The associations between abdominal visceral fat and the plasma hemostatic system were examined in 38-year-old healthy men (n=52) with a wide range of fatness and fat distribution. Plasma hemostatic factors and metabolic parameters, including glucose tolerance, were measured, and body fatness and adipose tissue distribution were assessed by using computed tomography. The men with more visceral fat (ie, higher than the median value [n=26]) had a less favorable metabolic profile than the men with less visceral fat (n=26). They also had significantly (P<.05) higher plasma fibrinogen, factor VIII clotting activity, tissue-type plasminogen activator antigen, and plasminogen activator inhibitor-1 (PAI-1) activity (19.2+/-2.4 versus 8.5+/-1.6 AU/mL, P<.001) and lower basal tissue-type plasminogen activator activity. After adjustment for plasma insulin, the men with larger abdominal visceral fat area still had significantly higher plasma PAI-1 activity, but no difference was found in any of the other hemostatic factors. In multiple linear regression analysis, abdominal visceral fat area was a positive predictor of plasma PAI-1 activity, but it failed to show any significant association with other hemostatic factors after controlling for plasma insulin. These results suggest the presence of relationships between abdominal visceral fat and several plasma hemostatic factors that are largely mediated by concomitant alterations in plasma insulin concentration. In addition, our results suggest that abdominal accumulation of visceral fat is an independent predictor of plasma PAI-1 activity.

SummaryThe relationship between liver steatosis, evaluated by ultrasonography, and various plasma haemostatic factors was examined in 64 apparently healthy males, aged 38 years. Plasma levels of factor VII clotting activity (F-VIIc), plasminogen activator inhibitor-1 (PAI-1) activity and antigen, tissue-type plasminogen activator (t-PA) activity significantly differed in men with liver steatosis (n = 31) as compared with those without steatosis (n = 33). No significant differences were found in t-PA antigen and F-VII antigen. The men with liver steatosis also had significantly higher body mass index (BMI), plasma triglyceride and 2 h post-load insulin concentrations. While the differences in plasma haemostatic factors were substantially unchanged after adjustment for BMI, they totally disappeared when further allowance was made for plasma triglyceride and 2 h insulin concentrations. In conclusion, these results indicate that liver steatosis correlates specifically with increased PAI-1, F-VIIc and decreased t-PA levels, and suggest that such a relation is largely mediated by concomitant alterations in plasma triglyceride and insulin concentrations.

Translocator protein 18 kDa (TSPO) is a promising target for molecular imaging and for targeted drug delivery to tumors overexpressing TSPO. In our previous work, new macromolecular conjugates with a high affinity and selectivity for TSPO were prepared by conjugating the biodegradable poly(d,l-lactic-co-glycolic acid) (PLGA) polymer with two potent and selective TSPO ligands, namely, compounds 1 and 2. Based on this, nanoparticle delivery systems (NPs), employing TSPO ligand-PLGA conjugated (PLGA-TSPO) polymers, were prepared. Furthermore, to evaluate the ability of the new NPs to be used as a drug delivery systems for anticancer therapy, PLGA-TSPO NPs were loaded with 5-fluorouracil (5-FU), chosen as a model hydrophilic anticancer drug. The main goal of this work was to investigate the synergistic potential of using NP conjugates PLGA-TSPO, TSPO ligands being pro-apoptotic agents, to simultaneously deliver a cytotoxic anticancer drug. To better highlight the occurrence of synergistic effects, dual drug loaded PLGA NPs (PLGA NPs/5-FU/1) and dual drug loaded PLGA-TSPO NPs (PLGA-TSPO NPs/5-FU/1), with 5-FU and TSPO ligand 1 physically incorporated together, were also prepared and characterized. The particle size and size distribution, surface morphology, and drug encapsulation efficiency, as well as the drug release kinetics, were investigated. In vitro cytotoxicity studies were carried out on C6 glioma cells overexpressing TSPO, and to evaluate the potential uptake of these nanoparticulate systems, the internalization of fluorescent labeled PLGA-TSPO NPs (FITC-PLGA-TSPO NPs) was also investigated by fluorescence microscopy. Results demonstrated that PLGA-TSPO NPs/5-FU and dual drug loaded PLGA NPs/5-FU/1 and PLGA-TSPO NPs/5-FU/1 could significantly enhance toxicity against human cancer cells due to the synergistic effect of the TSPO ligand 1 with the anticancer drug 5-FU.

Context The hyperinsulinism/hyperammonemia (HI/HA) syndrome, the second most common form of congenital hyperinsulinism, has been associated to dominant mutations in GLUD1, coding for the mitochondrial enzyme glutamate dehydrogenase, that increase enzyme activity by reducing its sensitivity to allosteric inhibition by GTP. Objective To identify the underlying genetic aetiology in two siblings who presented with the biochemical features of HI/HA syndrome but did not carry pathogenic variants in GLUD1, and to determine the functional impact of the newly identified mutation. Main Outcome Measures The patients were investigated by whole exome sequencing. Yeast complementation studies and biochemical assays on the recombinant mutated protein were performed. The consequences of stable slc25a36 silencing in HeLa cells were also investigated. Results A homozygous splice site variant was identified in solute carrier family 25, member 36 (SLC25A36), encoding the pyrimidine nucleotide carrier 2 (PNC2), a mitochondrial nucleotide carrier that transports pyrimidine as well as guanine nucleotides across the inner mitochondrial membrane. The mutation leads to a 26 aa in-frame deletion in the first repeat domain of the protein which abolished transport activity. Furthermore, knockdown of slc25a36 expression in HeLa cells caused a marked reduction in the mitochondrial GTP content which likely leads to an hyperactivation of glutamate dehydrogenase in our patients. Conclusions We report for the first time a mutation in PNC2/SLC25A36 leading to HI/HA and provide functional evidence of the molecular mechanism responsible for this phenotype. Our findings underscore the importance of mitochondrial nucleotide metabolism and expand the role of mitochondrial transporters in insulin secretion.

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