Unrecognized diabetes and myocardial necrosis: predictors of hyperglycemia in myocardial infarction

BACKGROUND

Hyperglycemia in the acute phase of myocardial infarction is an important prognostic factor. However, its pathophysiology is not fully understood.

OBJECTIVE

To analyze simultaneously the correlation between hyperglycemia and biochemical markers related to stress, glucose and lipid metabolism, coagulation, inflammation, and myocardial necrosis. METHODS Eighty patients with acute myocardial infarction were prospectively included. The following parameters were analyzed: blood glucose; stress hormones (cortisol and norepinephrine); glucose metabolism factors [glycated hemoglobin (HbA1c); insulin]; lipoproteins (total cholesterol, LDL, HDL, minimally modified electronegative LDL, and adiponectin); glycerides (triglycerides, VLDL and fatty acids); coagulation factors (factor VII, fibrinogen, plasminogen activator inhibitor-1); inflammation (high-sensitivity C reactive protein); and myocardial necrosis (CK-MB and troponin). Continuous variables were converted into degrees of relevance using fuzzy logic.

RESULTS

Significant correlation was observed between hyperglycemia and glucose metabolism (p < 0.001), lipoproteins (p = 0.03), and necrosis factors (p = 0.03). In the multivariate analysis, only glucose metabolism (OR = 4.3; CI = 2.1-68.9; and p < 0.001) and myocardial necrosis (OR = 22.5; CI = 2-253; and p = 0.012) showed independent and significant correlation. For the analysis of the influence of history of diabetes mellitus, a regression model including only patients without diabetes mellitus was developed, and the results did not change. Finally, in the model adjusted for age, gender, and clinical variables (history of diabetes mellitus, hypertension and dyslipidemia), three variables maintained a significant and independent association with hyperglycemia: glucose metabolism (OR = 24.1; CI = 4.8-122.1; and p < 0.001), myocardial necrosis (OR = 21.9; CI = 1.3-360.9; and p = 0.03), and history of DM (OR = 27; CI = 3.7-195.7; and p = 0.001).

CONCLUSION

Glucose metabolism and myocardial necrosis markers were the best predictors of hyperglycemia in patients with acute myocardial infarction.

Metabolism of triglyceride-rich lipoproteins and transfer of lipids to high-density lipoproteins (HDL) in vegan and omnivore subjects

BACKGROUND AND AIMS

Vegan diet excludes all foodstuffs of animal origin and leads to cholesterol lowering and possibly reduction of cardiovascular disease risk. The aim was to investigate whether vegan diet improves the metabolic pathway of triglyceride-rich lipoproteins, consisting in lipoprotein lipolysis and removal from circulation of the resulting remnants and to verify whether the diet alters HDL metabolism by changing lipid transfers to this lipoprotein.

METHODS AND RESULTS

21 vegan and 29 omnivores eutrophic and normolipidemic subjects were intravenously injected triglyceride-rich emulsions labeled with (14)C-cholesterol oleate and (3)H-triolein: fractional clearance rates (FCR, in min(-1)) were calculated from samples collected during 60 min for radioactive counting. Lipid transfer to HDL was assayed by incubating plasma samples with a donor nanoemulsion labeled with radioactive lipids; % lipids transferred to HDL were quantified in supernatant after chemical precipitation of non-HDL fractions and nanoemulsion. Serum LDL cholesterol was lower in vegans than in omnivores (2.1 ± 0.8, 2.7 ± 0.7 mmol/L, respectively, p < 0,05), but HDL cholesterol and triglycerides were equal. Cholesteryl ester FCR was greater in vegans than in omnivores (0.016 ± 0.012, 0.003 ± 0.003, p < 0.01), whereas triglyceride FCR was equal (0.024 ± 0.014, 0.030 ± 0.016, N.S.). Cholesteryl ester transfer to HDL was lower in vegans than in omnivores (2.7 ± 0.6, 3.5 ± 1.5%, p < 0,05). Free-cholesterol, triglyceride and phospholipid transfer were equal, as well as HDL size.

CONCLUSION

Remnant removal from circulation, estimated by cholesteryl oleate FCR was faster in vegans, but the lipolysis process, estimated by triglyceride FCR was equal. Increased removal of atherogenic remnants and diminution of cholesteryl ester transfer may favor atherosclerosis prevention by vegan diet.

Effect of neoadjuvant chemotherapy on low-density lipoprotein (LDL) receptor and LDL receptor-related protein 1 (LRP-1) receptor in locally advanced breast cancer

Low-density lipoprotein (LDL) receptors are overexpressed in most neoplastic cell lines and provide a mechanism for the internalization and concentration of drug-laden nanoemulsions that bind to these receptors. The aim of the present study was to determine whether the administration of standard chemotherapeutic schemes can alter the expression of LDL and LDL receptor-related protein 1 (LRP-1) receptors in breast carcinoma. Fragments of tumoral and normal breast tissue from 16 consecutive volunteer women with breast cancer in stage II or III were obtained from biopsies before the beginning of neoadjuvant chemotherapy and after chemotherapy, from fragments excised during mastectomy. Tissues were analyzed by immunohistochemistry for both receptors. Because complete response to treatment was achieved in 4 patients, only the tumors from 12 were analyzed. Before chemotherapy, there was overexpression of LDL receptor in the tumoral tissue compared to normal breast tissue in 8 of these patients. LRP-1 receptor overexpression was observed in tumors of 4 patients. After chemotherapy, expression of both receptors decreased in the tumors of 6 patients, increased in 4 and was unchanged in 2. Nonetheless, even when chemotherapy reduced receptors expression, the expression was still above normal. The fact that chemotherapy does not impair LDL receptors expression supports the use of drug carrier systems that target neoplastic cells by the LDL receptor endocytic pathway in patients on conventional chemotherapy.

Efeitos do treinamento resistido na lipoproteína de baixa densidade

Os benefícios da prática regular do exercício físico estão claramente estabelecidos na literatura. Entretanto, a escolha do tipo de exercício ideal pode ser mais salutar para indivíduos com doenças específicas e patologias associadas. O propósito desta revisão foi verificar se o treinamento resistido (TR) exerce alguma alteração no colesterol da lipoproteína de baixa densidade (LDL-C). Foram observadas grandes diferenças na literatura, dificultando uma conclusão em relação aos benefícios do TR nesta revisão. No entanto, foi visto que o TR pode ser promissor na redução dos níveis de LDL-C, principalmente em homens e mulheres adultos, em pacientes com diabetes mellitus tipo 1 e tipo 2 e em mulheres pré-menopausa, não mostrando diferenças na população idosa. Os autores concluem que o TR é uma boa opção de exercício físico para indivíduos, principalmente quando o treinamento aeróbio (TA) é contraindicado.

Metabolism of a lipid nanoemulsion resembling low-density lipoprotein in patients with grade iii obesity

INTRODUCTION

Obesity increases triglyceride levels and decreases high-density lipoprotein concentrations in plasma. Artificial emulsions resembling lipidic plasma lipoprotein structures have been used to evaluate low-density lipoprotein metabolism. In grade III obesity, low density lipoprotein metabolism is poorly understood.

OBJECTIVE

To evaluate the kinetics with which a cholesterol-rich emulsion (called a low-density emulsion) binds to low-density lipoprotein receptors in a group of patients with grade III obesity by the fractional clearance rate.

METHODS

A low-density emulsion was labeled with [(14)C]-cholesterol ester and [(3)H]-triglycerides and injected intravenously into ten normolipidemic non-diabetic patients with grade III obesity [body mass index higher than 40 kg/m(2)] and into ten non-obese healthy controls. Blood samples were collected over 24 hours to determine the plasma decay curve and to calculate the fractional clearance rate.

RESULTS

There was no difference regarding plasma levels of total cholesterol or low-density lipoprotein cholesterol between the two groups. The fractional clearance rate of triglycerides was 0.086 +/- 0.044 in the obese group and 0.122 +/- 0.026 in the controls (p = 0.040), and the fractional clearance rate of cholesterol ester (h(-1)) was 0.052 +/- 0.021 in the obese subjects and 0.058 +/- 0.015 (p = 0.971) in the controls.

CONCLUSION

Grade III obese subjects exhibited normal low-density lipoprotein removal from plasma as tested by the nanoemulsion method, but triglyceride removal was slower.

Plasma kinetics of chylomicron-like emulsion in renal transplant patients receiving cyclosporin-based immunosuppression

BACKGROUND

Atherosclerotic cardiovascular disease is prevalent among renal transplant patients. Increase in serum total cholesterol, low-density lipoprotein, and very low-density lipoprotein is common in those patients. Alterations in chylomicron metabolism, however, are also related to atherogenesis and were not studied in renal transplant.

HYPOTHESIS

The aim of this study was to evaluate chylomicron metabolism in renal transplant recipients receiving cyclosporin-based immunosuppression. We determined the plasma kinetics of triglyceride-rich emulsions labeled with [3H]triolein and [14C]cholesteryl oleate that are known to mimic the chylomicron metabolism when injected into the blood stream.

METHODS

Fourteen renal transplant recipients with normal renal function (10 men, 4 women, aged 40 +/- 6.1 years) and 17 age- and gender-matched healthy controls received bolus injections of the chylomicron-like emulsion. Plasma samples were then taken at regular intervals during 60 min. Disappearance curves of the labels and the respective fractional clearance rates (FCR) were calculated in order to measure lipolysis and chylomicron remnant removal from the plasma.

RESULTS

Fasting serum lipid levels did not differ in the two groups. The difference between Median FCR of [3H]triolein emulsion in renal transplant patients and that obtained in the controls (0.07 vs. 0.11 min-1, NS) was not statistically significant. Median FCR of [14C]cholesteryl oleate also did not differ between the groups (patients: 0.044; controls: 0.046, NS).

CONCLUSION

These results indicate that neither chylomicron lipolysis nor remnant removal are affected in stable renal transplant patients treated with cyclosporin-based immunosuppression.

Transferência de lípides para a lipoproteína de alta densidade (HDl) em mulheres com diabetes melito tipo 1

INTRODUÇÃO: Os portadores de diabetes melito tipo 1 (DM1) possuem aumentado risco de doença cardiovascular e, ainda assim, podem apresentar perfil lipídico normal. Para esclarecer se os níveis normais de HDL podem ocultar defeitos na função, foram estudados a transferência de lípides para a HDL em DM1. MÉTODOS: Vinte e uma mulheres jovens portadoras de DM1 foram comparadas com 21 mulheres não-diabéticas. Nanoemulsões foram usadas como doadoras de lípides para HDL: uma marcada com ³H-triglicérides e 14C-colesterol livre e outra com ³H-éster de colesterol e 14C-fosfolípides. Após 1 hora de incubação com amostras de plasma, seguida por precipitação química, o sobrenadante, contendo HDL, teve a radioatividade contada. RESULTADOS: Nenhuma diferença foi encontrada nas transferências dos ésteres de colesterol, triglicérides, colesterol livre e fosfolípides para as HDL. CONCLUSÃO: A transferência de lípides para a HDL não está afetada em portadoras de DM1. Isso sugere que a doença não altera a composição de lipoproteínas e a ação de proteínas de transferência.

Alterations in lipid transfer to High-Density Lipoprotein (HDL) and activity of paraoxonase-1 in HIV+ patients

HIV+ patients often develop alterations of the plasma lipids that may implicate in development of premature coronary artery disease. High-density lipoprotein (HDL) has an important role in preventing atherogenesis and the aim of this study was to investigate aspects of HDL function in HIV+ patients. HIV+ patients (n = 48) and healthy control subjects (n = 45) of both sexes with similar age were studied. Twenty-five were not being treated with antiretroviral agents, 13 were under reverse transcriptase inhibitor nucleosidic and non-nucleosidic (NRTI+NNRTI) and 10 were under NRTI + protease inhibitors (NRTI+PI) treatment. Paraoxonase 1 (PON1) activity and the transfer of free and esterified cholesterol, tryglicerides and phospholipids from a lipidic nanoemulsion to HDL were analyzed. In comparison with healthy controls, HIV+ patients presented low PON-1 activity and diminished transfer of free cholesterol and tryglicerides. In contrast, phospholipid transfer was increased in those patients, whereas the transfer of cholesteryl esters was unchanged. NRTI+NNRTI increases the transfer of cholesteryl esters and triglycerides but in NRTI+PI there was no difference in respect to non-treated HIV+ patients. HDL from HIV+ patients has smaller antioxidant properties, as shown by lower PON-1 activity, and the transfer of lipids to this lipoprotein fraction is also altered, suggesting that HDL function is defective in those patients.

Lipolysis of emulsion models of triglyceride-rich lipoproteins is altered in male patients with abdominal aorta aneurysm

Disorders of the lipid metabolism may play a role in the genesis of abdominal aorta aneurysm. The present study examined the intravascular catabolism of chylomicrons, the lipoproteins that carry the dietary lipids absorbed by the intestine in the circulation in patients with abdominal aorta aneurysm. Thirteen male patients (72 +/- 5 years) with abdominal aorta aneurysm with normal plasma lipid profile and 13 healthy male control subjects (73 +/- 5 years) participated in the study. The method of chylomicron-like emulsions was used to evaluate this metabolism. The emulsion labeled with 14C-cholesteryl oleate and (3)H-triolein was injected intravenously in both groups. Blood samples were taken at regular intervals over 60 min to determine the decay curves. The fractional clearance rate (FCR) of the radioactive labels was calculated by compartmental analysis. The FCR of the emulsion with (3)H-triolein was smaller in the aortic aneurysm patients than in controls (0.025 +/- 0.017 vs 0.039 +/- 0.019 min-1; P < 0.05), but the FCR of 14C-cholesteryl oleate of both groups did not differ. In conclusion, as indicated by the triglyceride FCR, chylomicron lipolysis is diminished in male patients with aortic aneurysm, whereas the remnant removal which is traced by the cholesteryl oleate FCR is not altered. The results suggest that defects in the chylomicron metabolism may represent a risk factor for development of abdominal aortic aneurysm.

Chloroquine increases low-density lipoprotein removal from plasma in systemic lupus patients

Low-density lipoprotein (LDL) pathway in systemic lupus erythematosus (SLE) patients taking chloroquine diphosphate (CDP) was evaluated through the kinetic behavior of a radioactive cholesterol-rich nanoemulsion (LDE) that resembles the LDL lipidic structure. LDE was labeled with (14)C-cholesteryl ester ((14)C-CE), then IV injected in inactive female SLE patients: 10 taking CDP (CDP), 10 without therapy (NO THERAPY); and 10 normal subjects (CONTROL). Groups were age-matched and followed rigorous selection criteria of conditions that interfere in the lipid profile. Blood samples were collected in pre-established intervals after infusion for radioactivity measurement. Fasting lipoproteins were determined in the beginning of kinetic studies. Fractional clearance rate (FCR) of (14)C-CE was significantly different in the three groups (P = 0.03). In fact, a greater FCR of (14)C-CE was observed in CDP compared to NO THERAPY (0.076 +/- 0.037 versus 0.046 +/- 0.021 h(-1); P < 0.05) and to CONTROL (0.0516 +/- 0.0125 h(-1); P < 0.05). Accordingly, a significant lower total and LDL cholesterol were observed in CDP (156 +/- 16 and 88 +/- 16 mg/dl) compared to NO THERAPY (174 +/- 15 and 108 +/- 17 mg/dl; P < 0.05) and to CONTROL (200 +/- 24 and 118 +/- 23 mg/dl; P < 0.05). In contrast, no difference in (FCR) of (14)C-CE of NO THERAPY and CONTROL groups was observed. This is the first in vivo demonstration that LDE removal by LDL receptor from plasma is increased in SLE patients taking CDP with a consequent beneficial decrease in LDL-c levels.

[Aortic stenosis and coronary disease. Analysis of risk factors]

OBJECTIVE

To analyze clinical laboratorial aspects of the presence of coronary disease in patients with aortic stenosis and evaluate the influence of risk factors in the development of obstructive coronary disease.

METHODS

We studied 65 patients who had severe aortic stenosis with an indication for surgery, ages 51 to 85 years, 40 of them women. The coronary angiography assessment resulted in two groups: 26 (40%) with obstructive coronary disease and 39 (60%) with no coronary artery lesion. Personal antecedents for coronary disease (smoking, dyslipidemia, diabetes mellitus, arterial hypertension, family antecedents, sedentarism, and alcoholism) were analyzed. Additionally, the following assessments were made: electrocardiogram, echocardiogram with Doppler, and laboratory tests (blood glucose, total cholesterol and fractions, triglycerides, Apo-A1 and B, fibrinogen, lipoprotein (a) and fraction of triglycerides and cholesterol removal in both groups.

RESULTS

In the age analysis, the group with obstructive coronary disease belonged to an older age range with statistical significance (p<0.0001). Signs of ischemia of the anterior wall identified on the electrocardiogram showed a significant relationship with the obstruction of an anterior interventricular artery (p<0.002). The univariate analysis showed a significant difference between the groups regarding averages of the aortic (p= 0.041), HDL (p=0.042), and fibrinogen (p=0.047) gradients. The group with coronary disease presented an average gradient and HDL level lower than the group without obstructive coronary disease. For the fibrinogen variable, the average in the group with no coronary disease was lower compared to that of the coronariopathy group. The multivariate logistic regression analysis showed fibrinogen levels as an independent variable for coronary disease (p<0.039).

CONCLUSION

Fibrinogen was an independent risk factor for the association between obstructive coronary disease and aortic stenosis.

Relationships in women between body mass index and the intravascular metabolism of chylomicron-like emulsions

OBJECTIVE

To investigate whether increasing body mass index (BMI) produces increasingly intense disturbances in the metabolism of chylomicrons, the lipoproteins that carry the dietary lipids absorbed by the intestine in the circulation.

SUBJECTS

Four groups of 10 normolipidemic nondiabetic women at the normal (BMI<25 kg/m(2)), preobese (BMI 25-30), obese (BMI 30-40) and morbid obese (BMI>40).

METHODS

Chylomicron metabolism was studied using the method of triglyceride-rich emulsions that mimic chylomicrons. The chylomicron-like emulsion doubly labeled with (3)H-triolein (TO) and (14)C-cholesteryl-oleate (CO) was intravenously injected to calculate the plasma fractional clearance rates (FCR, in min(-1)) by a compartmental analysis model. FCR-TO mirrors both the lipolysis from lipoprotein lipase that the emulsion suffers while still in the circulation, and the triglycerides portion that is not broken down and is removed from the plasma together with the remnant particles. Lipolysis index is calculated subtracting CO from TO areas under the curve.

RESULTS

FCR-TO did not differ among the four groups. The lipolysis index was positively correlated with BMI (r=0.310; P=0.05). On the other hand, FCR-CO progressively diminished from the normal to the morbid obese group (0.069+/-0.01; 0.064+/-0.01; 0.031+/-0.003; 0.029+/-0.005 min(-1), respectively, P=0.003) and there was a negative correlation between FCR-CO and BMI (r=-0.388; P=0.01).

CONCLUSION

In obesity, the capacity to break down chylomicron triglycerides by lipoprotein lipase in vivo increases, but the ability of the organism to remove the resulting chylomicron remnants particles progressively diminishes as the BMI rises. Remnant accumulation most likely predisposes to coronary artery disease development.

Cellular cholesterol efflux mediated by HDL isolated from subjects with low HDL levels and coronary artery disease

OBJECTIVE

The aim of this study was to verify whether HDL particles isolated from patients with coronary artery disease (CAD) and low HDL-C had diminished ability to promote cholesterol efflux from cultured cells compared with HDL isolated from subjects without CAD and with normal HDL-C.

METHODS

Smooth muscle cells isolated from human aortas cultured and radiolabeled with H-cholesterol were loaded with cholesterol and incubated with increasing concentrations of HDL isolated from 13 CAD patients with low HDL-C (CAD group) or from 5 controls without CAD (C group). Efflux of cellular cholesterol was measured by cellular depletion of radiolabeled cholesterol and by the appearance of H-cholesterol into experimental medium expressed as a percentage of total labeled cholesterol.

RESULTS

Cholesterol efflux increased with the amount of HDL present in the medium, and no difference was found between groups at various HDL protein concentrations: efflux was 28 +/- 6.3% (C) and 25.5 +/- 8.9% (CAD) with 25 microg/mL; 34 +/- 4.3% (C) and 31.9 +/- 6.6% (CD) with 50 micro g/mL and 39.5 +/- 3.5% (C) and 37.1 +/- 4.4% (CAD) with 100 micro g/mL, HDL.

CONCLUSION

Because the HDL fraction of CAD patients with low HDL-C have normal ability to extract cholesterol from cells of the vessel wall, it is suggested that low HDL-C atherogenicity should be ascribed to diminished concentrations of HDL particles rather than to the qualitative properties of the HDL fraction.

Plasma kinetics of a chylomicron-like emulsion in normolipidemic obese women after a short-period weight loss by energy-restricted diet

Chylomicrons carry dietary fats in the bloodstream for storage in body tissues, and thus play an important role in obesity. The 2-step chylomicron metabolism consists of lipolysis by lipoprotein lipase (LPL) on vessel walls and hepatic uptake of triglyceride-depleted remnants. A triglyceride-rich emulsion that mimics chylomicrons, labeled with [9,10-(3)H]glycerol-trioleate (TG) and [1-(14)C] cholesteryl-oleate (CE) was intravenously injected into 14 obese women with body mass index between 30 and 40 kg/m(2) (age, 30 to 40 years), before and after a 2-month energy-restricted diet and into non-obese controls for determination of radioactive lipid plasma kinetics. TG kinetics evaluates lipolysis, whereas CE kinetics evaluates remnant removal. The emulsion TG fractional clearance rate (FCR, in min(-1)) was similar in obese women and their controls (0.126 +/- 0.065; controls, 0.111 +/- 0.031), but the CE-FCR was pronouncedly reduced in the obese subjects (0.028 +/- 0.014; controls, 0.070 +/- 0.009 min(-1); P <.0001). After the energy-restricted diet, TG-FCR was reduced in the obese women (0.075 +/- 0.044 min(-1); P <.05), but CE-FCR was unchanged (0.032 +/- 0.025 min(-1)). Therefore, the lipolysis of the chylomicron-like emulsion is normal in obese women, but remnant removal from the plasma is diminished. After active weight loss by an energy-restricted diet, the remnant removal was unchanged but lipolysis was diminished, possibly due to adaptative changes in LPL activity.

Plasma kinetics of a cholesterol-rich emulsion in young, middle-aged, and elderly subjects

Low density lipoprotein (LDL) plasma concentration is increased in the elderly. In this group, the incidence of coronary artery disease (CAD) is greater and LDL remains an important risk factor for CAD development. In this study, the plasma kinetics of a cholesterol-rich emulsion that binds to LDL receptors was studied in 10-subject groups of the elderly (70 +/- 4 yr), middle-aged (42 +/- 5 yr) and young (23 +/- 2 yr). All were normolipidemic, nonobese, nondiabetic subjects who did not have CAD. The emulsion was labeled with 14C-cholesteryl oleate and injected intravenously into the subjects. Blood samples were drawn at regular intervals over 24 h to determine the plasma decay curve of the emulsion radioactive label and to estimate its plasma fractional clearance rate (FCR, in h(-1)). FCR of the emulsion label was smaller in elderly compared to young subjects (0.032 +/- 0.035 and 0.071 +/- 0.049 h(-1), respectively; mean +/- SD, P< 0.05). FCR of the middle-aged subjects (0.050 +/- 0.071 h(-1)) was intermediate between the values of the elderly and young subjects, although not statistically different from them. A negative correlation was found betweeen the emulsion FCR and subjects' age (r = -0.47, P = 0.008). We conclude that aging is accompanied by progressively diminished clearance of the emulsion cholesterol esters and, by analogy, of the native LDL.