antioxidant such as Probucol, and therefore, may not be linked to the antioxidant properties of this vitamin. The effects observed at the level of smooth muscle cells ex vivo suggest an involvement of signal transduction events in the protective effect of vitamin E against atherosclerosis