Lucas José de Campos Machado

FTIR and UV‒vis study of chemically engineered biomaterial surfaces for protein immobilization

The biomaterials research field has broadened in the last 3 decades, including replacement of diseased or damaged parts, assist in healing, correct and improve functional abnormality, drug delivery systems, immunological kits and biosensors. Proteins play crucial role in almost every biological system. They are involved in enzymatic catalysis, transport and storage, coordinated motion, mechanical support, immune protection, control of growth and cell differentiation among many others. The immobilization of proteins onto surface functionalized substrates has been one of the most promising areas in bioengineering field. It is important to note that the term immobilization can refer either to a temporary or to a permanent localization of the biomolecule on or within a support. Proteins have very particular chain configurations and conformations that promote high levels of specificity during chemical interactions. In the present work, we aimed to study the phenomenon of protein immobilization onto biomaterial with chemically engineered surface. We have tailored the surface of the porous gels of SiO2 with 5 different silane surface modifying agents: tetraethoxysilane (TEOS), 3‒mercaptopropyltrimethoxysilane (MPTMS) and 3‒aminopropyltriethoxysilane (APTES), 3‒glycidoxypropyltrimethoxysilane (GPTMS) and 3‒isocyanatopropyltriethoxysilane (ICPES). Fourier Transform Infrared Spectroscopy (FTIR) was used to characterize the presence of all specific chemical groups in the materials. The surface functionalized gels were then immersed in porcine insulin (PI) solutions for protein immobilization. The incorporation of protein within the gels was also monitored by FTIR spectroscopy. The kinetics of protein adsorption and desorption from the gel matrix in vitro tests were monitored by UV‒visible spectroscopy. We could not observe any evidence of denaturation of insulin after its desorption from gel matrices using UV‒visible spectroscopy technique. In vivo tests with adult male rats were used to verify the immobilized insulin bioactivity after implantation of different biomaterial with functionalized surfaces. Plasma glucose levels were obtained by using the Glucose GOD‒ANA Colorimetric Assay. All surface modified materials have presented acute hypoglycemic peak response associated with the insulin bioactivity.

The pregnancy-induced increase of plasma angiotensin-(1-7) is blunted in gestational diabetes

BACKGROUND AND OBJECTIVE It has been shown that the circulating Renin-Angiotensin System (RAS) is activated during normal pregnancy, but little is known about RAS in pregnancies complicated by gestational diabetes (GDM). GDM is considered not merely a temporary condition, but a harbinger of hypertension and type 2 diabetes. The aim of this study was to evaluate the circulating RAS profile in normotensive women with GDM at the third trimester of pregnancy and to compare the results with healthy pregnant and non-pregnant age-matched women. METHODS The diagnostic criteria for GDM followed the recommendations of the American Diabetes Association. Angiotensin I (Ang I), Angiotensin II (Ang II) and Angiotensin 1-7 [Ang-(1-7)] were determined in 24 pregnant patients with GDM; 12 healthy pregnant women and 12 non-pregnant women by radioimmunoassay. RESULTS Levels of Ang I, Ang II and Ang-(1-7) were higher in pregnant women (p<0.05), but showed a different pattern in the GDM group, in which reduced Ang-(1-7) circulating levels were found (p<0.05). This observation was confirmed by the significantly lower Ang-(1-7)/Ang I ratio (p<0.05). CONCLUSION Our data suggest that reduced levels of the vasodilator Ang-(1-7) could be implicated in the endothelial dysfunction seen in gestational diabetic women during and after pregnancy.

High-sensitivity C-reactive protein levels in HIV-infected patients treated or not with antiretroviral drugs and their correlation with factors related to cardiovascular risk and HIV infection

AIMS To compare high-sensitivity C-reactive protein (hsCRP) in HIV-infected patients treated or not with antiretroviral (ARV) drugs and to correlate hsCRP levels with traditional cardiovascular risk factors and parameters of HIV infection. METHODS One hundred and seventy-one HIV-infected patients were included (129 ARV-treated and 42 ARV-naïve). Evaluations included anthropometric measurements, blood pressure, laboratory tests, ultrasonographic measurement of fat thickness and impedance analysis. RESULTS hsCRP levels were higher in ARV-treated compared to ARV-naïve patients (p<0.001). Seventy-two (56%) ARV-treated patients and 11 (26%) ARV-naïve patients had hsCRP concentrations >3 mg/dl (high risk for cardiovascular complications) (OR 3.56; 95%CI: 1.55-8.29; p=0.001, chi(2) test). hsCRP levels correlated positively with waist measurement (p=0.004), waist-to-hip ratio (p<0.001), systolic (p=0.05) and diastolic (p=0.03) blood pressure, intra-abdominal fat thickness (p=0.02), triglycerides (p=0.001), total cholesterol (p=0.01), fasting glucose (p=0.01), and glucose (p<0.001) and insulin levels (p=0.02) measured 2 h after load. No correlation was found between hsCRP levels and CD4 cell counts and HIV-viral load. Independent factors associated with hsCRP levels were therapy with current non-nucleoside reverse transcriptase inhibitors (NNRTI) (p=0.003), waist-to-hip ratio (p=0.006), fasting glucose (p=0.049) and glucose levels 2 h after load (p=0.003) in multivariate analysis model 1 and current NNRTI therapy (p<0.001), protease inhibitor therapy (p=0.016) and cardiometabolic syndrome (p=0.022) in multivariate analysis model 2. CONCLUSION hsCRP in HIV-infected patients is associated with traditional cardiovascular risk factors, principally in ARV-treated patients. hsCRP levels are not associated with CD4 cell counts and HIV-viral load and may constitute a marker for cardiovascular risk related to HIV infection and ARV therapy.

Distribuição da gordura corporal e perfis lipídico e glicêmico de pacientes infectados pelo HIV

The aims of this study were to describe anthropometric data and glycemic and lipidic profiles of HIV-infected patients treated or not with antiretrovirals (ARV) drugs, and to assess association between these drugs and body composition changes, lipid and glucose homeostasis disturbances. There were 176 patients included (133 ARV-treated patients and 43 ARV-naïve). The patients were submitted to clinical evaluation, laboratorial analysis, ultrasonographic measurements, bioelectrical impedance analysis and skin folds thickness measurements. The ARV-treated group showed higher waist-to-hip ratio (p= 0.0002), higher intra-abdominal fat thickness measured by ultrasonography (p= 0.003) and lower bicipital (p= 0.01) and tricipital (p= 0.0002) skin folds. This group also showed higher triglyceride (p= 0.0002), total cholesterol (p= 0.00007), HDL cholesterol (p= 0.009), glucose measurements one hour (p= 0.01) and two hours (p= 0.001) after dextrose load, higher levels of fasting insulin (p= 0.03) and higher HOMAR index (p= 0.02). The antiretroviral drugs are associated with increased visceral fat and decreased peripheral fat pads. Beside that, these drugs are associated with atherogenic lipid profile and insulin resistance, two independent risk predictors of cardiovascular disease.

Ultrasonographic measurement of intra-abdominal fat thickness in HIV-infected patients treated or not with antiretroviral drugs and its correlation to lipid and glycemic profiles.

Aims: To compare the intra-abdominal fat thickness measured by ultrasound between HIV-infected patients treated or not with antiretroviral drugs and to correlate these visceral adiposity measurements to other parameters of cardiovascular risks. Methods: In a transversal observational study, 160 HIV-infected patients were recruited and divided in two groups, i.e., 123 antiretroviral (ARV)-treated and 37 ARV-naïve patients. These patients were submitted to anthropometric determinations, laboratorial analysis, ultrasonographic measurements of subcutaneous and intra- abdominal fat thickness and to tetrapolar bioelectrical impedance analysis in order to measure the body composition. Results: In the patients treated with highly active antiretroviral therapy (HAART) the intra-abdominal fat pad was significantly thicker than that of the untreated group (69 ± 21 mm, n = 123 vs. 60 ± 18 mm, n = 37; p = 0.03 Student’s t test). The intra-abdominal fat thickness correlated significantly with plasma triglyceride, total cholesterol, fasting glucose, glucose measurements 2 h after dextrose load, fasting insulin, HOMA-IR index, systolic and diastolic blood pressures, weight, BMI, WHR and caliper-measured total fat percentage. Conclusion: The results showed that antiretroviral therapy is associated with increased ultrasonographic measurements of visceral adiposity. Our data demonstrated a strong correlation between intra-abdominal fat thickness and independent risk factors of cardiovascular disease: atherogenic lipid profile and insulin resistance.

Hyperglycemic action of angiotensin II in freely moving rats

Angiotensin II has been implicated in the regulation of liver glycogen phosphorylase. Although it has been suggested that angiotensin II can raise blood glucose levels during hemorrhage, experimental data have not been presented. In the present study, the effect of angiotensin II on blood glucose levels was studied in freely moving rats, divided in three experimental groups: 1) intravenous administration of angiotensin II (0.48, 1.9, or 4.8 nmol) caused a dose-dependence response; 2) intracerebroventricular administration of angiotensin II (1.9 or 4.8 nmol) did not cause any significant change in glycemia compared with saline-treated controls; 3) intravenous administration of [Sar1,Thr8]angiotensin II, an antagonist of angiotensin II (750 ng/100 g b. wt. as a bolus plus a continuous injection of 25 ng/100 g b. wt./min over 30 min), greatly attenuated (39.2% lower than controls; p < 0.01) the hyperglycemic response to hemorrhage (1.2 ml/100 g b.wt.). These data indicate an in vivo involvement of angiotensin II in blood glucose regulation.

Effect of [1-Sar,8-Thr]-angiotensin II on the hyperglycemic response to hemorrhage in adrenodemedullated and guanethidine-treated rats

The present experiments were designed to further investigate the action of an angiotensin II antagonist on the hyperglycemic response to hemorrhage (1.2 ml/100 g b.wt./2 min). The animals were divided into 3 experimental groups; (1) sham-operated animals submitted to intravenous administration of [1-Sar,8-Thr]-angiotensin II (sarthran), an antagonist of angiotensin II (750 ng/100 g b.wt. as a bolus plus an infusion of 25 ng/100 g b.wt./min over 30 min), which greatly attenuated (51.8% lower than controls; P < 0.01) the hyperglycemic response to hemorrhage; (2) animals submitted to adrenodemedullation which decreased the hyperglycemic response to hemorrhage by 64% (P < 0.01). However, sarthran infusion into adrenodemedullated rats caused a 38.5% further decrease in hyperglycemic response to hemorrhage (P < 0.01); and (3) intact animals submitted to blockade of sympathetic noradrenergic pathways by treatment with guanethidine (10 mg/100 g b.wt.), which greatly decreased the baseline value of plasma glucose (64.1 +/- 3.5 mg% vs. 125.3 +/- 4.5 mg%, P < 0.01), and reduced the hyperglycemic response to hemorrhage by 34% (P < 0.01). Sarthran infusion into guanethidine-treated rats caused a further 34% decrease in hyperglycemic response to hemorrhage (P < 0.01). These data indicate that angiotensin II has a direct hyperglycemic effect in addition to its action on sympathetic nervous system activation and adrenomedullary secretion.

Left ventricle diastolic dysfunction in diabetes: an update

Diabetes mellitus, a disease that has been reaching epidemic proportions, is an important risk factor to the development of cardiovascular complication. Diabetes causes changes within the cardiac structure and function, even in the absence of atherosclerotic disease. The left ventricular diastolic dysfunction (VE) represents the earliest pre-clinical manifestation of diabetic cardiomyopathy, preceding the systolic dysfunction and being able to evolve to symptomatic heart failure. The doppler echocardiography has emerged as an important noninvasive diagnostic tool, providing reliable data in the stages of diastolic function, as well as for systolic function. With the advent of recent echocardiographic techniques, such as tissue Doppler and color M-mode, the accuracy in identifying the moderate diastolic dysfunction, the pseudonormal pattern, has significantly improved. Due to cardio-metabolic repercussions of DM, a detailed evaluation of cardiovascular function in diabetic patients is important, and some alterations may be seen even in patients with gestational diabetes.

Metabolic long-term follow-up of functioning simultaneous pancreas-kidney transplantation versus pancreas transplantation alone: insights and limitations.

Background. Pancreas transplantation involves a set of procedures that, in some cases, lead to different complications and outcomes. The aim of this study was to analyze the long-term effects of pancreas transplantation regarding carbohydrate and lipid metabolism parameters to determine differences between simultaneous pancreas-kidney (SPK) transplantation and pancreas transplantation alone (PTA). Methods. Sixty-four patients (46 SPK and 18 PTA), with an immunosuppression protocol based on tacrolimus plus mycophenolate mofetil and prednisone, were evaluated for at least 1 year after transplantation. No patient made use of any hypoglycemic or hypolipidemic drugs. Comparisons were performed between SPK and PTA patients using the chi-square test, Fischers exact test, and unpaired Students t test, as appropriate. Results. Patients were 39.8±9.3 years old, predominantly male (60.9%), with a mean follow-up of 25.4±10.4 months after transplantation. The PTA group exhibited worse renal function and higher tacrolimus levels than the SPK group. Fasting glucose, 2 hr plasma glucose after overload, C-peptide, and HbA1C were within the normal range, with no statistically significant differences between the PTA and SPK groups. Insulin (INS) and the homeostasis model assessment of INS resistance index were above the normal range in both the groups. Lipids were also similar between groups. Conclusions. The majority of patients with long-term functioning pancreas transplant achieved good glucose control without use of exogenous INS or oral antidiabetic drugs, although they were hyperinsulinemic. There were no significant differences concerning glucose and lipid parameters between the SPK and PTA groups, even though the PTA patients exhibited higher tacrolimus levels and worse renal function.

The impact of functioning pancreas-kidney transplantation and pancreas alone transplantation on the lipid metabolism of statin-naive diabetic patients

Abstract: Objective:  To compare the lipid profile (total cholesterol – TC, triglycerides – TG, high density lipoprotein cholesterol – HDL‐c, low density lipoprotein cholesterol – LDL‐c and non‐HDL cholesterol – NHDL‐c) of patients with functioning pancreas–kidney transplantation (PKT) or pancreas transplantation alone (PTA) after one (T1) and two yr (T2) following their pre‐transplantation data (T0).