Role of alpha adrenoceptors and nitric oxide on cardiovascular responses in acute and chronic hypertension

The contribution of α-adrenoceptors and nitric oxide (NO) on the alterations of sympathetically mediated cardiovascular responses after acute (AcH) and chronic (ChH) hypertension was evaluated in pithed aortic coarcted hypertensive rats. Pressor and tachycardia response produced by electrical stimulation of preganglionic sympathetic fibers or exogenous noradrenaline (NA) were recorded in the absence and presence of prazosin (α₁-antagonist), rauwolscine (α₂-antagonist), or N ^G-nitro-l-arginine methyl ester (l-NAME; an inhibitor of NO synthase). Compared with age-matched sham-operated rats (Nt), the pressor response produced by electrical stimulation or NA was smaller in AcH rats and larger in ChH rats. Prazosin caused a decrease of pressor response elicited by electrical stimulation or NA in all groups. However, this effect was higher in ChH. Rauwolscine produced a similar increase of sympathetically mediated pressor response in Nt and AcH rats. Nevertheless, this antagonist did not affect the sympathetically mediated pressor response in ChH rats. In addition, rauwolscine did not affect the NA-induced pressor response in all groups. The pressor response elicited by l-NAME was larger in all groups compared without l-NAME and in presence of l-arginine. Moreover, l-NAME in the presence of NA increased sympathetically mediated pressor response is in all groups, compared without it or in the presence of l-arginine. Compared with Nt, basally produced NO in aortic rings was increased in AcH but decreased in ChH. Collectively, our data suggest that decreased cardiovascular reactivity in AcH is due to an increase in basally produced NO. In ChH, enhanced cardiovascular response appears to be associated with a decrease in produced NO and an increase in released NA from sympathetic nerves.     

Kinetics on Demand Is a Simple Mathematical Solution that Fits Recorded Caffeine-Induced Luminal SR Ca2+ Changes in Smooth Muscle Cells

The process of Ca²⁺ release from sarcoplasmic reticulum (SR) comprises 4 phases in smooth muscle cells. Phase 1 is characterized by a large increase of the intracellular Ca²⁺ concentration ([Ca²⁺]_i) with a minimal reduction of the free luminal SR [Ca²⁺] ([Ca²⁺]_FSR). Importantly, active SR Ca²⁺ ATPases (SERCA pumps) are necessary for phase 1 to occur. This situation cannot be explained by the standard kinetics that involves a fixed amount of luminal Ca²⁺ binding sites. A new mathematical model was developed that assumes an increasing SR Ca²⁺ buffering capacity in response to an increase of the luminal SR [Ca²⁺] that is called Kinetics-on-Demand (KonD) model. This approach can explain both phase 1 and the refractory period associated with a recovered [Ca²⁺]_FSR. Additionally, our data suggest that active SERCA pumps are a requisite for KonD to be functional; otherwise luminal SR Ca²⁺ binding proteins switch to standard kinetics. The importance of KonD Ca²⁺ binding properties is twofold: a more efficient Ca²⁺ release process and that [Ca²⁺]_FSR and Ca²⁺-bound to SR proteins ([Ca²⁺]_BSR) can be regulated separately allowing for Ca²⁺ release to occur (provided by Ca²⁺-bound to luminal Ca²⁺ binding proteins) without an initial reduction of the [Ca²⁺]_FSR.     

Characterisation of mutations in 77 patients with X-linked myotubular myopathy,including a family with a very mild phenotype

X-linked myotubular myopathy is characterised by neonatal hypotonia, muscle weakness and respiratory distress in affected males, leading often to early death, although prolonged survival is observed in milder forms, or as a result of prolongation of ventilation support. It is caused by mutations in the MTM1 gene, which encodes a phosphatase called myotubularin, which has been highly conserved during evolution, down to yeasts ( S. cerevisiae and S. pombe). To date, 251 mutations have been identified in unrelated families, corresponding to 158 different disease-associated mutations, which are widespread throughout the gene. We have found additional mutations in 77 patients, including 35 novel ones. We identified a missense mutation N180K in a 67-year-old grandfather (the oldest known patient with an MTM1 mutation), previously suspected to have autosomal centronuclear myopathy, and in his two grandsons also mildly affected. Mild and moderate phenotypes associated with novel missense mutations and with a translation initiation defect mutation are discussed, as well as severe phenotypes associated with particular novel mutations. With the present report, 192 different mutations in the MTM1 gene have been described in 328 families. The spectrum of mutations is now enlarged from the very severe classic neonatal phenotype to very mild phenotype allowing survival to the age of 67 years.     

Multilocus Bayesian Estimates of Intra-Oceanic Genetic Differentiation,Connectivity, and Admixture in Atlantic Swordfish (Xiphias gladius L.)

Previous genetic studies of Atlantic swordfish (Xiphias gladius L.) revealed significant differentiation among Mediterranean, North Atlantic and South Atlantic populations using both mitochondrial and nuclear DNA data. However, limitations in geographic sampling coverage, and the use of single loci, precluded an accurate placement of boundaries and of estimates of admixture. In this study, we present multilocus analyses of 26 single nucleotide polymorphisms (SNPs) within 10 nuclear genes to estimate population differentiation and admixture based on the characterization of 774 individuals representing North Atlantic, South Atlantic, and Mediterranean swordfish populations. Pairwise F _ST values, AMOVA, PCoA, and Bayesian individual assignments support the differentiation of swordfish inhabiting these three basins, but not the current placement of the boundaries that separate them. Specifically, the range of the South Atlantic population extends beyond 5°N management boundary to 20°N-25°N from 45°W. Likewise the Mediterranean population extends beyond the current management boundary at the Strait of Gibraltar to approximately 10°W. Further, admixture zones, characterized by asymmetric contributions of adjacent populations within samples, are confined to the Northeast Atlantic. While South Atlantic and Mediterranean migrants were identified within these Northeast Atlantic admixture zones no North Atlantic migrants were identified respectively in these two neighboring basins. Owing to both, the characterization of larger number of loci and a more ample spatial sampling coverage, it was possible to provide a finer resolution of the boundaries separating Atlantic swordfish populations than previous studies. Finally, the patterns of population structure and admixture are discussed in the light of the reproductive biology, the known patterns of dispersal, and oceanographic features that may act as barriers to gene flow to Atlantic swordfish.     

Hepatoma-Derived Growth Factor-Related Protein-3 Is a Novel Angiogenic Factor

Hepatoma-derived growth factor-related protein-3 (Hdgfrp3 or HRP-3) was recently reported as a neurotrophic factor and is upregulated in hepatocellular carcinoma to promote cancer cell survival. Here we identified HRP-3 as a new endothelial ligand and characterized its in vitro and in vivo functional roles and molecular signaling. We combined open reading frame phage display with multi-round in vivo binding selection to enrich retinal endothelial ligands, which were systematically identified by next generation DNA sequencing. One of the identified endothelial ligands was HRP-3. HRP-3 expression in the retina and brain was characterized by Western blot and immunohistochemistry. Cell proliferation assay showed that HRP-3 stimulated the growth of human umbilical vein endothelial cells (HUVECs). HRP-3 induced tube formation of HUVECs in culture. Wound healing assay indicated that HRP-3 promoted endothelial cell migration. HRP-3 was further confirmed for its in vitro angiogenic activity by spheroid sprouting assay. HRP-3 extrinsically activated the extracellular-signal-regulated kinase ½ (ERK1/2) pathway in endothelial cells. The angiogenic activity of HRP-3 was independently verified by mouse cornea pocket assay. Furthermore, in vivo Matrigel plug assay corroborated HRP-3 activity to promote new blood vessel formation. These results demonstrated that HRP-3 is a novel angiogenic factor.     

Structure–activity relationships amongst 4-position quinoline methanol antimalarials that inhibit the growth of drug sensitive and resistant strains of Plasmodium falciparum

Utilizing mefloquine as a scaffold, a next generation quinoline methanol (NGQM) library was constructed to identify early lead compounds that possess biological properties consistent with the target product profile for malaria chemoprophylaxis while reducing permeability across the blood–brain barrier. The library of 200 analogs resulted in compounds that inhibit the growth of drug sensitive and resistant strains of Plasmodium falciparum. Herein we report selected chemotypes and the emerging structure–activity relationship for this library of quinoline methanols.     

Insecticidal Constituents from the Argentine Liverwort Plagiochila bursata

The new 2,3‐secoaromadendrane 1 , together with the known compounds plagiochilines A and M ( 2 and 3 , resp.), fusicogigantone A ( 4 ), and 1,4‐dimethylazulene ( 5 ) were isolated from an Argentine collection of the liverwort Plagiochila bursata. Structures were elucidated by extensive 1D‐ and 2D‐NMR studies. Compounds 2 and 4 , incorporated to the larval diet at 100 μg per g of diet, reduced the larval growth of Spodoptera frugiperda (Lepidoptera: Noctuidae) by 66±29% and 25±8% and produced 55 and 75% larval mortality at early instars and 20 and 25% pupal mortality, respectively. Treatment with compound 2 also produced abdomen and wing malformation in adults leading to impossibility to mate.