Evaluation of serum glycated lipoprotein(a) levels in noninsulin-dependent diabetic patients

Investigating the Atherogenic Risk of Lipoprotein(a) in Type 2 Diabetic Patients

Type 2 diabetes mellitus (T2DM) has high morbidity and results in increased risk of mortality mainly due to cardiovascular diseases. Different factors have been found to be responsible for the increased prevalence of coronary artery disease (CAD) in T2DM. One of these factors includes raised serum levels of lipoprotein(a) (Lp(a)). The present study was designed to evaluate the association of Lp(a) levels with T2DM in Libyan patients and find the degree of association between Lp(a), glycemic control, insulin, and lipid profile. The study included 100 T2DM patients, recruited from the Benghazi Center for Diagnosis and Treatment of Diabetes, and 30 apparently healthy age and sex-matched individuals, to serve as controls. All participants completed a questionnaire to obtain clinical information and medical history. Blood samples were collected and analyzed for Lp(a), fasting blood glucose (FBS), HbA1c, insulin, total cholesterol (TC), triglycerides (TAG), low-density lipoprotein c (LDL-c), and high-density lipoprotein c (HDL-c). The results from the comparison between the control and experimental groups showed that Lp(a) was significantly higher in diabetic patients. It showed the positive correlation with TC and LDL-c. On the contrary, it showed no significant correlations with glycemic control parameters nor insulin, TAG, HDL-c, body mass index (BMI), and blood pressor (BP). Cardiovascular disease (CVD) risk in type 2 diabetic patients could be dependent on risk factors other than LDL-c, which may not be an independent risk factor for the development and progression of atherogenesis in T2DM. Lp(a) may be a new metabolic syndrome risk factor, and it may be useful as a cardiovascular risk biomarker in future clinical practice.

Nonenzymatic Post-Translational Modification Derived Products: New Biomarkers of Protein Aging

During their biological life, proteins are exposed in a cumulative way to irreversible nonenzymatic post-translational modifications that are responsible for their molecular aging and generate specific by-products called »post-translational modification derived products« (PTMDPs). PTMDPs are involved in the pathogenesis of various diseases such as diabetes mellitus, renal insufficiency and atherosclerosis, and are potential biomarkers in clinical practice. Nonenzymatic glycation refers to the spontaneous binding of glucose and reducing sugars to free amino groups and is amplified by oxidative processes (referred to as »glycoxidation«). It generates many reactive by-products such as aldehydes and leads to the formation of »advanced glycation end products« (AGEs). AGEs accumulatein vivo, alter tissue organization and activate membrane receptors such as RAGE, which triggers inflammatory responses. Carbamylation is due to the binding of isocyanic acid, formedin vivoeither by spontaneous dissociation of urea or by action of myeloperoxidase on thiocyanate, and generates homocitrulline from lysine groups. Carbamylation leads to alteration of the structural and biological properties of proteins, and favors inflammation and atherosclerosis. PTMDPs may be assayed by different methods, among others LC-MS/MS or immuno assays, constitute a promising field of investigation in basic research and are potential major biomarkers in laboratory medicine.

Evaluation of nonenzymatic posttranslational modification-derived products as biomarkers of molecular aging of proteins

BACKGROUND

During their biological life, proteins are exposed in a cumulative fashion to irreversible nonenzymatic, late posttranslational modifications that are responsible for their molecular aging. It is now well established that these damaged proteins constitute a molecular substratum for many dysfunctions described in metabolic and age-related diseases, such as diabetes mellitus, renal insufficiency, atherosclerosis, or neurodegenerative diseases. Accordingly, the specific end products derived from these reactions are considered potentially useful biomarkers for these diseases.

CONTENT

The aim of this review is to give an overview of nonenzymatic posttranslational modifications of proteins and their influence in vivo, take inventory of the analytical methods available for the measurement of posttranslational modification-derived products, and assess the potential contribution of new technologies for their clinical use as biological markers of protein molecular aging.

SUMMARY

Despite their clinical relevance, biomarkers of posttranslational modifications of proteins have been studied only in the context of experimental clinical research, owing to the analytical complexity of their measurement. The recent implementation in clinical chemistry laboratories of mass spectrometry-based methods that provide higher specificity and sensitivity has facilitated the measurement of these compounds. These markers are not used currently by clinicians in routine practice, however, and many challenges, such as standardization, have to be confronted before these markers can be used as efficient tools in the detection and monitoring of long-term complications of metabolic and age-related diseases.

Lipids and lipoprotein(a) concentrations in Pakistani patients with type 2 diabetes mellitus

AIM

The aim of the present study was to analyze serum lipoprotein(a) [Lp(a)] levels in Pakistani patients with type 2 diabetes mellitus (DM) and to find correlations between clinical characteristics and dyslipidaemias in these patients.

METHODS

Fasting blood samples were analyzed for Lp(a), total cholesterol, triglycerides, low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), glucose and glycosylated haemoglobin (HbA1c) in 68 Pakistani patients with type 2 DM and 40 non-diabetic healthy control subjects.

RESULTS

Lp(a) levels were significantly raised in diabetics as compared to the control group. No correlation of Lp(a) was seen with age, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP) and fasting glucose. There was a positive correlation of BMI to SBP and DBP. There was a significant positive correlation between Lp(a) and total cholesterol and LDL-c. No correlation of Lp(a) was observed with HDL-c, triglycerides and glycosylated haemoglobin (HbA1c).

CONCLUSION

The present study led us to conclude that serum Lp(a) levels are significantly raised in type 2 DM and have a positive correlation with serum total and LDL-c levels.