Purification and functional characterization of type II DNA topoisomerase from rat testis and comparison with topoisomerase II from liver

A number of studies in yeast have shown that DNA topoisomerase TI is essential for chromosome condensation and disjunction during mitosis at the metaphase/anaphase transition and meiosis I. Accordingly, kinetic and mechanistic studies have implied a role for topoisomerase rr in chromosome disjunction. As a step toward understanding the nature and role of topoisomerase II in a mammalian germline in vivo, we have purified topoisomerase II from rat testis to homogeneity and ascertained several of its catalytic activities in conjunction with that of the purified enzyme from liver. The purified enzymes appeared to be monomers under denaturing conditions; however, they differed in their relative molecular mass. Topoisomerase II from testis and liver have apparent molecular masses of 150 +/- 10 kDa and 160 +/- 10 kDa, respectively. The native molecular mass of testis topoisomerase II as assayed by immunoblot analysis of cell-foe extracts, prepared in the presence of SDS and a number of protease inhibitors, corroborated with the size of the purified enzyme. Both enzymes are able to promote decatenation and relax supercoiled DNA substrates in an ATP and Mg2+-dependent manner. However, quantitative comparison of catalytic properties of topoisomerase II from testis with that of the enzyme from liver displayed significant differences in their efficiencies. Optimal pH values for testis enzyme are 6.5 to 8.5 while they are 6 to 7.5 for the liver enzyme. Intriguingly, the relaxation activity of liver topoisomerase II was inhibited by potassium glutamate at 1 M, whereas testis enzyme required about half its concentration. These findings argue that topoisomerase II from rat testis is structurally distinct from that of its somatic form and the functional differences between the two enzymes parallels with the physiological environment that is unique to these two tissues.

Structure of nonactin-calcium perchlorate, C40H64O12.Ca(ClO4)2, and a comparative study of metal-nonactin complexes

M r= 975.9, orthorhombic, Pnna, a = 20.262 (3), b= 15.717 (2), c= 15.038 (1)A, V= 4788.97 A 3, z = 4, D x = 1.35 Mg m -3, Cu Kct radiation, 2 = 1.5418 A, /t = 2.79 mm -1, F(000) -= 2072, T = 293 K, R = 0.08, 3335 observed reflections. The molecular structure and the crystal packing are similar to those observed in the nonactin complexes of sodium thiocyanate and potassium thiocyanate. The eight metal-O distances are nearly the same in the potassium complex whereas the four distances involving carbonyl O atoms are shorter than the remaining four involving the tetrahydrofuran-ring O atoms in the Na and the Ca complexes. This observation can be explained in terms of the small ionic radii of Na + and Ca 2+, and leads to a plausible structural rationale for the stronger affinity of nonactin for K + than for the other two metal ions.

Silicon Tetrachloride/Sodium Iodide as a Convenient and Highly Regioselective Ether Cleaving Reagent

Abstract is not available.

Alternatives to sodium metabisulphite for blackspot prevention in prawns

In Australia, prawns are usually treated with a 1% sodium metabisulphite solution to prevent black spot. Two alternatives, Bacterol and Snow Fresh, were compared to the standard metabisulphite treatment used by industry. Bacterol gave similar protection to sodium metabisulphite, while Snow Fresh showed potential as a substitute. The concentrations most appropriate were determined from residue levels after treatment.

Elastic constants of sodium nitrate

Sodium nitrate is isostructural with calcite and crystallizes in the space group DQd. It is one of these substances whose physical properties have been widely investigated. However, a perusal of literature shows that the agreement between the elastic constants obtained by various investigators is not good.

Breakdown voltage and V-Z characteristics of sodium vapour using coaxial cylindrical electrodes

Experimental results for breakdown voltage of sodium vapour measured for the first time using coaxial cylindrical electrodes of fixed gap distance (5 mm) and pressure (corrected to2 0 "C) in the range2 1 to 652 Pa are reported, and are founfdo l ltoow Paschen's Law. The investigations also reveal that V th-Ie characteristics are pressure dependent; the current during the breakdown and the buoifl dc-uurpre nt after a breakdoiws nei ther positive or negative. in spite of the central cylinder being always maintained at a positive potential

Effect of chelating anions on metal-crown interaction. Part III. X-ray structure of potassium picrate complex of benzo-15-crown-5

The cr~¢stal structure of [potassium(benzo-15-crown-5)](picrate) shows that in the complex the metal is sandwiched between two crowns andhas no interaction with plcrate.

Total body potassium in cystic fibrosis

To further evaluate the nature of malnutrition, define at-risk groups, and confirm the efficacy of nutritional supplementation on body composition in cystic fibrosis (CF), we have conducted longitudinal and cross-sectional studies of total body potassium (TBK) in 161 unselected CF subjects aged 1 month to 17 years. TBK was determined by measurement of40K in a whole body counter, reflecting body cell mass (BCM), the vital work-performing and growing cellular component of the body. Compared with normal TBK data for age and sex from pooled measurements of 1,629 healthy children aged 1 week to 17 years, CF infants (n = 12) diagnosed by newborn screening were depleted in TBK at diagnosis and showed catch-up with therapy by 1 year; CF children aged 2-17 years (n = 140) showed a tendency for inadequate accretion of TBK (and thus BCM) with increasing age, although the normal correlation between TBK and weight and height was maintained in the majority suggesting a pattern of nutritional stunting of growth; and malnourished CF children (n = 9) showed significant catchup in TBK with long-term nutritional rehabilitation (85-98% of TBK predicted for weight and height). These studies suggest that potentially serious, but possibly correctable deficits, in the growth of the body cell mass as measured by TBK occur commonly in CF. These deficits may be established very early in life and if not corrected lead to progressive nutritional growth retardation with increasing age. © 1989 Raven Press, Ltd., New York.

X-ray and ultraviolet photoelectron spectroscopy studies of the interaction of carbon monoxide with oxygen adsorbed on silver covered with potassium, caesium or barium

X-ray and He(II) ultraviolet photoelectron spectroscopy studies of the interaction of CO with oxygen on potassium-, caesium- and barium-covered Ag surfaces have shown the formation of carbonate at 300 K. While on a caesium-covered surface only carbonate formation takes place, on the potassium- and barium-covered surfaces molecularly chemisorbed CO is also formed. The variation of the surface concentrations of carbon and oxygen with temperature has been examined and a reaction sequence for the interaction of CO with adsorbed oxygen on potassium-, caesium- and barium-covered Ag surfaces is suggested.

Dynamics of the ammonium ion in the ferroelectric transition in sodium ammonium selenate, NaNH4SeO4·2H2O-an E.S.R. study

E.S.R. investigations of γ-irradiated ferroelectric Sodium ammonium selenate, NaNH4SeO4•2H2O and its deuteriated analogue in powder and single crystal forms have led to a deeper understanding of the nature of the ferroelectric transition of 180 K. A number of paramagnetic species formed due to γ-irradiation have been identified on the basis of their g-factors and hyperfine features from 77Se. The radical SeO4 has been used as a microprobe in studying the phase transition.

Heparin versus 0.9% sodium chloride intermittent flushing for the prevention of occlusion in long term central venous catheters in infants and children

Background Guidelines and clinical practice for the prevention of complications associated with central venous catheters (CVC) around the world vary greatly. Most institutions recommend the use of heparin to prevent occlusion, however there is debate regarding the need for heparin and evidence to suggest 0.9% sodium chloride (normal saline) may be as effective. The use of heparin is not without risk, may be unnecessary and is also associated with increased cost. Objectives To assess the clinical effects (benefits and harms) of intermittent flushing of heparin versus normal saline to prevent occlusion in long term central venous catheters in infants and children. Search Methods The Cochrane Vascular Trials Search Co-ordinator searched the Specialised Register (last searched April 2015) and the Cochrane Register of Studies (Issue 3, 2015). We also searched the reference lists of retrieved trials. Selection criteria Randomised controlled trials that compared the efficacy of normal saline with heparin to prevent occlusion of long term CVCs in infants and children aged up to 18 years of age were included. We excluded temporary CVCs and peripherally inserted central catheters (PICC). Data Collection and Analysis Two review authors independently assessed trial inclusion criteria, trial quality and extracted data. Rate ratios were calculated for two outcome measures - occlusion of the CVC and central line-associated blood stream infection. Other outcome measures included duration of catheter placement, inability to withdraw blood from the catheter, use of urokinase or recombinant tissue plasminogen, incidence of removal or re-insertion of the catheter, or both, and other CVC-related complications such as dislocation of CVCs, other CVC site infections and thrombosis. Main Results Three trials with a total of 245 participants were included in this review. The three trials directly compared the use of normal saline and heparin, however, between studies, all used different protocols for the standard and experimental arms with different concentrations of heparin and different frequency of flushes reported. In addition, not all studies reported on all outcomes. The quality of the evidence ranged from low to very low because there was no blinding, heterogeneity and inconsistency between studies was high and the confidence intervals were wide. CVC occlusion was assessed in all three trials (243 participants). We were able to pool the results of two trials for the outcomes of CVC occlusion and CVC-associated blood stream infection. The estimated rate ratio for CVC occlusion per 1000 catheter days between the normal saline and heparin group was 0.75 (95% CI 0.10 to 5.51, two studies, 229 participants, very low quality evidence). The estimated rate ratio for CVC-associated blood stream infection was 1.48 (95% CI 0.24 to 9.37, two studies, 231 participants; low quality evidence). The duration of catheter placement was reported to be similar between the two study arms, in one study (203 participants). Authors' Conclusions The review found that there was not enough evidence to determine the effects of intermittent flushing of heparin versus normal saline to prevent occlusion in long term central venous catheters in infants and children. Ultimately, if this evidence were available, the development of evidenced-based clinical practice guidelines and consistency of practice would be facilitated.

Solid-state Thermal Polymerization of Sodium Acrylate

Initiation and propagation processes in thermally initiated solid-state polymerization of sodiumvacrylate have been studied. The kinetics of initiation, followed with the electron spin resonancev technique, leads to an activation energy E of 28.8 kcal/mol, which is attributed to the formation of dimeric radicals. The activation energy of 16 f 1 kcaVmol obtained for the solid-state polymerization of sodium acrylate by chemical analysis and differential scanning calorimetry has been attributed to the propagation process.

Effects of foliar application of potassium nitrate on suppression of Alternaria leaf blight of cotton (Gossypium hirsutum) in northern Australia

Alternaria leaf blight is the most prevalent disease of cotton in northern Australia. A trial was conducted at Katherine Research Station, Northern Territory, Australia, to determine the effects of foliar application of potassium nitrate (KNO3) on the suppression of Alternaria leaf blight of cotton. Disease incidence, severity and leaf shedding were assessed at the bottom (1-7 nodes), middle (8-14 nodes) and the top (15+ nodes) of plants at weekly intervals from 7 July to 22 September 2004. Disease incidence, severity and shedding at the middle canopy level were significantly higher for all treatments than those from bottom and top canopies. Foliar KNO3, applied at 13 kg/ha, significantly (P < 0.05) reduced the mean disease incidence, severity and leaf shedding assessed during the trial period. KNO 3 significantly (P < 0.001) reduced the disease severity and leaf shedding at the middle canopy level. Almost all leaves in the middle canopy became infected in the first week of July in contrast to infection levels of 50-65% at the bottom and top of the canopy. Disease severity and leaf shedding in the middle canopy were significantly (P < 0.05) lower in KNO 3-treated plots than the control plots from the second and third weeks of July to the second and third weeks of August. This study demonstrates that foliar application of KNO3 may be effective in reducing the effect of Alternaria leaf blight of cotton in northern Australia.

Thermoanalysis of ammonium perchlorate and sodium nitrate mixture

A binary mixture of ammonium perchlorate-sodium nitrate in molar proportion undergoes partial fusion at 223°C and the transformation of the mixture to sodium perchlorate-ammonium nitrate occurs in the broad endothermic region. The mixture was heated and quenched at various temperatures in a differential thermal analysis assembly. Thermogravimetric analysis, X-ray diffraction, and infrared spectroscopic techniques were used to determine the composition of the quenched sample in order to explain the overall thermal phenomenon. Visual observations of the morphological changes that occur during the course of heating were made using a hot-stage microscope, 30–350°C.

The efficacy of a vitamin D3 metabolite for improving the myofibrillar tenderness of meat from Bos indicus cattle

The influence of a once only administration of a metabolite of vitamin D3 (HY [middle dot] D(R)-25-hydroxy vitamin D3) on myofibrillar meat tenderness in Australian Brahman cattle was studied. Ninety-six Brahman steers of three phenotypes (Indo-Brazil, US and US/European) and with two previous hormonal growth promotant (HGP) histories (implanted or not implanted with Compudose(R)) were fed a standard feedlot ration for 70 d. Treatment groups of 24 steers were offered daily 10 g/head HY [middle dot] D(R) (125 mg 25-hydroxyvitamin D3) for 6, 4, or 2 d before slaughter. One other group of 24 steers was given the basal diet without HY [middle dot] D(R). Feed lot performance, blood and muscle samples and carcass quality data were collected at slaughter. Calcium, magnesium, potassium, sodium, iron and Vitamin D3 metabolites were measured in plasma and longissimus dorsi muscle. Warner-Bratzler (WB) shear force (peak force, initial yield) and other objective meat quality measurements were made on the longissimus dorsi muscle of each steer after ageing for 1, 7 and 14 d post-mortem at 0-2 [deg]C.There were no significant effects of HY [middle dot] D(R) supplements on average daily gain (ADG, 1.28-1.45 kg/d) over the experimental period. HY [middle dot] D(R) supplements given 6 d prior to slaughter resulted in significantly higher (P (R)) by phenotype/HGP interaction for peak force (P = 0.028), in which Indo-Brazil steers without previous HGP treatment responded positively (increased tenderness) to HY [middle dot] D(R) supplements at 2 d when compared with Indo-Brazil steers previously given HGP. There were no significant effects of treatment on other phenotypes. HY [middle dot] D(R) supplements did not affect muscle or plasma concentrations of calcium, potassium or sodium, but did significantly decrease plasma magnesium and iron concentrations when given 2 d before slaughter. There were no detectable amounts of 25-hydroxyvitamin D3 in the blood or muscle of any cattle at slaughter.