The nitric oxide-cGMP signaling pathway plays a significant role in tolerance to the analgesic effect of morphine

Although the phenomenon of opioid tolerance has been widely investigated, neither opioid nor nonopioid mechanisms are completely understood. The aim of the present study was to investigate the role of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway in the development of morphine-induced analgesia tolerance. The study was carried out on male Wistar albino rats (weighing 180-210 g; n = 126). To develop morphine tolerance, animals were given morphine (50 mg/kg; s.c.) once daily for 3 days. After the last dose of morphine was injected on day 4, morphine tolerance was evaluated. The analgesic effects of 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole (YC-1), BAY 41-2272, S-nitroso-N-acetylpenicillamine (SNAP), N(G)-nitro-L-arginine methyl ester (L-NAME), and morphine were considered at 15 or 30 min intervals (0, 15, 30, 60, 90, and 120 min) by tail-flick and hot-plate analgesia tests (n = 6 in each study group). The results showed that YC-1 and BAY 41-2272, a NO-independent activator of soluble guanylate cyclase (sGC), significantly increased the development and expression of morphine tolerance, and L-NAME, a NO synthase (NOS) inhibitor, significantly decreased the development of morphine tolerance. In conclusion, these data demonstrate that the nitric oxide-cGMP signal pathway plays a pivotal role in developing tolerance to the analgesic effect of morphine.     

Chronic Fluoride Exposure Has a Role in Etiology of Coronary Artery Ectasia: Sialic Acid/Glycosaminoglycan Ratio

The sialic acid/glycosaminoglycan ratio was determined in 35 coronary artery ectasia patients and 35 control subjects to determine the possible role of fluoride in the etiology of the disease. The coronary artery ectasia patients and controls were selected from subjects who underwent coronary angiography. The mean serum sialic acid level was significantly lower in patients with coronary artery ectasia (CAE) than in controls (340.3 ± 28.6 vs. 427.0 ± 15.9 μg/mL, respectively; p < 0.001). The mean serum glycosaminoglycan level was significantly higher in patients with CAE than in controls (5,013.1 ± 158.6 vs. 3,833.6 ± 237.1 μg/mL, respectively; p < 0.001). The sialic acid/glycosaminoglycan ratio in patients with coronary artery ectasia was significantly lower than in controls (0.068 ± 0.007 vs. 0.111 ± 0.005; p < 0.001). There was more than 38.7% reduction in this ratio in patients with CAE when compared with controls. We demonstrated that chronic fluoride exposure has an important role in pathogenesis of coronary artery ectasia.     

Regulation of the X Chromosomes in Caenorhabditis elegans

Dosage compensation, which regulates the expression of genes residing on the sex chromosomes, has provided valuable insights into chromatin-based mechanisms of gene regulation. The nematode Caenorhabditis elegans has adopted various strategies to down-regulate and even nearly silence the X chromosomes. This article discusses the different chromatin-based strategies used in somatic tissues and in the germline to modulate gene expression from the C. elegans X chromosomes and compares these strategies to those used by other organisms to cope with similar X-chromosome dosage differences.     

Calcium Binding-Mediated Sustained Release of Minocycline from Hydrophilic Multilayer Coatings Targeting Infection and Inflammation

Infection and inflammation are common complications that seriously affect the functionality and longevity of implanted medical implants. Systemic administration of antibiotics and anti-inflammatory drugs often cannot achieve sufficient local concentration to be effective, and elicits serious side effects. Local delivery of therapeutics from drug-eluting coatings presents a promising solution. However, hydrophobic and thick coatings are commonly used to ensure sufficient drug loading and sustained release, which may limit tissue integration and tissue device communications. A calcium-mediated drug delivery mechanism was developed and characterized in this study. This novel mechanism allows controlled, sustained release of minocycline, an effective antibiotic and anti-inflammatory drug, from nanoscale thin hydrophilic polyelectrolyte multilayers for over 35 days at physiologically relevant concentrations. pH-responsive minocycline release was observed as the chelation between minocycline and Ca²⁺ is less stable at acidic pH, enabling ‘smart’ drug delivery in response to infection and/or inflammation-induced tissue acidosis. The release kinetics of minocycline can be controlled by varying initial loading, Ca²⁺ concentration, and Ca²⁺ incorporation into different layers, enabling facile development of implant coatings with versatile release kinetics. This drug delivery platform can potentially be used for releasing any drug that has high Ca²⁺ binding affinity, enabling its use in a variety of biomedical applications.     

Changes induced by angiotensins and prostaglandin E2 on the release of transmitter from isolated perfused rabbit kidney during periarterial stimulation.

The influence of A II and PGE2 on the rise of perfusion pressure induced by periarterial stimulation and NA were studied in the rabbit isolated perfused kidney. Periarterial stimulation produced an increase in perfusion pressure and the venous outflow superfusing the rabbit aortic strip caused the muscle to contract. Both effects were found to be frequency dependent. NA induced similar effect when given into the renal artery. A II and its N-terminal analogs produced equal potentiation to periarterial stimulation without altering the effect of exogenous NA when added to the perfusion medium. DMGIA II which is a competitive inhibitor of A II inhibited the potentiating affect of A II. PGE2 also inhibited the effect of A II without altering the effect of exogenous NA. Addition of aspirin to the perfusion medium caused a potentiation to periarteral stimulation but did not change the effect of NA. A II added to the perfusion fluid containing aspirin still caused potentiation. From these results it was concluded that: (i) A II-induced potentiation to periarterial stimulation is mediated via specific receptors and probably due to facilitation of the release of transmitter from sympathetic nerve ending. (ii) PGE2 inhibited the release of transmitter. The effect of A II and PGE2 seemed to be mediated by independent mechanisms.     

The effect of iloprost and NDGA in ischemia reperfusion injury in rat liver.

In this study, the effects of iloprost (ZK 36374) and NDGA on warm ischemia and reperfusion injury in rat liver were investigated. Rats were given isotonic saline (control group), iloprost 25 micrograms/kg i.v. (group II) just before warm ischemia or NDGA 10 micrograms/kg i.v. (group III) 5 min before reperfusion or the same drugs were given together (group IV). Serum SGOT, SGPT, and LDH values and tissue malondialdehyde (MDA), glutathione (GSH), prostaglandin (PG)E2, and leukotriene (LT)C4 levels were determined after ischemia-reperfusion injury. Histopathologic examination of the liver was carried out under the light microscope. The serum SGOT, SGPT and LDH levels improved significantly in groups II, III, and IV when compared with the control group (p < 0.05). There was a significant decrease (p < 0.05) in tissue MDA levels and significant increase (p < 0.05) in tissue GSH levels in group I, when compared with group IV and the control groups. The values did not differ significantly in group IV when compared to controls. The LTC4/PGE2 ratio was low and histologic findings were worse in group III. In conclusion, iloprost was found to be beneficial in preventing the ischemia-reperfusion injury in the rat livers. NDGA, either by direct toxic effect or by shifting the arachidonic acid metabolism to the cyclooxygenase route, was not found to be as effective. Iloprost and NDGA did not exert a synergist effect.     

Should We Formulate an Incentivized Model Facilitating Kidney Donation from Living Donors? A Focus on Turkey's Current System

Kidney transplantation is a lifesaving medical treatment. However, very high demand for kidneys with low kidney donation causes a black market that exploits patients’ desperation and donors’ vulnerability. The current kidney donation programs fail to produce promising results to avoid illegal and unethical kidney trafficking and commercialism. Even though the primary goal of kidney donation is to increase the number of deceased organ donations, in some countries, like Turkey, due to religious or cultural concerns, it is impossible to supply adequate deceased kidney donations. In this view, the aim of this paper is to examine kidney trafficking in the scope of Turkey's current organ donation system and propose a new model, named the Incentivized Kidney Donation Model (IKDM), to increase kidney donation from living donors. The model encompasses the following benefits offered to kidney donors; lifetime health insurance, exemptions from copayments/contribution shares, priority when receiving an organ, priority when finding a job, income tax exemptions for salaried employees, and free or discounted public utilities. This normative model has the potential to promote donors’ altruistic acts as well as the solidarity and loyalty among members of a society without violating ethical values and internationally accepted principles.