Effects of the Na+/H+-exchange inhibitor Hoe 642 on intracellular pH, calcium and sodium in isolated rat ventricular myocytes

The inhibitors of the Na+/H+-exchange (NHE1) system Hoe 694 and Hoe 642 possess cardioprotective effects in ischaemia/reperfusion. It is assumed that these effects are due to the prevention of intracellular sodium (Nai) and calcium (Cai) overload. The purpose of the present study was to investigate the effects of Hoe 642 on intracellular pH, Na+ and Ca2+ (pHi, Nai and Cai) in isolated rat ventricular myocytes under anoxic conditions or in cells in which oxidative phosphorylation had been inhibited by 1.5 mmol/l cyanide. In cells which were dually loaded with the fluorescent dyes 2, 7-biscarboxyethyl-5,6-carboxyfluorescein (BCECF) and Fura-2, anoxia caused acidification of the cells (from pHi 7.2 to pHi 6.8) and an increase in Cai from about 50 nmol/l to about 1 micromol/l. The decrease in pHi began before the cells underwent hypoxic (rigor) contracture, whereas Cai only began to rise after rigor shortening had taken place. After reoxygenation, pHi returned to its control value and Cai oscillated and then declined to resting levels. It was during this phase that the cells rounded up (hypercontracture). When 10 micromol/l Hoe 642 was present from the beginning of the experiment, pHi and Cai were not significantly different from control experiments. At reoxygenation, pHi did not recover, but Cai oscillated and returned to its resting level. To monitor Nai, the cells were loaded with the dye SBFI. After adding 1.5 mmol/l cyanide or 100 micromol/l ouabain, Nai increased from the initial 8 mmol/l to approximately 16 mmol/l. Hoe 642 or Hoe 694 (10 micromol/l) did not prevent the increase in Nai. In contrast, the blocker of the persistent Na+ current R56865 (10 micromol/l) attenuated the CN--induced rise in Nai. The substance ethylisopropylamiloride was not used because it augmented considerably the intensity of the 380 nm wavelength of the cell's autofluorescence. In conclusion, the specific NHE1 inhibitor Hoe 642 did not attenuate anoxia-induced Cai overload, nor CN--induced Nai and Cai overload. Hoe 642 prevented the recovery of pHi from anoxic acidification. This low pHi maintained after reoxygenation may be cardioprotective. Other possible mechanisms of NHE1 inhibitors, such as prevention of Ca2+ overload in mitochondria, cannot be ruled out. The increase in Nai during anoxia is possibly due to an influx of Na+ via persistent Na+ channels.     

Treatment with the oral growth hormone secretagogue MK-677 increases markers of bone formation and bone resorption in obese young males

The effect of 2 months of treatment with the oral growth hormone (GH) secretagogue MK-677 on markers of bone metabolism was determined in healthy obese male subjects. This was a randomized, double-blind, parallel, placebo-controlled study. Twenty-four healthy obese males, 19-49 years of age, with body mass index > 30 kg/m2 were treated with MK-677 (25 mg/day; n = 12) or placebo (n = 12) for 8 weeks. MK-677 increased markers of bone formation; a 23% increase in the carboxy-terminal propeptide of type I procollagen levels and a 28% increase in procollagen III peptide levels were seen with as little as 2 weeks of MK-677 treatment (p < 0.01 and p = 0.001 vs. placebo, respectively) while a 15% increase in serum levels of osteocalcin was not detected until 8 weeks of treatment (p < 0.01 vs. placebo). Markers of bone resorption were induced within 2 weeks of treatment with MK-677; serum levels of the carboxy-terminal cross-linked telopeptide of type I collagen were increased 26% at 8 weeks (p = 0.001 vs. placebo), and urine hydroxyproline/creatinine and calcium/creatinine ratios at 8 weeks were increased by 23% (p < 0.05 vs. placebo) and 46% (p < 0.05 vs placebo), respectively, MK-677 increased serum insulin-like growth factor binding protein-5 (IGFBP-5) by 43-44% after 2-8 weeks of treatment (p < 0.01 vs. placebo). Serum IGFBP-4 was increased by 25% after 2 weeks of treatment (p < 0.001 vs. placebo) but no significant change from baseline was observed after 8 weeks of treatment. Plasma interleukin-6 was not significantly changed by active treatment. In conclusion, short-term treatment of healthy obese male volunteers with the GH secretagogue MK-677 increases markers of both bone resorption and formation. Large increases in serum levels of IGF-1 and IGFBP-5 and a transient increase in serum IGFBP-4 were found. Future long-term studies are needed to investigate if prolonged treatment with MK-677 increases bone mass.     

Methylmalonic aciduria in pregnancy: a case report

Methylmalonic aciduria is a rare metabolic disorder of amino acid metabolism that is characterized by accumulation of large amounts of methylmalonic acid in the blood and urine. To our knowledge this is the first case report of a patient with methylmalonic aciduria who carried a pregnancy to term; the outcome was favorable despite high levels of methylmalonic acid in the serum and urine.     

Constrained length minimum inductance gradient coil design

A gradient coil design algorithm capable of controlling the position of the homogeneous region of interest (ROI) with respect to the current-carrying wires is required for many advanced imaging and spectroscopy applications. A modified minimum inductance target field method that allows the placement of a set of constraints on the final current density is presented. This constrained current minimum inductance method is derived in the context of previous target field methods. Complete details are shown and all equations required for implementation of the algorithm are given. The method has been implemented on computer and applied to the design of both a 1:1 aspect ratio (length:diameter) central ROI and a 2:1 aspect ratio edge ROI gradient coil. The 1:1 design demonstrates that a general analytic method can be used to easily obtain very short gradient coil designs for use with specialized magnet systems. The edge gradient design demonstrates that designs that allow imaging of the neck region with a head sized gradient coil can be obtained, as well as other applications requiring edge-of-cylinder regions of uniformity.     

E1A second exon requirements for induction of target cell susceptibility to lysis by natural killer cells: implications for the mechanism of action

Recombinant human granulocyte colony-stimulating factor (G-CSF) at a dose of 1 to 300 micrograms/kg/day was administered intravenously to rats daily for 13 weeks. Serum alkaline phosphatase (ALP) activity increased dose-dependently with leukocytosis. Most of the increased leukocytes were segmented neutrophils, and neutrophil alkaline phosphatase (NAP) scores were elevated markedly. Serum ALP activity correlated very well with the segmented neutrophil counts, and the coefficient of correlation was more than 0.97 in both sexes. Pathological examinations revealed splenomegaly and a marked increase in neutrophils in the red pulp of the spleen. In the spleen, phagocytosis of neutrophils by macrophages was observed. These data indicate that the increased ALP was of neutrophil origin. Serum ALP activity may be increased by the direct release of ALP from the high number of neutrophils into the blood, or by the leakage of ALP into the blood mainly from the spleen where many neutrophils are pooled and destroyed by the macrophage system.     

Standing up to the big squeeze

Consumer confidence is at its lowest ebb since 1980. Economic growth is at a standstill & unemployment & inflation are both rising. Here's a front-line report from more than three dozen operators who are fending off the recession's dual pressures of slow sales & rising costs. They are using discount pricing, partnering with vendors, setting pay for performance standards & a variety of other recession-beating practices.     

Effect of a direct magnetic field on the interfacial microstructure between molten aluminium and solid iron

Many processing techniques, such as hot dip aluminizing, bimetal formation, liquid metal corrosion, cementing, welding and diffusion bonding, are basically dependent on interfacial reactions [1-3]. It is therefore important to investigate the formation and growth of intermetallic layers at the interface. There have been several studies carried out to examine chemical compositions and growth kinetics of intermetallic layers in the Al-Fe system [4-9]. Most authors have come to an agreement that…     

Crystal structure of TNF-alpha mutant R31D with greater affinity for receptor R1 compared with R2

Crystal structures have been determined of recombinant human tumor necrosis factor-alpha (TNF-alpha) and its R31D mutant that preferentially binds to TNF receptor R1 with more than seven times the relative affinity of binding to receptor R2. Crystals of the wild-type TNF were of space group P4(1)2(1)2 and had unit cell dimensions of a = b = 94.7 and c = 117.4 A. Refinement of the structure gave an R-factor of 22.3% at 2.5 A resolution. The crystals of TNF R31D mutant diffracted to 2.3 A resolution, and were of identical space group to the wild type with unit cell dimensions of a = b = 95.4 and c = 116.2 A, and the structure was refined to an R-factor of 21.8%. The trimer structures of the wild-type and mutant TNF were similar with a root mean square (r.m.s.) deviation of 0.56 A for Calpha atoms; however, the subunits within each trimer were more variable with an average r.m.s. deviation of 1.00 A on Calpha atoms for pairwise comparison of subunits. Model complexes of TNF with receptors R1 and R2 have been used to predict TNF-receptor interactions. Arg31 in all three subunits of wild-type TNF is predicted to form an ionic interaction with the equivalent glutamic acid in both receptors R1 and R2. Asp31 of the TNF R31D mutant is predicted to interact differently with the two receptors. The side chain of Asp31 in two subunits of the TNF mutant is predicted to form hydrogen bond interactions with Ser59 or Cys70 of R1, while it has no predicted interactions with R2. The loss of three strong ionic interactions of Arg31 and the electrostatic repulsion of Asp31 with Glu in the receptors is consistent with the reduced binding of the R31D mutant to both receptors relative to wild-type TNF. The replacement of these ionic interactions by two weaker hydrogen bond interactions between Asp31 of the R31D mutant and R1, compared with no interactions with R2, is in agreement with the observed preferential binding of the R31D mutant to R1 over R2. Analysis of the structure and function of receptor-discriminating mutants of TNF will help understand the biological role of TNF and facilitate its use as an antitumor agent.      

A MECHANISTICALLY BASED MATHEMATICAL MODEL OF SULFUR DIOXIDE ABSORPTION INTO A CALCIUM HYDROXIDE SLURRY IN A SPRAY DRYER

A mathematical model has been developed to predict So₂ absorption and removal during the constant rate drying period of a spray dryer. The model, based on film theory, treats the atomized slurry droplets as spheres containing discrete sorbent particles of slaked lime with the fluid uniformly distributed around the individual particles. The model includes gas and liquid phase mass transfer coefficients as well as resistance to Ca(OH)₂ dissolution. A sensitivity analysis has been conducted and a comparison was made between pilot-scale experimental data and model-predicted values of S0₂ removal efficiency.     

Field trapping of threeEpinotia species with (Z,Z)-7,9-dodecadienyl acetate (Lepidoptera: Tortricidae)

Field survey of the geometrical isomers of 7,9-dodecadienyl alcohol, acetate, and aldehyde has resulted in attractants and inhibitors for three species of tortricid moths.Epinotia silvertoniensis and an undescribedEpinotia sp. were all attracted to (Z,Z)-7,9-dodecadienyl acetate. AnotherEpinotia sp. was attracted to (Z,Z)-7,9-dodecadienyl acetate and (Z,Z)-7,9-dodecadien-1-ol. Electroantennogram data and inhibition patterns for one of theEpinotia sp. are also reported. In addition,E. criddleana was attracted to lures containing (E)-9-dodecenyl acetate.