Comparison of two diets of varying glycemic index on carotid subclinical atherosclerosis in obese children

Childhood obesity is associated with an increased carotid intima-media thickness (IMT) and stiffness. Increased carotid wall thickening and rigidity are considered markers of subclinical atherosclerosis. The aim of the present study was to test the effect of two hypocaloric diets of varying glycemic index on weight loss and markers of subclinical atherosclerosis in obese children. Seventy consecutive obese children attending the Outpatient Weight Clinic of the Department of Pediatrics were invited to participate in an intensive dietary protocol. Twenty-six accepted and were randomly assigned to two different groups: the first group followed a hypocaloric low-glycemic index diet and the second a hypocaloric high-glycemic index diet. Anthropometric measures and biochemical tests were performed in all children. Quantitative B-mode ultrasound scans were used to measure intima-media thickness (IMT) and diameters of the common carotid artery. Considering both groups together, at 6 months, body mass index decreased from 28.3 ± 3.1 to 25.8 ± 3.3 kg/m², systolic blood pressure from 119 ± 12 to 110 ± 11 mmHg (P< 0.001), diastolic blood pressure from 78 ± 8 to 74 ± 7 mmHg (P< 0.001), IMT from 0.48 ± 0.05 to 0.43 ± 0.07 mm (P< 0.001), stiffness from 3.57 ± 1.04 to 2.98 ± 0.94 mm (P = 0.002), and high-sensitivity C-reactive protein from 1.5 ± 0.9 (values log transformed) to 0.4 ± 1.1 (P < 0.001). No differences were detectable in fasting serum triglycerides, total cholesterol, and high-density lipoprotein cholesterol. Insulin resistance (calculated by the HOmeostatic Model Assessment index [HOMA] score) significantly reduced only in the low-glycemic-index diet group (P < 0.04). In conclusion, this study confirms a benefit of hypocaloric diets on carotid IMT and stiffness in obese children and demonstrates, for the first time, an amelioration of insulin sensitivity in obese children after a low-glycemic index diet. These results justify the advice to obese children to follow a low-glycemic index diet in order to improve their cardiometabolic profile.     

Carotid artery wall hypertrophy in children with metabolic syndrome

Preclinical vascular changes (increased stiffness and/or wall thickness) have been observed in children with known metabolic risk factors. Aim of the present study was to evaluate different carotid parameters, representative of vascular health, in children with and without metabolic syndrome (MS). We studied 38 children with MS (mean age 9.6+/-2.6 years; range 6-14 years) and 45 healthy age-matched subjects. Children who met three or more of the following criteria qualified as having the MS: fasting glucose >110 mg dl(-1), fasting triglyceride concentration >100 mg dl(-1), fasting high-density lipoprotein cholesterol concentration <50 mg dl(-1) for females or <45 mg dl(-1) for the males, waist circumference >75th percentile for age and gender and systolic or diastolic blood pressure >90th percentile for age, gender and height. Carotid B-mode ultrasound examinations were performed and intima-media thickness and diameters were measured in all subjects. Arterial geometry was further characterized by calculation of carotid cross-sectional area. Carotid intima-media thickness and lumen diameters were increased in children with MS as compared to children without MS. Moreover, carotid cross-sectional area was significantly higher in the group of children with MS 9.83+/-1.86 mm(2) [mean+/-s.d.] compared with the control group: 7.77+/-1.72 mm(2), P<0.001, even after adjustment for age, gender and height. Carotid hypertrophy is already detectable in children with MS. High-resolution B-mode ultrasound could provide a valuable tool for the cardiovascular risk stratification of children.     

HIV-1 matrix protein p17 increases the production of proinflammatory cytokines and counteracts IL-4 activity by binding to a cellular receptor

Purified recombinant HIV-1 p17 matrix protein significantly increased HIV-1 replication in preactivated peripheral blood mononuclear cell cultures obtained from healthy donors. Because HIV-1 infection and replication is related to cell activation and differentiation status, in the present study, we investigated the role played by p17 during the process of T cell stimulation. Using freshly isolated peripheral blood mononuclear cells, we demonstrate that p17 was able to enhance levels of tumor necrosis factor alpha and IFN-gamma released from cells stimulated by IL-2. IL-4 was found to down-regulate IFN-gamma and tumor necrosis factor alpha, and p17 restored the ability of cells to produce both cytokines. The property of p17 to increase production of proinflammatory cytokines could be a mechanism exploited by the virus to create a more suitable environment for HIV-1 infection and replication. Our data show that p17 exerts its biological activity after binding to a specific cellular receptor expressed on activated T lymphocytes. The functional p17 epitope involved in receptor binding was found to be located at the NH(2)-terminal region of viral protein. Immunization of BALB/c mice with a 14-aa synthetic peptide representative of the HIV-1 p17 functional region (SGGELDRWEKIRLR) resulted in the development of p17 neutralizing antibodies capable of blocking the interaction between p17 and its cellular receptor. Our results define a role for p17 in HIV-1 pathogenesis and contribute to our understanding of the molecular mechanism of HIV-1 infection and the development of additional antiviral therapeutic strategies.