Superoxide formation and interaction with nitric oxide modulate systemic arterial pressure and renal function in salt-depleted dogs

To determine the role of superoxide (O(2)(-)) formation in the kidney during alterations in the renin-angiotensin system, we evaluated responses to the intra-arterial infusion of an O(2)(-) - scavenging agent, tempol, in the denervated kidney of anesthetized salt-depleted (SD, n=6) dogs and salt-replete (SR, n=6) dogs. As expected, basal plasma renin activity was higher in SD than in SR dogs (8.4 +/- 1.0 vs. 2.3 +/- 0.6 ng angiotensin 1/ml/hr). Interestingly, the basal level of urinary F(2)-isoprostanes excretion (marker for endogenous O(2)(-) activity) relative to creatinine (Cr) excretion was also significantly higher in SD compared to SR dogs (9.1 +/- 2.8 vs. 1.6 +/- 0.4 ng F(2)-isoprostanes/mg of Cr). There was a significant increase in renal blood flow (4.3 +/- 0.5 to 4.9 +/- 0.6 ml/min/g) and decreases in renal vascular resistance (38.2 +/- 5.8 to 33.2 +/- 4.7 mm Hg/ml/min/g) and mean systemic arterial pressure (148 +/- 6 to 112 +/- 10 mm Hg) in SD dogs but not in SR dogs during infusion of tempol at 1 mg/kg/min for 30 mins. Glomerular filtration rate and urinary sodium excretion (U(Na)V) did not change significantly during tempol infusion in both groups of dogs. Administration of the nitric oxide synthase inhibitor nitro-L-arginine (50 mug/kg/min) during tempol infusion caused a reduction in U(Na)V in SR dogs (47% +/- 12%) but did not cause a decrease in SD dogs. These data show that low salt intake enhances O(2)(-) activity that influences renal and systemic hemodynamics and thus may contribute to the regulation of arterial pressure in the salt-restricted state.     

Effects of Sertraline and Fluoxetine on P-Glycoprotein at Barrier Sites: In Vivo and In Vitro Approaches

Background and Purpose

Retention of substances from systemic circulation in the brain and testes are limited due to high levels of P-glycoprotein (P-gp) in the luminal membranes of brain and testes capillary endothelial cells. From a clinical perspective, P-gp rapidly extrudes lipophilic therapeutic agents, which then fail to reach efficacious levels. Recent studies have demonstrated that acute administration of selective serotonin reuptake inhibitors (SSRI) can affect P-gp function, in vitro and in vivo. However, little is known concerning the time-course of these effects or the effects of different SSRI in vivo.

Experimental Approach

The P-gp substrate, tritiated digoxin ([³H] digoxin), was co-administered with fluoxetine or sertraline to determine if either compound increased drug accumulation within the brains and testes of mice due to inhibition of P-gp activity. We undertook parallel studies in endothelial cells derived from brain microvessels to determine the dose-response and time-course of effects.

Key Results

In vitro, sertraline resulted in rapid and potent inhibition of P-gp function in brain endothelial cells, as determined by cellular calcein accumulation. In vivo, a biphasic effect was demonstrated. Brain accumulation of [³H] digoxin was increased 5 minutes after treatment with sertraline, but by 60 minutes after sertraline treatment, brain accumulation of digoxin was reduced compared to control. By 240 minutes after sertraline treatment brain digoxin accumulation was elevated compared to control. A similar pattern of results was obtained in the testes. There was no significant effect of fluoxetine on P-gp function, in vitro or in vivo.

Conclusions and Implications

Acute sertraline administration can modulate P-gp activity in the blood-brain barrier and blood-testes barrier. This clearly has implications for the ability of therapeutic agents that are P-gp substrates, to enter the brain when co-administered with SSRI.     

Influence of carbon sources on the viability and resuscitation of Acetobacter senegalensis during high-temperature gluconic acid fermentation

Much research has been conducted about different types of fermentation at high temperature, but only a few of them have studied cell viability changes during high-temperature fermentation. In this study, Acetobacter senegalensis, a thermo-tolerant strain, was used for gluconic acid production at 38 °C. The influences of different carbon sources and physicochemical conditions on cell viability and the resuscitation of viable but nonculturable (VBNC) cells formed during fermentation were studied. Based on the obtained results, A. senegalensis could oxidize 95 g l^− 1 glucose to gluconate at 38 °C (pH 5.5, yield 83%). However, despite the availability of carbon and nitrogen sources, the specific rates of glucose consumption (q_s) and gluconate production (q_p) reduced progressively. Interestingly, gradual q_s and q_p reduction coincided with gradual decrease in cellular dehydrogenase activity, cell envelope integrity, and cell culturability as well as with the formation of VBNC cells. Entry of cells into VBNC state during stationary phase partly stemmed from high fermentation temperature and long-term oxidation of glucose, because just about 48% of VBNC cells formed during stationary phase were resuscitated by supplementing the culture medium with an alternative favorite carbon source (low concentration of ethanol) and/or reducing incubation temperature to 30 °C. This indicates that ethanol, as a favorable carbon source, supports the repair of stressed cells. Since formation of VBNC cells is often inevitable during high-temperature fermentation, using an alternative carbon source together with changing physicochemical conditions may enable the resuscitation of VBNC cells and their use for several production cycles.

     

Geometry Effect on Plasmon Frequency in Triangular Nanoprism

Plasmonics - Surface plasmon resonance is one of the important properties of noble metals which can be controlled by shape, size, and composition. This feature helps scientists to detect individual...     

Designing a Novel Recombinant HN Protein with Multi Neutralizing Antigenic Sites and Auto Tag Removal Ability Based on NDV-VIIj for Diagnosis and Vaccination Application

Hemagglutinin–neuraminidase (HN) protein besides its mediation in viral pathogenesis, is composed of various antigenic sites which stimulate production of host’s antibodies. Thus, application of this protein in serological tests and vaccination plays a major role in biosecurity and control programs. In the present study, we designed a recombinant HN protein containing different neutralizing antigenic sites with velogenic patterns, and sub-cloned it into pET-43.1a+ expression vector. The expression of NusA-HN recombinant protein was induced. Affinity chromatography protein purification using HisPur? Ni–NTA was then conducted. Moreover, we performed western-blot technique using HRP-conjugated Anti His-Tag. Results revealed that following induction of recombinant protein, two distinct bands of HN-61 kDa and NusA-63 kDa were purified and identified by western-blotting. We recommend further analysis should be carried out to determine the functional role of this recombinant protein in enzyme-linked immunosorbent assays for Newcastle disease diagnosis. This HN protein containing multi neutralizing antigenic sites might also be applicable in vaccination programs to increase vaccines potency.     

Determinative factors in inhibition of aquaporin by different pharmaceuticals: Atomic scale overview by molecular dynamics simulation

The inhibition of water permeation through aquaporins by ligands of pharmaceutical compounds is considered as a method to control the cell lifetime. The inhibition of aquaporin 1 (AQP1) by bacopaside-I and torsemide, was explored and its atomistic nature was elucidated by molecular docking and molecular dynamics (MD) simulation collectively along with Poisson-Boltzmann surface area (PBSA) method. Docking results revealed that torsemide has a lower level of docking energy in comparison with bacopaside-I at the cytoplasmic side. Furthermore, the effect of steric constraints on water permeation was accentuated. Bacopaside-I inhibits the channel properly due to the strong interaction with the channel and larger spatial volume, whereas torsemide blocks the cytoplasmic side of the channel imperfectly. The most probable active sites of AQP1 for the formation of hydrogen bonds between the inhibitor and the channel were identified by numerical analysis of the bonds. Eventually, free energy assessments indicate that binding of both inhibitors is favorable in complex with AQP1, and van der Waals interaction has an important contribution in stabilizing the complexes.     

Nanoformulation of curcumin protects HUVEC endothelial cells against ionizing radiation and suppresses their adhesion to monocytes: potential in prevention of radiation-induced atherosclerosis

Objectives

To investigated the potential of a novel dendrosomal nanoformulation of curcumin (DNC) in blocking radiation-induced changes in irradiated human umbilical vein endothelial cells (HUVECs), and their adhesion to human THP-1 monocytoid cells.

Results

Co⁶⁰ gamma rays reduced viability, raised the expression of adhesion molecules, ICAM-1, VCAM-1 and E-selectin (mRNA and protein), augmented the adhesion of THP-1 cells to HUVECs, activated NF-κB binding, increased the release of pro-inflammatory cytokines (IL-6, IL-8 and MCP-1) and induced oxidative damage (reduced glutathione declined, while 8-OHdG and TBARS increased). 5 µM DNC significantly inhibited these radiation-induced changes, activated the Nrf-2 pathway, and effectively suppressed THP-1 adhesion to HUVECs, implicating p38 MAPK signaling.

Conclusion

DNC treatment is a potential preventive method against inflammation and vascular damage from ionizing radiation.