EPR investigations of the influence of N,N′-methylene-bisacrylamide (NNMBA) crosslinks on the coordination structure of Cu(II) complexes of poly (N-2-aminoethylacrylamide)s

Summary The coordination structures of Cu(II) complexes of amino functions supported on polyacrylamides with varying extents of NNMBA-crosslinks were followed by EPR techniques. The geometry of the Cu(II) complexes changes with increasing crosslinking. The covalency of the Cu-N bond also depends on the extent of the NNMBA-crosslinking in the polymer-support.     

Effect of Crospovidone on the Physical Properties of Acetaminophen Tablets

Acetaminophen tablets containing minimum amount of excipients and varying amounts of cross linked polyvinyl pyrrolidone were prepared under accurately controlled conditions of compression speed and pressure. The disintegration time, dissolution rate, crushing force, friability as well as effect of temperature and humidity on these parameters during storage were determined. Increasing proportions of the cross linked polymer (1-10%) did not influence crushing force or friability but significantly decreased disintegration and dissolution time. Satishctory tablets with desired properties were obtained by incorporation of optimum quantity of crospovidone. Storage of acetaminophen tablets at room temperature and humidity for a period of 4 weeks did not alter any of the physical properties tested weekly. However the combined effect of elevated temperature and humidity on tablet properties, especially on the dissolution time was significant. The influence of incorporation of equal amounts of crospovidone intragranularly and intra-plus extragranularly on the properties of granules and tablets were also evaluated with scaled-up formulations.     

Vitamin E deficiency in dogs does not alter preferential incorporation of RRR-alpha-tocopherol compared with all rac-alpha-tocopherol into plasma

The plasma and lipoprotein transport of RRR and all rac-alpha-tocopherols, labeled with different amounts of deuterium [2R,4'R,8'R-alpha-[5-C2H3]tocopheryl acetate (d3RRR-alpha-tocopheryl acetate] and 2RS, 4'RS, 8'RS-alpha-[5,7-(C2H3)2]tocopheryl acetate (d6all rac-alpha-tocopheryl acetate), was studied in adult beagle dogs that had been fed a vitamin E-deficient (-E; two dogs) or supplemented (+E; two dogs) diet for two years. We set out to test the hypothesis that the activity of the hepatic tocopherol binding protein (which is thought to preferentially incorporate RRR-alpha-tocopherol into the plasma) is up-regulated by vitamin E deficiency. Labeled alpha-tocopherols increased and decreased similarly in plasma of both -E and +E dogs. Irrespective of diet, d3RRR-alpha-tocopherol was preferentially secreted in plasma. Thus, vitamin E deficiency in dogs does not markedly increase the apparent function of the hepatic tocopherol binding protein. We also studied vitamin E transport in a German Shepherd dog with degenerative myelopathy (DM). Based on the coincident appearance of d3RRR-alpha-tocopherol in plasma and chylomicrons, we suggest that the abnormality in DM may be associated with abnormal vitamin E transport resulting from an impaired function of the hepatic tocopherol binding protein.     

Mitochondrial DNA polymorphism in Jindo dogs

Mitochondrial DNA (mtDNA) polymorphism was studied in 21 Jindo dogs inhabiting Jin Island off the Korean peninsula. The polymorphism was analyzed with 10 restriction endonucleases that recognize six base pairs. The sizes of the mtDNA fragments produced by digestion using each endonucleases were separated by agarose gel electrophoresis, and the polymorphisms were detected with Japanese mongrel dog mtDNA as a probe. The mtDNA polymorphism in Jindo dogs was observed with four restriction endonucleases, Apa I, EcoR V, Hinc II, and Sty I. However, no polymorphism was detected with BamH I, Bgl II, EcoR I, Hind III, Pst I, or Xba I. The observed restriction endonuclease morphs were classified into 4 types of distinct cleavage patterns. The average number of nucleotide substitutions per nucleotide site in Jindodogs was estimated to be 0.0086. By UPG phylogenetic analysis, the 4 mtDNA types showed only one cluster. This suggests that Jindo dogs have not diverged from the other cluster up to the present and the species is considerably pure.     

Preparation,characterization and alkali metal ion permeation through nylon 666-g-maleic acid membranes

Nylon 666-g-maleic acid membranes were prepared by ⁶⁰Co γ-ray irradiation. The membranes were characterized by measuring their thickness, tensile strength, electrical resistance, membrane potential and permselectivity. Permeability coefficients of KCI, NaCl, Na₂SO₄, NaOH, urea and creatinine were evaluated from dialysis experiments. The charged membranes facilitated the active transport of alkali metal ions under a pH gradient.     

Influence of plasma glucose concentration on rat brain extracellular calcium transients during spreading depression

The objective of this study was to establish whether tissues that are energy compromised, but not energy depleted, demonstrate exaggerated calcium transients when subjected to membrane depolarizations of the spreading depression (SD) type. Anesthetized and artificially ventilated rats were given insulin in order to induce progressively lower plasma glucose concentrations. Spreading depression was elicited by local application of KCl; extracellular calcium concentration (Ca2+e) as well as direct current (DC) potential were recorded. When plasma glucose concentration fell below approximately 3 mM, the duration of the Ca2+e transient gradually increased to values exceeding 500% of control. The increase was associated with a corresponding increase in the duration of the DC potential shift, but the amplitude of the Ca2+e transient did not change. It is concluded that a restriction of glucose (or oxygen) supply, as occurs in hypoglycemia (or hypoxia), prolongs the calcium transient associated with depolarization of the SD type, even though tissue phosphocreatinine and ATP concentrations are normal. The results support the contention that repeated depolarizations, occurring in the penumbral zone of a focal ischemic lesion, could lead to calcium-related damage.