A tree-based algorithm for determining the effects of solvation on the structure of salivary gland tripeptide NH3+-D-PHE-D-GLU-GLY-COO-

A D-enantiomeric analog of the submandibular gland rat-1 tripeptide FEG (Seq: NH(3)(+)-Phe-Glu-Gly-COO(-)) called feG (Seq: NH(3)(+)-D-Phe-D-Glu-Gly-COO(-)) was examined by molecular dynamics simulations in water. Previous in vacuo simulations suggested a conformation consisting predominantly of interactions between the Phe side chain and glutamyl-carboxyl group and a carboxyl/amino termini interaction. The solvated peptide was simulated using two approaches which were compared-a single 400-ns simulation and a "simulation tree." The "tree" approach utilized 45 10-ns simulations with different conformations used as initial structures for given trajectories. We demonstrate that multiple short duration simulations are able to describe the same conformational space as that described by longer simulations. Furthermore, previously described in vacuo interactions were confirmed with amendments: the previously described head-to-tail arrangement of the amino and carboxyl termini, was not observed; the interaction between the glutamyl carboxyl and Phe side chain describes only one of a continuum of conformations present wherein the aromatic residue remains in close proximity to the glutamyl carbonyl group, and also interacts with either of the two available carboxyl groups. Finally, utilizing only two separate 10-ns trajectories, we were able to better describe the conformational space than a single 60-ns trajectory, realizing a threefold decrease in the computational complexity of the problem.     

Inhibitors of gap junctions attenuate myogenic tone in cerebral arteries

The effects of two structurally distinct inhibitors of gap junction communication were studied by using three different forms of vasoconstriction in pressurized rat middle cerebral arteries. The sensitivity of myogenic tone (at 60 mmHg), vasopressin-induced tone (10 nM, at 20 mmHg), and depolarizing solution-induced tone (80 mM K(+), at 20 mmHg) to inhibition by heptanol (1.0 microM to 3.0 mM) or 18alpha-glycyrrhetinic acid (18alpha-GA, 1.0 to 50 microM) were determined. Pressure-induced myogenic tone was inhibited by heptanol (IC(50) = 0.75 +/- 0.09 mM) and 18alpha-GA ( approximately 30 microM). Vasopressin-induced vasoconstriction was also inhibited by heptanol (IC(50) = 0.4 +/- 0.3 mM) and 18alpha-GA (>1 microM). Depolarizing solution-induced vasoconstriction was less sensitive to inhibition by heptanol compared to vasopressin (P < 0.01) or pressure-induced constriction (P < 0.05). However, 18alpha-GA did not inhibit depolarization-induced constriction. Sharp microelectrode experiments on isolated arteries revealed stable membrane potentials, with no detectable effect of heptanol (1 mM) or 18alpha-GA (20-30 microM) on the average membrane potential at 20 mmHg. However, approximately 20% of impaled cells (5 of 28) exhibited uncharacteristic oscillations in membrane potential after pharmacological uncoupling. At 60 mmHg a approximately 7- to 9-mV hyperpolarization and corresponding vasodilation (approximately 50%) was observed, and the frequency of membrane potential oscillations doubled (9 of 23 cells). These data indicate that gap junctions play an important role in the maintenance and modulation of membrane potential and tone in cerebral resistance arteries.     

Synthesis of 1-(2-naphthylsulfonyl)pyrazole-C-glycosides

2-Naphthylsulfonylhydrazine was reacted with aromatic aldehydes or aldehydo sugars to give the corresponding hydrazones which undergo Michael addition reactions with malononitrile or ethyl cyanoacetate to form pyrazole derivatives.     

An imbalance in antioxidant defense affects cellular function: the pathophysiological consequences of a reduction in antioxidant defense in the glutathione peroxidase-1 (Gpx1) knockout mouse

Aerobic cells are subjected to damaging reactive oxygen species (ROS) as a consequence of oxidative metabolism and/or exposure to environmental toxins. Antioxidants limit this damage, yet peroxidative events occur when oxidant stress increases. This arises due to increased radical formation or decreased antioxidative defenses. The two-step enzymatic antioxidant pathway limits damage to important biomolecules by neutralising superoxides to water. However, an imbalance in this pathway (increased first-step antioxidants relative to second-step antioxidants) has been proposed as etiological in numerous pathologies. This review presents evidence that a shift in favor of hydrogen peroxide and/or lipid peroxides has pathophysiological consequences. The involvement of antioxidant genes in the regulation of redox status, and ultimately cellular homeostasis, is explored in murine transgenic and knockout models. The investigations of Sod1 transgenic cell-lines and mice, as well as Gpx1 knockout mice (both models favor H(2)O(2) accumulation), are presented. Although in most instances accumulation of H(2)O(2) affects cellular function and leads to exacerbated pathology, this is not always the case. This review highlights those instances where, for example, increased Sod1 levels are beneficial, and indicates a role for superoxide radicals in pathogenesis. Studies of Gpx1 knockout mice (an important second-step antioxidant) lead us to conclude that Gpx1 functions as the primary protection against acute oxidative stress, particularly in neuropathological situations such as stroke and cold-induced head trauma, where high levels of ROS occur during reperfusion or in response to injury. In summary, these studies clearly highlight the importance of limiting ROS-induced cellular damage by maintaining a balanced enzymatic antioxidant pathway.     

Coumarins from Malaysian Micromelum minutum

In a continuation of our study of the Rutaceae, detailed chemical investigation on Micromelum minutum (Rutaceae) collected from Sepilok, Sabah, Malaysia gave four new coumarins. The structures of the coumarins have been fully characterised by spectroscopic methods as 3",4"-dihydrocapnolactone 1, 2',3'-epoxyisocapnolactone 2, 8-hydroxyisocapnolactone-2',3'-diol 3 and 8-hydroxy-3",4"-dihydrocapnolactone-2',3'-diol 4.     

Zinc efficiency is correlated with enhanced expression and activity of zinc-requiring enzymes in wheat

Zinc (Zn) is an essential micronutrient for plants. The ability of plants to maintain significant yields under low Zn is termed Zn efficiency (ZE) and its genetic and mechanistic basis is still not well understood. Previously, we showed that root Zn uptake did not play a role in ZE. In the current study, Zn-efficient and -inefficient wheat (Triticum aestivum) genotypes were grown for 13 d in chelate buffer nutrient solutions at low (0.1 pM), sufficient (150 pM), and high (1 microM) Zn(2+) activities and analyzed for root-to-shoot translocation of Zn, subcellular leaf Zn distribution, and activity and expression of the Zn-requiring enzymes in leaves. No correlation between ZE and Zn translocation to the shoot was found. Furthermore, total and water-soluble concentrations of leaf Zn were not associated with ZE, and no differences in subcellular Zn compartmentation were found between Zn-efficient and -inefficient genotypes. However, the expression and activity of the Zn-requiring enzymes copper (Cu)/Zn superoxide dismutase (SOD) and carbonic anhydrase did correlate with differences in ZE. Northern analysis suggested that Cu/ZnSOD gene expression was up-regulated in the Zn-efficient genotype, Kirgiz, but not in inefficient BDME. Under Zn deficiency stress, the very Zn-efficient genotype Kirgiz and moderately Zn-efficient Dagdas exhibited an increased activity of Cu/ZnSOD and carbonic anhydrase when compared with Zn-inefficient BDME. These results suggest that Zn-efficient genotypes may be able to maintain the functioning of Zn-requiring enzymes under low Zn conditions; thus, biochemical Zn utilization may be an important component of ZE in wheat.     

Effects of Nigella sativa L. and Urtica dioica L. on selected mineral status and hematological values in CCl4-treated rats

This study was designed to investigate the effects of Nigella sativa L. (NS), known as black seed, or/and Urtica dioica L. (UD), known as stinging nettle root, treatments on serum Na, K, Cl, and Ca levels and some hematological values of CCl₄-treated rats. Sixty healthy male Sprague-Dawley rats, weighing 250–300 g, were randomly allotted into 1 of 4 experimental groups: A (CCl₄-only treated), B (CCl₄+UD treated), C (CCl₄+NS treated), and D (CCl₄+UD+NS treated), each containing 15 animals. All groups received CCl₄ (0.8 mL/kg of body weight, subcutaneously, twice a week for 90 d starting d 1). In addition, B, C, and D groups also received the daily ip injection of 0.2 mL/kg NS and/or 2 mL/kg UD oils for 45 d starting d 46. Group A, on the other hand, received only 2 mL/kg normal saline solution for 45 d starting d 46. Blood samples for the biochemical analysis were taken by cardiac puncture from five randomly chosen rats in each treatment group at the beginning, d 45, and d 90 of the experiment. The CCl₄ treatment for 45 d significantly (p<0.05) increased the serum K and Ca and decreased (p<0.05) the red blood cell count (RBC), white blood cell count (WBC), packed cell volume (PCV), and Hb levels without changing (p>0.05) the serum Na and Cl levels. NS or UD treatments (alone or combination) for 45 d starting d 46 significantly (p<0.05) decreased the elevated serum K and Ca levels and also increased (p<0.05) the reduced RBC, WBC, PCV, and Hb levels. It is concluded that NS and/or UD treatments might ameliorate the CCl₄-induced disturbances of anemia, some minerals, and body’s defense mechanism in CCl₄-treated rats.     

In vivo and in vitro effects of some plant hormones on rat erythrocyte carbonic anhydrase and glucose-6-phosphate dehydrogenase activities

The present study was undertaken to determine in vivo and in vitro effects of some plant growth regulators on rat erythrocyte carbonic anhydrase (CA) and glucose-6-phosphate dehydrogenase (G6PD) activities. Both in vivo and in vitro, spermidine and kinetin did not affect enzymatic activities of CA and G6PD, whereas putrescine decreased these activities, and abscisic acid increased them. Since plants use such growth regulators, their effects should be considered on mammals consuming them since they may possess important biological effects.     

Melatonin reduces glial reactivity in the hippocampus, cortex, and cerebellum of streptozotocin-induced diabetic rats

Hyperglycemia plays a critical role in the development and progression of diabetic neuropathy. One of the mechanisms by which hyperglycemia causes neural degeneration is via the increased oxidative stress that accompanies diabetes. Metabolic and oxidative insults often cause rapid changes in glial cells. Key indicators of this response are increased synthesis of glial fibrillary acidic protein (GFAP) and S100B, both astrocytic markers. In the present study, we examined glial reactivity in hippocampus, cortex, and cerebellum of streptozotocin (STZ)-induced diabetic rats by determining the expression of GFAP and S-100B and we evaluated the effect of melatonin on the glial response. Western blot measurement of contents in brain regions after 6 weeks of STZ-induced diabetes indicated significant increases in these constituents compared with those in nondiabetic controls. Administration of melatonin prevented the upregulation of GFAP in all brain regions of diabetic rats. Using GFAP immunohistochemistry, we observed an increase in GFAP immunostaining in the hippocampus of STZ-diabetic rats relative to levels in the control brains. Treatment with melatonin resulted in an obvious reduction of GFAP-immunoreactive astrocytes in hippocampus. Like GFAP, S100B levels also were increased in all three brain areas of diabetic rats, an effect also reduced by melatonin treatment. Finally, the levels of lipid peroxidation products were elevated as a consequence of diabetes, with this change also being prevented by melatonin. These results suggest that diabetes causes increased glial reactivity possibly due to elevated oxidative stress, and administration of melatonin represents an achievable adjunct therapy for preventing gliosis.