Cognition enhancing abilities of vitamin D,epalrestat and their combination in diabetic rats with and without scopolamine induced amnesia

Persistent hyperglycaemia and scopolamine were used to inflict amnesia in rats. Chronic hyperglycaemia causes metabolic impairment, neuronal dysfunction and oxidative stress causing cognitive impairment. This study aimed to determine anti amnesic activities of vitamin D, epalrestat and their combination against diabetes and scopolamine induced cognitive dysfunction. A total of eighty-eight Wistar albino rats, eleven groups, and 8 rats/Gr., were used. Type 2 diabetes mellitus was induced in all groups, except Gr.1 which was treated with 2 ml normal saline. Gr. 2 to 11 by feeding high fat diet for 28 days followed by single dose streptozotocin 35 mg/kg i.p. Hyperglycemic rats were screened with blood sugar level > 200 mg/dL. Gr. 2 rats were treated with only streptozotocin and Gr. 3 to 6 were treated with streptozotocin and test drugs donepezil 1 mg/kg, vitamin D, 27 mcg/kg, epalrestat 57 mg/kg, vitamin D + epalrestat, per oral, respectively. Gr. 7 rats were treated with only streptozotocin + scopolamine and all others from Gr. 8 to 11 were treated with streptozotocin + scopolamine and donepezil, vitamin D, epalrestat, vitamin D + epalrestat respectively. The gold standard behavioural tests were conducted by using Morris water maze and passive avoidance paradigms after 30–60 min of inj. scopolamine, 0.5 mg/kg, intra-peritoneal. Hippocampal tissue was taken for histopathological and biochemical evaluation. Rats treated with donepezil, vitamin D, epalrestat and vitamin D + epalrestat showed significant improvement in behavioural, biochemical and histopathological parameters as compared to streptozotocin and (streptozotocin + scopolamine) treated rats. This study underscores cognition enhancing abilities of vitamin D and epalrestat, and their combination in diabetic rats with and without scopolamine.     

Replication of endogenous avian retrovirus in permissive and nonpermissive chicken embryo fibroblasts.

Clones of chicken embryo fibroblasts exogenously infected with the endogenous avian retrovirus were analyzed to examine the replication of this virus in permissive (Gr+) and nonpermissive (Gr-) cells. The results demonstrate that the endogenous virus was capable of infecting both Gr+ and Gr- cells with equal efficiency. Infected clones of Gr+ and Gr- cells differed, however, in two significant ways. At the time of their initial characterization, the Gr+ clones produced 100- to 1,000-fold more virus than the Gr- clones. Further, the amount of virus produced by Gr+ clones did not change significantly during serial passage of the cells. In contrast, continued passage of the infected Gr- clones resulted in a gradual increase in the amount of virus produced. Individual clones of infected Gr- cells produced infectious virus at rates that, initially, differed by a factor of more than 10(4). The large differences in the production of virus by these clones could not be explained by equally large differences in the number of infected cells within the clonal populations. Greater than 80% of the clonal populations examined ultimately produced virus at rates that were not significantly different from the rates observed in infected Gr+ cells. Virus produced by these infected Gr- cells exhibited the same restricted replication upon establishing a new infection in nonpermissive cells. Analysis of the appearance of free and integrated viral DNA sequences during endogenous virus infection of Gr+ and Gr- cells demonstrated that, after an initial delay in the synthesis of free viral DNA in Gr- cells, the nonpermissive cells ultimately acquired as many integrated viral DNA sequences as were found in infected Gr+ cells. These results indicate that a majority of the infectious particles of the endogenous virus are capable of establishing infection in a Gr- cell and, ultimately, of producing virus at a rate that is not significantly different from that produced by infected Gr+ cells. The virus produced from the Gr- cells is not a stable genetic variant of the original endogenous virus that is capable of unrestricted replication in nonpermissive cells. The reduced efficiency with which the endogenous virus initially replicates in nonpermissive cells and the increased length of time required for infected Gr- cells to produce maximal virus titers suggest that the endogenous virus may utilize a different mechanism of replication in Gr+ and Gr- fibroblasts.     

Modification by oral contraceptives in rat of 14C acetate incorporation into platelet lipids.

The in vitro incorporation of acetate 14C in platelets lipids was compared in control female rats (Gr. I) to rats treated for 4 days either by an oral contraceptive ethinyl oestradiol + lynestrenol (Gr. II), or by ethinyl oestradiol alone (Gr. III) or lynestrenol alone (Gr. IV). An increase of 43--45% in the incorporation of acetate could be observed in the two groups (II and III) which received ethinyl oestradiol, while the incorporation in group IV was similar to that of the controls. The lipid fractions of which the synthesis was the most considerably stimulated by the oestrogen treatment, were the neutral lipids as separated from the other lipids by TLC. In groups II and III the incorporation in cholesterol and cholesterol esters was increased by 8 fold and by 10 fold in the free fatty acid fraction. In these two groups, even in the phospholipid fractions PS + PI and PE, the radioactivity was significantly increased. The observed effect of the oral contraceptive studied here on platelet lipid synthesis in female rats, appears to be essentially due to the estrogens, since lynestrenol had only minimal effects in that respect.     

Effect of consumption of fatty acids, calcium, vitamin D and boron with regular physical activity on bone mechanical properties and corresponding metabolic hormones in rats

The consumption of fatty acids, nutrients, and regular physical activity, individually influence bone mechanical properties in rats. To investigate their effects in combination, male rats were divided into the seven groups: G1: regular food and drinking water; G2: same as Gr.1 + physical activity (Whole body vibration; WBV); G3: same as Gr.2 + Calcium, Vit. D, Boron; G4: same as Gr.3 + canola oil; G5: same as Gr.3 + sunflower oil; G6: same as Gr.3 + mix of sunflower oil and canola oil; and G7: same as Gr.3 + coconut oil; and treated for 8 weeks. Analysis between the control with the groups 2 and 3 revealed that vibration in the G2 increased the body weight (P = 0.04), with no other major difference in plasma and bone indices. Comparison between the control with the G4-G7 (the oil groups) revealed that the rats in the G5 had a lower body weight (15 % less) and a significant increase in plasma levels of Estradiol in the G7 was noted. In addition, levels of Testosterone in the G4 and G7, and Free Testosterone in the G7 had a remarkable increase. Similar trend was observed for plasma levels of Vit. D in the G4 and G5. The stiffness and the breaking strength of the femur in the G7, and the breaking strength of the lumbar in the G7 compared to the control and the G4 and G5 was significantly higher and tended to increase in comparison to the G6. Better and stronger measurements observed for coconut oil is warranted to further study its effect on biomechanical properties of bones.     

Regulation of oxidative phosphorylation by liver mitochondria receptors after adaptation by rats to periodic normal pressure and acute hypoxia

It is known that NO-dependent mechanisms are involved in mitochondrial adaptive reactions to different factors. The object of this study was to investigate the role of cholino- and adrenoreceptors in NO-dependent reactions of rat liver mitochondria to acute hypoxia (AH) and intermittent hypoxic training (IHT). Eight groups of Wistar male rats participated in the study. Animals of Gr. I underwent daily i.p. saline injections during 14 days. Gr. II was examined after a single AH test (inhalation of 7% O2, 30 min) with the same saline treatment. Another six groups were exposed to IHT (11% O2, 15-min sessions with 15 min rest intervals, 5 times daily during 14-days), at that 15 min before every IHT session animals underwent i.p. treatment: Gr. III and IV--saline, Gr. V--L-arginine, Gr. VI--NO synthase blocker L-NNA, Gr. VII--L-arginine with alpha-, beta-adrenoblockers phentolamine and obzidane, Gr. VIII--L-arginine with M- and N-cholinoreceptor blockers athropine and benzohexonium. After IHT Gr. IV-VIII were exposed to a single AH test and decapitated just after that. In control rats AH provoked: 1) in the presence of succinate, a 33% augmentation of ADP-stimulated mitochondrial respiration (V3) with a 18% decrease of O2 uptake efficiency (ADP/O ratio); 2) in the presence of alpha-ketoglutarate, a NAD-dependent substrate, no changes in V3 were observed, also 21% augmentation of ADP/O ratio registered. These events were accompanied by 36% increase in succinate dehydrogenase (SDG) activity, two-fold augmentation of malon dialdehyde (MDA) content and 43% increase in diene conjugates (DK). IHT caused reorganization of mitochondrial energy metabolism improving the protection against acute hypoxia. A decrease by 40% in activation of mitochondrial respiration in the presence of succinate (V3--by 40% and V4--by 34%), a reduction of MDA and DK content (by 32% and 20%, respectively), an increase in SGD activity by 31% was observed in Gr. IY compared to Gr. II. Extra exogenous NO (Gr.Y) did not influence V3 and V4 in the presence of succinate, but in the presence of alpha-ketoglutarate decreased them by 9% and 29%, respectively, as well as ADP/O ratio by 28% on the background of SDG inhibition by 24% and the decrease of MDA content by 34%, that is reduced aerobic energy supply and reactive oxygen species production. L-arginine effects were abolished by L-NNA. Effects of cholinoreceptor blockers over L-arginine (Gr. VIII) resembled effects of AH: considerable activation of succinate and alpha-ketoglutarate oxidation in stage V3 by 44% and 75%, respectively, was observed which was accompanied by a decrease in ADP/O by 21% and 31%, and V3/V4 by 15% and 28%, respectively, in comparison to Gr.Y. It indicates that effects of L-arginine are mediated mainly by cholinoreceptors. The effects of adrenoreceptors blockade strengthened the combined effects of IHT with L-arginine treatment, confirming primary role of cholinoreceptors in NO-dependent mitochondrial reactions to IHT. Thus, oxygen uptake and its effective usage depend on dynamic status of adreno- and cholinoreceptors. We conclude that protective effects of the combination of IHT with NO-donor treatment under acute hypoxia are mainly realized through cholinoreceptors.     

Pre-electroconvulsive shock administration of calcium channel blockers reduces retrograde amnesia induced by ECS

Effect of pre-electroconvulsive shock (ECS) administration of calcium channel blockers (CCBs) like verapamil, diltiazem, nifedipine, nimodipine, flunarizine and cinnarizine on retrograde amnesia induced by ECS was examined using passive avoidance paradigm in rats. The groups (Gr 1-7) of adult, male Wistar rats received true ECS with CCBs (5mg/kg; i.p) or vehicle (10 ml/kg; ip) and other groups (Gr 8-14) received sham ECS with CCBs (5mg/kg; i.p) or vehicle (10 ml/kg; i.p). The anti-amnestic activity of CCBs were evaluated using the passive avoidance paradigm in rats. Results showed that, the baseline latencies for all the groups did not differ significantly. Rats receiving true ECS produced significantly lower latencies. There was increase in the post ECS step through latencies of the rats administered CCBs before ECS. Therefore, pre-ECS administration of calcium channel blockers might reduce retrograde amnesia produced by ECS without altering seizure duration.     

Expression of adenosine deaminase and 5'-nucleotidase in artificially induced deciduoma in rat and hamster

Enzymes adenosine deaminase (ADA) and 5-nucleotidase (5-'NT) are known to play active role in tissue/cell proliferation and differentiation. To validate this the two enzymes were studied in artificially induced deciduoma of rat and hamster. The deciduoma was induced by traumatizing one of the uterine horns of progesterone primed animals. Non traumatized horn served as control. The animals were later maintained on progesterone, given alone (Gr.I) or conjointly with estrogen (Gr.II). The weight of each uterine horn was recorded to determine the formation of deciduoma. There was no marked difference between the weights of traumatized and control horn on day 2 post-traumatization (PT), but a progressive rise was noticed after this day in both species. The ADA activity however differed, day and species wise. While in the rats of Gr.I it was low in the traumatized horn on all the days, in the hamsters it was remarkably high from day 2 to 6 PT. In the rats of Gr.II also the activity though was low in the traumatized horn, but on day 2 and 4 only; on day 6 and 7 PT it increased markedly. In hamster, on the contrary, again the enzyme activity was remarkably high on all the three days. The 5'-NT activity, however, did not show any marked difference between the two horns under Gr.I and II in both species. It was rather high in the control horn of each group. The results suggest: (I) the progesterone alone though produces a significant rise in the uterine weight of traumatized horn in both species, the ADA activity increases only in hamster, (2) under the conjoint treatment also the enzyme activity remains high in hamster; and (3) the activity of enzyme 5'-NT does not alter during the deciduoma formation in both the species.     

The effect of gamma-radiation on induction of the hobo element transposition in Drosophila melanogaster

The transposition frequency of the hobo mobile element in four successive generations of Drosophila melanogaster strain y2-717 after an acute gamma-irradiation with a dose of 30 Gr amounted to 7.5 x 10(-4) per site per genome per generation. Under the same conditions, PCR analysis of the genomic DNA of y2-717 flies detected new variants of defective hobo sequence. No changes in the hobo localization and PCR products compared with the control were detected in the case of single irradiation with doses of 3 and 30 Gr. The localizations of hobo element on polytene chromosomes of y2-717 strain did not change during 11 generations after five exposures of flies to 30 Gr. Irradiation of a highly unstable D. melanogaster strain y+743 did not increase the number of families with mutant progeny, yet increased the total number of mutant descendants almost twofold, from 5 to 9%.     

Changes in the mitotic cycle of Chinese hamster cells and the repair of radiation damage in cells following the action of ionizing radiation

Using DNA flow cytofluorimetry technique, the effect of ionizing and gamma irradiation on cell cycle in Chinese hamster cells of clone CHO K1 773 and of its derivative EBR-30 resistant to ethidium bromide was examined. Irradiation in doses of 1 and 5.5 Gr leads to a reduced rate of cell passing from G1 into S phase, to a prolonged S phase and to a larger postsynthetic block in EBR-30 cells than in 773 cells. Our data correlate with some delay in repair of gamma-induced (200 Gr) DNA single-strand breaks in the EBR-30 clone. Clones under investigation are not distinguished in their survival. Our results may arise from deficiency in some regulatory process usually involved in cell response to radiation-induced lesions.     

The regulation of the DNA repair process in mammalian cells. IV. The role of DNA polymerases in the epidermal growth factor regulation of the repair of single-stranded DNA breaks induced by ionizing radiation in Swiss 3T6 mouse cells]

A study was made of the repair of ionizing radiation-induced DNA single-strand breaks (SSB) in proliferating and quiescent mouse Swiss 3T6 cells and in those stimulated from the quiet status by epidermal growth factor in combination with insulin, in the presence of specific inhibitors of DNA polymerase alpha and delta (aphidicolin) and DNA polymerase beta (2', 3'-dideoxythymidine-5'-triphosphate). The repair of DNA SSB induced by X-ray-irradiation (10 Gr) or by gamma-ray irradiation (150 Gr) is more sensitive to aphidicolin independently of cell proliferating status. Aphidicolin inhibits the recovery of single-strand DNA in quiescent and mitogen-stimulated cells three times stronger than in proliferating cells. The influence of 2', 3'-dideoxythymidine-5'-triphosphate on the rate of DNA SSB repair in cells of all the three types does not differ. Thus, the decrease in DNA repair efficiency in quiescent cells is connected with a decrease in the activity of aphidicolin-sensitive DNA polymerase, apparently DNA polymerase alpha. It is suggested that the regulation action of mitogens on the DNA SSB repair may be determined by qualitative changes of this enzyme or of some conditions in which it functions. The involvement of DNA polymerase delta in this process is not excluded.     

DNA polymerase III of Enterococcus faecalis: expression and characterization of recombinant enzymes encoded by the polC and dnaE genes

Enterococcus faecalis (Ef) dnaE and polC, the respective genes encoding the DNA replication-specific DNA polymerase III E and DNA polymerase III C, were cloned and engineered for expression in Escherichia coli as hexahistidine (his6)-tagged recombinant proteins. Each gene expressed a catalytically active DNA polymerase of the expected molecular weight. The recombinant polymerases were purified and each was characterized with respect to catalytic properties, inhibitor sensitivity, and recognition by specific antibody raised against the corresponding DNA polymerase III of the model Gram-positive (Gr(+)) organism, Bacillus subtilis (Bs). In conclusion, the properties of each Enterococcus polymerase enzymes were similar to those of the respective B. subtilis enzymes.     

Quantitation of specific igg,iga, and igm antibodies directed against four species of basidiomycetes

Specific IgG, IgA, and IgM antibodies to aqueous extracts of Coprinus quadrifidus, Pleurotus ostreatus, Calvatia cyathiformis, and Psilocybe cubensis were assessed using an enzyme linked immunosorbent assay (ELISA) in basidiomycete radioallergosorbent test (RAST) positive atopics (Gr 1), RAST negative atopics (Gr 2), and RAST negative, non-atopics (Gr 3). ELISA values are presented as mean optical density ± sem. For C. quadrifidus, elevated specific IgA levels (0.33 ± 0.08, p=0.02) were shown in Gr 1, as compared with Gr 2 (0.129 ± 0.04) and Gr 3 (0.163 ± 0.02). For P. ostreatus, specific IgA levels (0.534 ± 0.15) were also elevated (p=0.003) in Gr 1, when compared with Gr 2 (0.389 ± 0.01) and Gr 3 (0.121 ± 0.03). For C. cyathiformis and P. cubensis, specific IgA levels in Gr 1 were higher than those in Gr 2 and Gr 3, however, these were not significantly elevated. For P. cubensis, specific IgM levels were elevated (p=0.03) in Gr 2 (0.666 ± 0.081) when compared with Gr 1 (0.505 ± 0.056) and Gr 3 (0.413 ± 0.045), respectively. No other differences were observed among the groups in any species tested. These data confirm that isotypes, other than IgE, are produced against Basidiomycetes, also, RAST positive, atopic subjects have a tendency to make higher levels of specific IgA, than RAST negative subjects.     

The influence of estradiol and progesterone on the concentrations of uterine oxytocin receptors and plasma PGFM in response to oxytocin in ovariectomized gilts

Peripubertal gilts (n = 25) were treated with corn oil (CO) or ovarian steroids, one month following an ovariectomy. The first day of treatment was assigned as the first day of the experiment. The gilts received: Group (Gr) I (n = 4)--CO (2 mL x day(-1) from 1st to 12th day), Gr II (n = 4) and Gr III (n = 4)--progesterone (P4; 10 to 100 mg x day(-1) from 1st to 12th day), Gr IV (n = 5)--estradiol benzoate (EB; 400 microg x day(-1) from 1st to 3rd day), Gr V (n = 4) and Gr VI (n = 4)--EB + P4 (EB 400 microg x day(-1) from 1st to 3rd day, 20 microg x day(-1) at 6th and 9th day, 50 microg at 12th day plus P4 10 to 100 mg from 4th to 15th day). All gilts were injected with oxytocin (OT; 20 IU; i.v.) on the following days of the experiment: 13th (Gr I and Gr II), 15th (Gr III and Gr IV), 16th (Gr V) and 18th (Gr VI). Concentrations of the PGF2alpha metabolite--PGFM were determined in blood samples, collected from 30 min before to 120 min after OT injection. Baseline PGFM concentrations (30 min before OT) differed among treatment groups and were the highest in Gr V and Gr VI (P < 0.01 vs. other groups). The magnitude of the PGFM response to OT increased only in four of the five gilts of Gr IV and in three of the four gilts of Gr VI, and it was higher (P = 0.009) in Gr VI than in Gr IV. In the remaining groups, PGFM concentrations did not increase above the baseline in response to OT. The day after OT injection, oxytocin receptors (OTR) were found in the uterine tissues of all animals studied. The lowest OTR concentrations were in Gr I--75.5 +/- 11.2 fmol x mg protein(-1) and the highest in Gr IV--712.9 +/- 86.7 fmol x mg protein(-1); (P < 0.05 vs. other groups). The values of K of OTR differed among groups (P < 0.001) and ranged from 1.62 +/- 0.44 nM in Gr I to 12. 08 +/- 1.9 nM in Gr VI. A positive correlation (r = 0.54; P < 0.01) between plasma E2 and uterine OTR concentrations was observed. In conclusion, E2 and P4 are involved in both PGF2 synthesis/secretion and OTR formation, however, full PGF response to OT does not develop before puberty. Estrogens are evident stimulators of uterine OTR synthesis ingilts.     

Synthesis and characterization of Tyr(Bzl)9,11,13,15 and Tyr9,11,13,15 gramicidin A

Tyr(Bzl) and Tyr gramicidin A were prepared by the solid phase method using a 4-(oxymethyl)-Pam resin and Bpoc as alpha-amino-protecting group. The benzylated analog [Gr.T(Bzl)] was purified by chromatography on silica gel and then on LH60 Sephadex. Removal of benzyl groups was carried out by hydrogenolysis and the debenzylated derivative (Gr.T) was purified in the same way. Both gramicidins were checked and characterized by t.l.c., HPLC, circular dichroism, 1H n.m.r. and single channel measurements. CD spectra were found to be different for Gr.T(Bzl) and Gr.T and strongly dependent upon the solvent and the concentration. Single channel conductance of Gr. T is slightly lower than that of Gr.A (A Gr.T approximately equal to 0.7 A Gr.T).     

Seasonal changes in blood serum protein fractions and in activity of AspAT and AlAT in Arabian brood mares and their foals

In 34 pure breed Arabian horses divided into four groups (Gr. I--10 pregnant mares, Gr. II--7 barren mares, Gr. III--10 foals born in 1981, Gr. IV--7 foals born in 1982) seasonal changes in total blood serum protein, its electrophoretic fractions and the activity of AspAT and AlAT were studied. Seasonal cyclicity was found in all groups in the amount of total serum proteins, and alpha 2- and beta 1-globulin fractions. Cyclicity was found in the level of albumin and activity of AspAT in three groups, not Gr. II, and in gamma-globulin, not Gr. IV. beta 2-globulin and AlAT cyclicity was found in two groups and alpha 1-globulin cyclicity was found only in Gr. II. Out of nine indices studied, cyclicity was found in eight of them in pregnant mares, Gr. I; in seven in older foals, Gr. III; in six in the young foals, Gr. IV; and in five in barren mares, Gr. II.     

Isoproterenol stimulation of the repair of single-stranded DNA breaks in Chinese hamster cells induced by gamma irradiation

The action of the increased intracellular content of adenosine monophosphate (cAMP) in CHO-K1 cells (clones 773 and ADr112eb), treated with isoproterenol, on gamma-induced DNA single-strand breaks repair has been investigated. The hormonal treatment stimulates gamma-induced (180 Gr) DNA single-strand repair during the post-irradiation incubation (45 min) by 75 +/- 16%. The results show the involvement of the cAMP system in radiosensitivity of cultured mammalian cells and in regulation of cellular mechanisms of DNA repair.     

Marrow culture studies in adult acute myeloid leukemia at diagnosis and during complete remission

We used the human placental conditioned medium stimulated single layer agar culture technique to study the in vitro growth of marrow cells from 62 adult patients with acute myeloid leukemia (AML). Bone marrow cells were cultured from 50 patients at the time of initial diagnosis, 19 patients in early remission and 20 patients during their full complete remission. Marrow cultures from untreated patients exhibited heterogeneous growth patterns ranging from complete growth failure to excessive microcluster formation. We classified the growth patterns into 4 groups: (1) Gr I: normal growth, (2) Gr II: no growth, (3) Gr III: decreased growth, (4) Gr IV: excessive growth of microclusters. At presentation, none had Gr I growth; Gr II growth was observed in 23; Gr III in 14 and Gr IV in 13. A predominance of no growth were seen in M1 and M3 subtypes, while Gr IV growth was more commonly observed in M2 or M4 subtype. We were unable to correlate the culture findings with age or white cell count. The present results not only indicated that AML at diagnosis was characterized by abnormal granulopoiesis but also demonstrated that leukemic progenitor cells were heterogeneous with different capacities to express their proliferating potential in vitro. Except few with decreased growth, the growth characteristics generally returned to normal with successful remission induction. Both Gr II and Gr IV growth patterns were not observed either in early remission or during full complete remission.     

Fate of the autologous tri-cusp-valved pericardial conduit in the right ventricular outflow tract of growing pigs.

No perfect valve or valved conduit is currently available to reconstruct the right ventricular outflow tract (RVOT) in pediatric patients. To investigate the fate of autologous pericardial valved conduit, twenty piglets weighing 12.2 +/- 1.4 kg were divided into two groups. In 10 of them, the pericardium was immersed in 0.6% glutaraldehyde for 5 minutes (Gr PG) and then washed with normal saline. In the other 10 pigs, the pericardium was immersed in normal saline only (Gr PN) after procurement. Afterwards the autologous pericardium was tailored as designed to build a tri-cusp-valve inside the pericardial conduit with reconstruction of the sinus of Valsalva. This conduit was connected to the pulmonary trunk (PT) distally and RVOT proximally without a pump. The PT was then doubly ligated just above the annulus. The pigs survived 114 +/- 92 days in Gr PG and 82 +/- 50 days in Gr PN. The body weight increased to 42 +/- 29 kg in Gr PG and 30 +/- 9 kg in Gr PN. No cusps adhered to the conduit wall in either group. In Gr PN, the valve became retracted; in 7 of them an aneurysm developed proximal to the stenotic pulmonary valve, while only one pig in Gr PG developed an aneurysm. In Gr PG, the leaflet and conduit showed evidence of growth. In contrast, no evidence of valve growth was found in Gr PN. Calcification was evident more in Gr PG than in Gr PN either on the leaflet (9/10 vs. 5/10) or in the wall of conduit (8/10 vs. 6/10), but the differences were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Interaction of gramicidin with DPPC/DODAB bilayer fragments

The interaction between the antimicrobial peptide gramicidin (Gr) and dipalmitoylphosphatidylcholine (DPPC)/dioctadecyldimethylammonium bromide (DODAB) 1:1 large unilamellar vesicles (LVs) or bilayer fragments (BFs) was evaluated by means of several techniques. The major methods were: 1) Gr intrinsic fluorescence and circular dichroism (CD) spectroscopy; 2) dynamic light scattering for sizing and zeta-potential analysis; 3) determination of the bilayer phase transition from extrinsic fluorescence of bilayer probes; 4) pictures of the dispersions for evaluation of coloidal stability over a range of time and NaCl concentration. For Gr in LVs, the Gr dimeric channel conformation is suggested from: 1) CD and intrinsic fluorescence spectra similar to those in trifluoroethanol (TFE); 2) KCl or glucose permeation through the LVs/Gr bilayer. For Gr in BFs, the intertwined dimeric, non-channel Gr conformation is evidenced by CD and intrinsic fluorescence spectra similar to those in ethanol. Both LVs and BFs shield Gr tryptophans against quenching by acrylamide but the Stern-Volmer quenching constant was slightly higher for Gr in BFs confirming that the peptide is more exposed to the water phase in BFs than in LVs. The DPPC/DODAB/Gr supramolecular assemblies may predict the behavior of other antimicrobial peptides in assemblies with lipids.