Pre-heparin Lipoprotein Lipase Mass

Physical Activity Attenuates the Obesity-Induced Dysregulated Expression of Brown Adipokines in Murine Interscapular Brown Adipose Tissue

In recent years, brown adipose tissue (BAT), which has a high heat-producing capacity, has been confirmed to exist even in adults, and it has become a focal point for the prevention and the improvement of obesity and lifestyle-related diseases. However, the influences of obesity and physical activity (PA) on the fluid factors secreted from BAT (brown adipokines) are not well understood. In this study, therefore, we focused on brown adipokines and investigated the effects of obesity and PA. The abnormal expressions of gene fluid factors such as galectin-3 (Lgals3) and Lgals3 binding protein (Lgals3bp), whose proteins are secreted from HB2 brown adipocytes, were observed in the interscapular BAT of obese mice fed a high-fat diet for 4 months. PA attenuated the abnormalities in the expressions of these genes. Furthermore, although the gene expressions of factors related to brown adipocyte differentiation such as peroxisome proliferator-activated receptor gamma coactivator 1-α were also down-regulated in the BAT of the obese mice, PA suppressed the down-regulation of these factors. On the other hand, lipogenesis was increased more in HB2 cells overexpressing Lgals3 compared with that in control cells, and the overexpression of Lgals3bp decreased the mitochondrial mass. These results indicate that PA attenuates the obesity-induced dysregulated expression of brown adipokines and suggests that Lgals3 and Lgals3bp are involved in brown adipocyte differentiation.

Severe hypertriglyceridemia in a subject with disturbed life style and poor glycemic control without recurrence of acute pancreatitis: a case report

BACKGROUND

Hypertriglyceridemia is often observed as the result of lipid abnormality and frequently associated with other lipid and metabolic disorders. Aggravation of hypertriglyceridemia is caused by various conditions. However, severe hypertriglyceridemia is usually induced by an addition of some secondary clinical conditions such as uncontrolled type 2 diabetes mellitus (T2DM) and obesity with insulin resistance.

CASE PRESENTATION

A 40-year-old man with 4-year history of dyslipidemia and T2DM visited after his interruption of therapy for about 1.5 years. His past history was acute pancreatitis. His life style was markedly disturbed, and he had a lot of risk factors for hypertriglyceridemia. Surprisingly, his serum triglyceride level was as high as 16,900 mg/dL. His aggravation and remission of hypertriglyceridemia were closely associated with the alteration of RLP-cholesterol levels in dyslipidemia and glycoalbumin and ketone body levels in T2DM.

CONCLUSION

We report very severe hypertriglyceridemia, which seemed to be caused by markedly disturbed life style and poorly controlled T2DM. Total therapy with diet and drug for each disease is very important for the improvement of very severe hypertriglyceridemia. This case report suggests that very severe hypertriglyceridemia alone does not necessarily bring out acute pancreatitis, although it is very important to check pancreatitis markers in such a situation.

Role of lipoprotein lipase in lipid metabolism

PURPOSE OF REVIEW

A major step in energy metabolism is hydrolysis of triacylglycerol-rich lipoproteins (TRLs) to release fatty acids that can be used or stored. This is accomplished by lipoprotein lipase (LPL) at 'binding lipolysis sites' at the vascular endothelium. A multitude of interactions are involved in this seemingly simple reaction. Recent advances in the understanding of some of these factors will be discussed in an attempt to build a comprehensive picture.

RECENT FINDINGS

The first event in catabolism of TRLs is that they dock at the vascular endothelium. This requires LPL and GPIHBP1, the endothelial transporter of LPL.Kinetic studies in rats with labeled chylomicrons showed that once a chylomicron has docked in the heart it stays for minutes and a large number of triacylglycerol molecules are split. The distribution of binding between tissues reflects the amount of LPL, as evident from studies with mutant mice.Clearance of TRLs is often slowed down in metabolic disease, as was demonstrated both in mice and men. In mice, this was directly connected to decreased amounts of endothelial LPL.

SUMMARY

The LPL system is central in energy metabolism and results from interplay between several factors. Rapid and exciting progress is being made.

Relationships among serum lipoprotein lipase mass, visceral fat, and retinal nerve fiber layer thickness

PURPOSE

The purpose of the study was to determine whether there were significant correlations among the serum lipoprotein lipase mass, visceral fat, and the retinal nerve fiber layer (RNFL) thickness.

METHODS

We studied 118 consecutive subjects. Optical coherence tomography (OCT) was used to measure the RNFL thickness. The Pearson correlation coefficient was used to determine the relationships among lipoprotein lipase (LPL) mass, visceral fat area by computed tomography, OCT, and other parameters. We performed a multiple regression analysis to identify independent factors for the RNFL sectors that were the most strongly correlated with the LPL mass and visceral fat area.

RESULTS

The LPL mass was significantly correlated with the nasal RNFL thickness in both eyes (right eye: r = 0.24, p = 0.008, left eye: 0.32, 0.0008) and inferior RNFL thickness in the left eye ( r = 0.23, p = 0.01). The visceral fat area was significantly correlated with the nasal RNFL thickness in both eyes (right eye: r = -0.19, p = 0.04, left eye: -0.30, 0.0008) and the inferior RNFL thickness in the left eye ( r = -0.23, p = 0.01). The subcutaneous fat area was not significantly correlated with any OCT parameters. The multiple regression analysis revealed that age, LPL mass, and visceral fat area were independent contributors to the nasal RNFL thickness in the left eye (age, standard regression coefficient = -0.34 , p = 0.0004; LPL mass, 0.26, 2.49, 0.01; visceral fat area, -0.21, 0.03).

CONCLUSION

A reduction of lipoprotein lipase and accumulation of visceral fat might produce retinal neurodegenerative disorders that decrease the RNFL thickness, especially on the nasal side.

The Relationship between Preheparin Lipoprotein Lipase and Metabolic Derangements in Obese Japanese Children

The aim of this study was to clarify the relationship between preheparin lipoprotein lipase (LPL) and derangements of metabolic status in obese Japanese children. We examined 102 obese children (55 boys and 47 girls; mean age 10.9 yr). Anthropometry, blood pressure and levels of liver transaminases, serum lipids and lipoproteins, uric acid, fasting blood glucose (FBG), serum insulin, LPL, leptin and adiponectin were measured. The subjects were divided into the metabolic syndrome (MS) and non-MS groups. The levels of LPL were compared between these groups. Statistical analysis showed that the LPL levels were significantly lower in the MS group compared with the non-MS group, with the levels decreasing progressively as the number of MS components increased. We conclude that LPL levels decrease also in obese Japanese children with a deteriorated metabolic status in the same way as in adults.

Preheparin lipoprotein lipase mass is a practical marker of insulin resistance in ambulatory type 2 diabetic patients treated with oral hypoglycemic agents

BACKGROUND

Lipoprotein lipase (LPL) is a key enzyme in the metabolism of triglyceride (TG)-rich lipoproteins. LPL in the preheparin serum (Pr-LPL) mass reflects the insulin sensitivity of diabetic patients (DM) receiving neither insulin nor hypoglycemic agents.

METHODS

To determine whether Pr-LPL mass is a marker of insulin resistance in ambulatory type 2 DM receiving oral hypoglycemic agents, we measured Pr-LPL mass using an enzyme immunoassay in 107 ambulatory DM aged 64.9+/-11.5 y.

RESULTS

Pr-LPL mass was inversely correlated with the homeostasis model assessment of insulin resistance (HOMA-IR) (-0.363, p<0.001), insulin (-0.351, p<0.001), and lnTG (-0.402, p<0.001), and was positively correlated with HDL-C (0.471, p<0.001). The correlation between Pr-LPL mass and HOMA-IR was equally strong in men and women. Despite medications, hypertension, dyslipidemia, and metabolic syndrome were associated with low Pr-LPL mass. Multiple regression analysis revealed that HOMA-IR was the strongest predictor of Pr-LPL mass. Pr-LPL mass remained constant from 07:30 to 17:30 h.

CONCLUSIONS

Pr-LPL mass is a marker of insulin resistance in ambulatory type 2 DM receiving oral hypoglycemic agents, and Pr-LPL mass is stable during the daytime. Therefore, Pr-LPL mass may be more useful than HOMA-IR at diabetes clinics, especially for patients in the postprandial state.

Endothelial lipase concentrations are increased in metabolic syndrome and associated with coronary atherosclerosis

BACKGROUND

Endothelial lipase (EL), a new member of the lipase family, has been shown to modulate high-density lipoprotein (HDL-C) metabolism and atherosclerosis in mouse models. We hypothesized that EL concentrations would be associated with decreased HDL-C and increased atherosclerosis in humans.

METHODS AND FINDINGS

Healthy individuals with a family history of premature coronary heart disease (n = 858) were recruited as part of the Study of the Inherited Risk of Atherosclerosis. Blood was drawn in the fasting state before and, in a subgroup (n = 510), after administration of a single dose of intravenous heparin. Plasma lipids were measured enzymatically, lipoprotein subclasses were assessed by nuclear magnetic resonance, and coronary artery calcification (CAC) was quantified by electron beam computed tomography. Plasma EL mass was measured using a newly developed enzyme-linked immunosorbent assay. Median EL mass in pre-heparin plasma was 442 (interquartile range = 324-617) ng/ml. Median post-heparin mass was approximately 3-fold higher, 1,313 (888-1,927) ng/ml. The correlation between pre-heparin EL mass and post-heparin EL mass was 0.46 (p < 0.001). EL mass concentrations in both pre- and post-heparin plasma significantly correlated with all NCEP ATPIII-defined metabolic syndrome factors: waist circumference (r = 0.28 and 0.22, respectively, p < 0.001 for each), blood pressure (r = 0.18 and 0.24, p < 0.001 for each), triglycerides (r = 0.22, p < 0.001; and 0.13, p = 0.004), HDL cholesterol (r = -0.11, p = 0.002; and -0.18, p < 0.001), and fasting glucose (r = 0.11 and 0.16, p = 0.001 for both). EL mass in both routine (odds ratio [OR] = 1.67, p = 0.01) and post-heparin (OR = 2.42, p = 0.003) plasma was associated with CAC as determined by ordinal regression after adjustment for age, gender, waist circumference, vasoactive medications, hormone replacement therapy (women), and established cardiovascular risk factors.

CONCLUSIONS

We report, to our knowledge for the first time, that human plasma EL concentrations, in both post-heparin and routine pre-heparin plasma, are significantly associated with metabolic syndrome features and with subclinical atherosclerosis. EL may be a pro-atherogenic factor in humans, especially in overweight individuals and those with metabolic syndrome.

Changes in lipoprotein lipase modulate tissue energy supply during stress

We studied the variations caused by stress in lipoprotein lipase (LPL) activity, LPL-mRNA, and local blood flow in LPL-rich tissues in the rat. Stress was produced by body immobilization (Immo): the rat's limbs were taped to metal mounts, and its head was placed in a plastic tube. Chronic stress (2 h daily of Immo) decreased total LPL activity in mesenteric and epididymal white adipose tissue (WAT) and was accompanied by a weight reduction of these tissues. In limb muscle, heart, and adrenals, total LPL activity and mRNA levels increased, and, in plasma, LPL activity and mass also increased. Acute stress (30-min Immo) caused a decrease in total LPL activity only in retroperitoneal WAT and an increase in preheparin plasma active LPL, but the overall weight of this tissue did not vary significantly. We propose an early release of the enzyme from this tissue into the bloodstream by some unknown extracellular pathways or other local mechanisms. These changes in this key energy-regulating enzyme are probably induced by catecholamines. They modify the flow of energy substrates between tissues, switching the WAT from importer to exporter of free fatty acids and favoring the uptake by muscle of circulating triacylglycerides for energy supply. Moreover, we found that acute stress almost doubled blood flow in all WAT studied, favoring the export of free fatty acids.