Relationship of Insulin Sensitivity and Left Ventricular Mass in Uncomplicated Obesity

Objective: We studied uncomplicated obesity as a model to evaluate the influence of insulin sensitivity per se on left ventricular mass (LVM) and geometry. Research Methods and Procedures: We selected 50 obese subjects (BMI > 30 kg/m²; 38 women and 12 men; mean age, 38.4 ± 10 years; BMI, 36.4 ± 10.5 kg/m²) with normal blood pressure, glucose tolerance, and plasmatic lipid levels. Thirty lean subjects formed the control group. Each subject underwent euglycemic insulin clamp (7 pmol/min per kg) to evaluate whole body glucose use (M index) and echocardiogram to calculate LVM and indexed LVM. Results: Insulin‐resistant obese subjects had higher LVM, LVM/h^2.7, LVM/body surface area, and LVM/fat‐free mass_kg (p = 0.001; p = <0.001 p = 0.001, and p = 0.04, respectively) than obese subjects with normal insulin sensitivity. Multivariate regression analysis showed that M index was the strongest independent correlate of LVM (r² = 0.34; p = 0.03). Discussion: Our findings showed that insulin resistance, in uncomplicated obesity, is associated with an increased LVM and precocious changes of left ventricular geometry, whereas preserved insulin sensitivity is not associated with increased LVM.     

Homo- and hetero-bivalent edrophonium-like ammonium salts as highly potent, dual binding site AChE inhibitors

A number of mono- and bis-quaternary ammonium salts, containing edrophonium-like and coumarin moieties tethered by an appropriate linker, proved to be highly potent and selective dual binding site acetylcholinesterase inhibitors with good selectivity over butyrylcholinesterase. Homobivalent bis-quaternary inhibitors 11 and 12, differing by only one methylene unit in the linker, were the most potent and selective inhibitors exhibiting a sub-nanomolar affinity (IC(50)=0.49 and 0.17 nM, respectively) and a high butyryl-/acetylcholinesterase affinity ratio (SI=1465 and 4165, respectively). The corresponding hetero-bivalent coumarinic inhibitors 13 and 14 were also endowed with excellent inhibitory potency but a lower AChE selectivity (IC(50)=2.1 and 1.0 nM, and SI=505 and 708, respectively). Docking simulations enabled clear interpretation of the structure-affinity relationships and detection of key binding interactions at the primary and peripheral AChE binding sites.     

Simulated microgravity impairs aldosterone secretion in rats: possible involvement of adrenomedullin

The prolonged exposure to microgravity (MG) or simulated MG (SMG) has been reported to cause hypotension, mainly due to reduced vascular contractility, and dysregulation of fluid and electrolyte balance. However, the mechanism(s) involved in these MG- or SMG-induced effects is not yet completely elucidated. Hence, we investigated in the rat the effect of prolonged (15 day) SMG, in the form of hindlimb unweighting, on the renin-angiotensin-aldosterone system (RAAS), as well as on atrial natriuretic peptide (ANP) and adrenomedullin (ADM), two hypotensive peptides that play a major role in the regulation of RAAS activity by inhibiting adrenal aldosterone secretion. SMG caused a mild hypotension in rats, associated with the blockade of body weight gain. Plasma aldosterone concentration and basal and agonist-stimulated in vitro aldosterone secretion from adrenal slices were decreased, and plasma renin activity was moderately increased. Neither Na(+) and K(+) serum concentrations nor ACTH and corticosterone blood levels were significantly affected. Plasma ANP concentration did not display significant alterations, while ADM blood concentration underwent a marked rise. The administration of the ADM-receptor antagonist ADM-(22-52) during the last 3 days of hindlimb unweighting reversed the SMG-induced hypotension and hypoaldosteronism. Collectively, these findings allow us to suggest that prolonged SMG impairs RAAS activity in rats, through a mechanism probably involving upregulation of the ADM system. Both hypoaldosteronism and increased ADM secretion may contribute to the development of hypotension during prolonged exposure to SMG.     

Tissue distribution of pneumadin immunoreactivity in the rat

Pneumadin (PNM) is a decapeptide, originally isolated from mammalian lungs, which exerts a potent stimulating effect on arginine-vasopressin (AVP) release, thereby evoking an antidiuretic effect. We have established a specific radioimmunoassay (RIA) method for rat PNM determination, the sensitivity of which is sufficient for measuring tissue content of the peptide. Moreover, raised antibodies have been used for the immunocytochemical detection of PNM in several rat organs. As expected, high concentrations of PNM were detected by RIA in newborn and adult rat lungs and immunocytochemistry (ICC) localized PNM immunoreactivity (IR) in the bronchial and bronchiolar epithelium. Very high concentrations of PNM were measured by RIA in the prostate, and ICC showed that PNM-IR is contained in the epithelial cells. RIA and ICC demonstrated the presence of low amounts of PNM in the thymus. The highest content of radioimmunoassayable PNM was found in the kidneys and intestinal tract, but dilution test suggested the presence of some interfering substances in these tissues. Accordingly, ICC-detectable PNM-IR was absent in the kidneys and present only in the duodenal criptae and Brunner's glands of the intestinal tract. RIA did not measure sizeable PNM concentrations in the thyroid gland, but ICC showed PNM-IR in C-cells. RIA and ICC did not detected PNM in testes, seminal vesicles, ovaries, uterus, pancreas, liver, spleen, adrenal glands, and heart. Taken together, our findings suggest that PNM, in addition to its role as hypothalamo-pituitary AVP secretagogue, may be involved in the autocrine-paracrine functional regulation of other peripheral organs, like lungs and prostate and perhaps duodenum, thymus and thyroid gland.     

Pneumadin in the ventral prostate and seminal vesicles of estradiol-treated rats: RIA and immunocytochemical studies

Pneumadin (PNM) is a decapeptide (the rat peptide: Tyr-Gly-Glu-Pro-Lys-Leu-Asp-Ala-Gly-Val-NH2) isolated from mammalian lungs. Human and rat PNM differ only by substitution of one amino acid--Tyr/Ala. PNM evokes an antidiuretic effect via a potent stimulation of arginine-vasopressin (AVP) release. By means of recently established, highly specific RIA method, high concentration of PNM had been found in the rat ventral prostate. Castration resulted in a profound drop in PNM concentration, an effect prevented by testosterone replacement. The present studies were aimed at investigating the effect of prolonged estradiol administration on PNM concentration, content and localization in the prostate and seminal vesicles of the rat. Depo estradiol (estradiolum valerianicum) administration to adult male rats resulted in a notable atrophy of ventral prostate and seminal vesicles. During the entire experiment (till day 30 after administration), PNM concentration in ventral prostate was similar to that seen in intact animals, while peptide content per gland was markedly lowered. PNM immunostaining was observed in prostate epithelium of estradiol-treated rats and its localization resembled that observed in intact animals. Nearly 40 times lower PNM concentration than in ventral prostate was found in seminal vesicles. In contrast to prostate, on days 20 and 30 of estradiol treatment PNM concentration in seminal vesicles was higher than in intact rats. However, due to profound seminal vesicle atrophy, PNM content per entire gland was notably lowered in estradiol-injected rats. By immunocytochemistry, PNM-immunoreactive substances were not found in seminal vesicles of either intact or estradiol-administered rats. High PNM concentration in the rat prostate suggests its important role in the function of the gland.     

The elusive diploic veins: anthropological and anatomical perspective

Diploic veins (Canales diploicae), which were identified in dogs by Dupuytren more than 200 years ago (Hecker [1845] Die anatomische Verhaltnisse und Krankheiten der Venae diploicae und Vasa emissaria. Erfahrungen und Abhandlungen im Gebiete der Chirurgie und Augenheilkunde. Erlangen), have remained inadequately understood and scantily referenced in the anatomical and anthropological literature. The tunnels formed by diploic veins are among the few known skeletal markers of soft tissue alteration. Protected by two bony laminae, diploic vein tunnels often resist postdepositional destruction and may provide a new way to assess living and extinct hominid populations. This basic research was carried out to enable future utilization of the diploic venous channels in anthropologic research. In the present study, diploic venous channels were observed radiographically in 108 human adults aged 19 years and above, 18 infants and children aged 1-18 years (Hamann-Todd Osteological Collection), eight fetuses aged 7-9 months (the Johns Hopkins Collection), and seven nonhuman primates (Hamann-Todd Osteological Collection). In addition, seven documented cases of parents and children were radiographed for genetic evaluation (Osteological Collection of The Hungarian Natural History Museum). Five distinct diploic distribution patterns were identified and described in this study. This was at variance with the impressions reported in dissection-based studies. Independence of diploic vein pattern from demographic (gender and age) and size factors and their tendency to be symmetrical make them amenable and reliable traits for skeletal population study. Diploic vein patterns appeared to be more complicated in humans than in nonhuman primates, raising the possibility of future phylogenetic applications.     

Antiproliferative effects of antisense oligonucleotides directed to the RNA of c-myc oncogene.

Several groups have reported the use of antisense oligonucleotides to inhibit c-myc gene expression and study its biological role. However high concentrations of free oligonucleotides were generally needed. To lower their concentration and stabilize the antisense effect against c-myc, oligonucleotides were covalently linked to poly(L-lysine) and administered in ternary complexes formed with heparin (100 micrograms/ml). A sequence specific growth inhibition was observed at concentrations lower than 1 microM, while oligonucleotide-poly(L-lysine) conjugates alone were inefficient. Similar results occurred with other polyanionic compounds. Inhibition of proliferation was correlated to a reduction of c-myc protein and to a transient decrease in c-myc mRNA level. However, implication of RNase H in this process could not be demonstrated.     

WASP integrates substrate topology and cell polarity to guide neutrophil migration

To control their movement, cells need to coordinate actin assembly with the geometric features of their substrate. Here, we uncover a role for the actin regulator WASP in the 3D migration of neutrophils. We show that WASP responds to substrate topology by enriching to sites of inward, substrate-induced membrane deformation. Superresolution imaging reveals that WASP preferentially enriches to the necks of these substrate-induced invaginations, a distribution that could support substrate pinching. WASP facilitates recruitment of the Arp2/3 complex to these sites, stimulating local actin assembly that couples substrate features with the cytoskeleton. Surprisingly, WASP only enriches to membrane deformations in the front half of the cell, within a permissive zone set by WASP’s front-biased regulator Cdc42. While WASP KO cells exhibit relatively normal migration on flat substrates, they are defective at topology-directed migration. Our data suggest that WASP integrates substrate topology with cell polarity by selectively polymerizing actin around substrate-induced membrane deformations in the front half of the cell.     

Evidence for G-quadruplex in the promoter of vegfr-2 and its targeting to inhibit tumor angiogenesis

Tumor angiogenesis is mainly mediated by vascular endothelial growth factor (VEGF), a pro-angiogenic factor produced by cancer cells and active on the endothelium through the VEGF receptor 2 (VEGFR-2). Here we identify a G-rich sequence within the proximal promoter region of vegfr-2, able to form an antiparallel G-quadruplex (G4) structure. This G4 structure can be efficiently stabilized by small molecules with the consequent inhibition of vegfr-2 expression. Functionally, the G4-mediated reduction of VEGFR-2 protein causes a switching off of signaling components that, converging on actin cytoskeleton, regulate the cellular events leading to endothelial cell proliferation, migration and differentiation. As a result of endothelial cell function impairment, angiogenic process is strongly inhibited by G4 ligands both in vitro and in vivo. Interestingly, the G4-mediated antiangiogenic effect seems to recapitulate that observed by using a specific interference RNA against vegfr-2, and it is strongly antagonized by overexpressing the vegfr-2 gene. In conclusion, we describe the evidence for the existence of G4 in the promoter of vegfr-2, whose expression and function can be markedly inhibited by G4 ligands, thereby revealing a new, and so far undescribed, way to block VEGFR-2 as target for anticancer therapy.