Effect of a polymeric ligand on the formation of some cobalt(III) and copper(II) complexes with partially quarternized poly(4-vinylpyridine)

It was found that the formation constants (K) of CuX(QPVP)^n? (X = ethylenediaminetetraacetate ion (edta) and N-(2-hydroxyethyl)ethylenediamine-N,N′,N′,-triacetate ion (hedta), QPVP = partially quarternized poly(4-vinylpyridine)) increase sharply with increasing degree of quarternization (Q) of QPVP. In the Cu(edta)^2?/QPVP system. K values are 481.mol^?1 for Q = 0%, 8701.mol^?1, for Q = 25%, and 1,1.10³l.mol^?1 for Q = 61%, in aqueous methanol (volume ratio 1:1) at μ = 0,1 mol.l^?1, pH = 8,0. and T = 25°C. In the system CH₃Co(dmg)₂H₂O/QPVP, K decreases linearly with increasing degree of quarternization of QPVP from K = 1,7.10³l.mol^?1 for Q = 0% to K = 95l.mol^?1 for Q = 61% in aqueous methanol (volume ratio 3:7) at μ = 0,05, pH = 8,0, and T = 25°C. The decrease in K is +scribed to a relatively large decrease in the rate constant of the forward reaction and a small increase in that of the backward reaction.     

Fickian diffusion of erucamide (13‐cis‐docosenamide) in poly(laurolactam) (Nylon 12) (PA‐12)

Diffusion of erucamide (13‐cis‐docosenamide) [H₃C— (—CH₂—)₁₁—HC=CH—(—CH₂—)₇—CO— NH₂] (eru) in poly(laurolactam) (Nylon 12) (PA‐12) has been studied in a temperature range from 343 to 353 K. In previous investigations on the diffusion of eru in isotactic poly(propylene) (i‐PP) it was found that the diffusion took place by a non‐Fickian mechanism. This feature was explained by taking into account the microstructure of i‐PP films and the incompatibility of eru and i‐PP. The same experimental method to determine the concentration profiles was previously employed in this system. The experimental profiles have been compared with theoretical curves based on solutions of Fick's diffusion equation for the best fitting, with the appropriate boundary conditions. The measured concentration profiles show a good agreement with the Fickian law. Values of the diffusion coefficient D in the range from 10^–10 to 10^–11 cm²·s^–1 have been obtained. The activation energy for diffusion (E_d) has been calculated from the D values in the temperature range investigated assuming an Arrhenius‐type behaviour. The activation energy has been calculated as E_d = 156 kJ·mol^–1. The values of diffusion coefficients and activation energy are in the range found for some other additives. By using Fujita's equation a good correlation between diffusion coefficient and free volume fraction estimated by means of the Williams‐Landel‐Ferry equation have been found.     

Unvernetzte epoxid-amin-additionspolymere, 6. DSC-untersuchungen zur kinetik der stufenadditionspolymerisation von 2,2-bis[4-(2,3-epoxypropoxy) phenyl] propan mit N,N′-dibenzylethylendiamin und benzylamin

The kinetics of the linear step-growth addition polymerization of equimolar amounts of the diglycidyl ether of bisphenol-A 2,2-bis[4-(2,3-epoxypropoxy)phenyl]propane ( 1 ) with N,N′-dibenzylethylenediamine ( 2 ) and with benzylamine ( 4 ), respectively, is studied by means of differential scanning calorimetry (DSC). For conversions α ≤ 0,90 the experimental results of the isothermic measurements are in excellent agreement with values calculated from the rate equation dα/dt = (k₁ + k₂ α^m) (1 ? α)ⁿ with m + n = 2,5 (m ≈? 1,0, n ≈? 1,5). The first term of this rate equation takes into account both the catalytic and autocatalytic character of the addition polymerization while the exponent n ≈? 1,5 in the second term shows that the effective concentration of one of the addition components is given by the square root of its concentration.     

Syndiotactic styrene‐butadiene block copolymers synthesized with CpTiX3/MAO (Cp = C5H5, X = Cl,F; Cp = C5Me5, X = Me) and TiXn/MAO (n = 3, X = acac; n = 4, X = O‐tert‐Bu)

Copolymers sPS‐B consisting of blocks of syndiotactic polystyrene (sPS) and polybutadiene (B) have been prepared using CpTiX₃ (Cp = C₅H₅, X = Cl, F; Cp = C₅Me₅, X = Me) and TiX_n (n = 3, X = acetylacetonate (acac); n = 4, X = O‐tert‐Bu) activated with methylaluminoxane (MAO). If proper conditions are used, copolymers containing a range of styrene and butadiene molar fractions can be prepared. Structural analysis of these copolymers by means of ¹³C NMR spectroscopy allowed the assignment of different monomer diads (SS, SB, BB; S = styrene, B = butadiene) and the calculation of reactivity ratio products r₁·r₂. Differential scanning calorimetry (DSC) analysis further confirmed the block‐like structure of these copolymers. The melting points (T_m) of syndiotactic styrene sequences decrease as the styrene molar fraction decreases, whereas the glass transition temperature (Tg) increases with decreasing butadiene molar fraction in the copolymer. The polydispersity values (M_w/M_n) determined by GPC suggest that these copolymers are produced by a single site catalyst.     

Screening of clenbuterol,salbutamol and terbutaline in animal feeds

A screening method was developed providing reliable detection of three chemically different β‐agonist model compounds, clenbuterol (50 ppb), salbutamol (500 ppb) and terbutaline (500 ppb). The method comprised an extraction with a mixture of acidic KH₂PO₄ buffer plus methanol followed by detection by enzyme immunoassay using an antibody raised against clenbuterol‐diazo‐bovine serum albumin. The background signals of 107 feed samples of different composition were measured, and 86% were ≤ 2.45 ng clenbuterol equivalents g^‐1. The highest values were 9–56 and 8–98 ng clenbuterol equivalents g^‐1, found in two samples of mineral supplements. Analysis of spiked samples showed mean recoveries of 106 (clenbuterol) to 110% (salbutamol) and coefficients of variation of 13–22% over the different materials. Selected groups of feed materials, such as soybean meal (n = 8), milk replacer (n = 15), dairy concentrate (n = 12), feed for poultry (n = 5), protein concentrate (n = 3) and ground grain meals (n = 5) provided blanks all ≤ 2.58 ng clenbuterol equivalents g^?1 and recoveries between 97 and 124%; the coefficients of variation ranged from 4 to 14%. Although mineral supplements gave slightly less reliable results using this method with varying recoveries (22–189%) a clear differentiation of positives and negatives was always possible at the levels of interest. It may be possible to detect other β‐agonists that show cross‐reactivity with the antibody used for the immunoassay.     

Dependence of the kerr constants of benzene,p-dioxane and poly(oxydiethylene terephthalate) on temperature

The Kerr constants of benzene, p-dioxane, and of poly(oxydiethylene terephthalate) (PDET) in p-dioxane solution were measured at several temperatures. As in the case of some other pure liquids reported in the literature, the values obtained for benzene and p-dioxane are fitted by equations of the type _mK = a + b · T^?1 with a = (0,3 ± 0,6) · 10^?26 m⁵ · V^?2 · mol^?1 and b = (16,0 ± 1,8) · 10^?24 m⁵ · V^?2 · mol^?1 · K for benzene and a = (3,9 ± 0,9) · 10^?26, b = ?(8,2 ± 2,6) · 10^?24, in the same units, for p-dioxane. The values of the mean molar Kerr constant per repeating unit 〈_mK〉/x extrapolated to infinite dilution in the case of PDET yield a values of d(〈_mK〉/x)/dT = (13,5 ± 0,9) · 10^?27 m⁵ · V^?2 · mol^?1 · K^?1, in excellent agreement with the calculated result of 13,2 · 10^?27 (in the same units) reported in the literature.     

1H nuclear magnetic resonance (NMR) as a tool to measure dehydration in mice

Dehydration is a prevalent pathology, where loss of bodily water can result in variable symptoms. Symptoms can range from simple thirst to dire scenarios involving loss of consciousness. Clinical methods exist that assess dehydration from qualitative weight changes to more quantitative osmolality measurements. These methods are imprecise, invasive, and/or easily confounded, despite being practiced clinically. We investigate a non‐invasive, non‐imaging ¹H NMR method of assessing dehydration that attempts to address issues with existing clinical methods. Dehydration was achieved by exposing mice (n = 16) to a thermally elevated environment (37 °C) for up to 7.5 h (0.11–13% weight loss). Whole body NMR measurements were made using a Bruker LF50 BCA‐Analyzer before and after dehydration. Physical lean tissue, adipose, and free water compartment approximations had NMR values extracted from relaxation data through a multi‐exponential fitting method. Changes in before/after NMR values were compared with clinically practiced metrics of weight loss (percent dehydration) as well as blood and urine osmolality. A linear correlation between tissue relaxometry and both animal percent dehydration and urine osmolality was observed in lean tissue, but not adipose or free fluids. Calculated R² values for percent dehydration were 0.8619 (lean, P < 0.0001), 0.5609 (adipose, P = 0.0008), and 0.0644 (free fluids, P = 0.3445). R² values for urine osmolality were 0.7760 (lean, P < 0.0001), 0.5005 (adipose, P = 0.0022), and 0.0568 (free fluids, P = 0.3739). These results suggest that non‐imaging ¹H NMR methods are capable of non‐invasively assessing dehydration in live animals. Copyright © 2015 John Wiley & Sons, Ltd.     

Poly(amido‐amines)s with novel molecular architecture: Synthesis and thermodynamic studies of protonation and metal [Cu(II), Zn(II)] ion complexes

New short chain poly(amido‐amine)s (SPAAs) carrying amido‐ and tertiary amino groups along the polymer chain separated by a single methylene group have been synthesized by polycondensation of N,N′‐bis(2‐chloro‐ or bromo‐acetyl)‐piperazine with N,N ′‐dimethyl‐ethylenediamine, N,N′‐dimethyl‐hexamethylenediamine or 2‐methyl‐piperazine. The basicity of the SPAAs was lower compared to the PAAs obtained previously by polyaddition of bis‐amines to bis‐acrylamides. The shortening of the methylene chain from two (PAAs) to one (SPAAs) reduced the log K values of both tertiary amino groups present in the repeating unit due to inductive effects. Furthermore, the shortening resulted in basicity constants, that depend on pH, with respect to the first step of protonation. The real changes in enthalpy (–ΔH⁰) of protonation of the SPAAs are greater than those found for PAAs, due to the fact that protonated nitrogens and amido C=O groups are closer, favouring the formation of five‐member rings. Five‐membered rings are formed also with metal(II) ions, such as Cu(II) and Zn(II), giving complex species more stable than those of PAAs, with higher log β and larger –ΔH⁰ values. Low entropy changes (ΔS⁰) and molar absorption coefficient (ε) values support strongly a well ordered chelate structure involving three condensed five‐membered rings in an octahedral distorted geometry.     

Differentiation of Acinetobacter calcoaceticus sensu stricto from related Acinetobacter species by electrophoretic polymorphism of malate dehydrogenase, glutamage dehydrogenase and catalase

Acinetobacter baumannii, unnamed Acinetobacter species 3 (studied by P.J.M. Bouvet and P.A.D. Grimont) and unnamed DNA group 13 (studied by I. Tjernberg and J. Ursing) are the most prevalent Acinetobacter species in hospitals. Using the identification scheme of Bouvet and Grimont, it is sometimes difficult to differentiate these species from A. calcoaceticus sensu stricto, a species of the natural environment that has seldom been found associated with human infection. Genetically identified Acinetobacter isolates belonging to A. calcoaceticus sensu stricto (n=12), A. baumannii (n=22), Acinetobacter species 3 (n=15) and DNA group 13 of Tjernberg and Ursing (n=26), Acinetobacter species 10 (n=2), Acinetobacter species 11 (n=2) and 3 strains ungrouped by DNA-DNA hybridization were investigated for electrophoretic separations of L-malate dehydrogenase (MDH), glutamate dehydrogenase (GDH) and catalase (CAT). All A. calcoaceticus sensu stricto isolates were easily differentiated from those of other species investigated by their high MDH values (relative mobility (Rf)=78), their low GDH values (Rf range: 24–28) and CAT values (Rf range: 34–42). Acinetobacter species 3 was differentiated from A. baumannii and DNA group 13 of Tjernberg and Ursing by high CAT values. A. baumannii could not be differentiated from Tjernberg and Ursing DNA group 13. Acinetobacter species 10 was clearly differentiated from Acinetobacter species 11. Once an Acinetobacter is phenotypically identified with the four closely related species investigated here, electrophoretic analysis of MDH, GDH and CAT might be a useful complement to the identification scheme of Bouvet and Grimont for accurately identifying A. calcoaceticus sensu stricto.     

Comparison of a radioallergosorbent (RAST) inhibition method and a monoclonal enzyme linked immunosorbent assay (ELISA) for aeroallergen measurement

Background Mouse and rat urinary proteins are potent occupational allergens for exposed personnel. Methods of measuring airborne allergens differ greatly, and reported levels of allergens vary considerably between laboratories. Objectives To compare the values obtained using two different methods of allergen detection. Methods Air samples were collected in rat rooms in Sweden and the United Kingdom at 2 L/min on to polytetrafluoroethylene (PTFE) filters and extracted in buffer containing 0.5% v/v Tween 20. Airborne rat urinary allergen (RUA) was measured in all samples by both RAST inhibition using a polyclonal human serum pool (UK) and a two monoclonal antibody sandwich ELISA employing antibodies specific for Rat n 1.02 (α_2u-globulin) (Sweden). Results The two methods gave values which were correlated (r² log values = 0.72, P < 0.0001), but differed by several orders of magnitude (median [range] ratio of RAST inhibition/ELISA = 316 [7-26₈₀]. There was a systematic bias; as the absolute values increased, the difference in the measurements increased. The rat urine standards used were antigenically similar. Conclusions A large contrast in RUA values obtained from the two assays was observed in this study. This may be primarily due to methodological differences, but variations in antibody specificities or composition of allergenic epitopes in the air samples may contribute. The results demonstrate that standardization of methods and antibodies is necessary before interlaboratory comparisons can be made.     

Preparation of poly[N-(3-acryloylaminopropyl)carbazole] and its charge transfer complex with 2,4,7-trinitrofluorenone

A new carbazole polymer, poly{1-[3-(9-carbazolyl)propylaminocarbonyl]ethylene} {poly[N-(3-acryloylaminopropyl)carbazole]} ( 6 ) was prepared by radical polymerization of N-(3-acryloylaminopropyl)carbazole ( 5 ). Copolymerization of 5 (M₁) with styrene (M₂) provided the monomer reactivity ratios r₁ = 0,13±0,08 and r₂ = 3,47±0,12. The Q-e values of 5 were calculated as Q₁ = 0,18 and e₁ = +0,10. Fluorescence spectra of 6 and N-(3-isobutyrylaminopropyl)carbazole ( 2 ), prepared as a monomer model compound, were nearly identical, indicating the absence of intramolecular excimer formation for 6 . The stability constants (K) of the charge transfer complexes of 6 and 2 with 2,4,7-trinitrofluorenone (TNF) were determined in 1,2-dichloroethane at 20°C under the conditions of both [ 6 ] or [ 2 ]?[TNF] and [ 6 ] or [ 2 ]?[TNF]. The values of K were 4,9 and 5,2dm³ mol^?1 for 2 when [ 2 ]?[TNF] and [ 2 ]?[TNF], respectively, and 16dm³ mol^?1 for 6 when [ 6 ]?[TNF]. The polymer 6 precipitated, however, when [ 6 ]?[TNF]. As a reference, charge transfer complex formation of poly[1-(9-carbazolyl)-ethylene] [poly(N-vinylcarbazole)] [ 1 ] with TNF was studied under the same conditions. The values of K for 1 were identical when [ 1 ]?[TNF] and [TNF]. These results were explained by assuming a sandwich-type charge transfer complex for 6 , but not for 1 . The space between the carbazolyl groups in 1 would be too small to accomodate a TNF molecule between the chromophores.     

Preparation and polymerization of 2-chloroethyl 2-(methacryloyloxy)ethyl hydrogen phosphate and 2-bromoethyl 2-(methacryloyloxy)ethyl hydrogen phosphate

2-Chloroethyl 2-(methacryloyloxy)ethyl hydrogen phosphate ( 5a ) and 2-bromoethyl 2-(methacryloyloxy)ethyl hydrogen phosphate ( 5b ) were synthesized, characterized, and polymerized with 2,2′-azoisobutyronitrile (AIBN). In the polymerization of 5a in DMF with AIBN, the rate of polymerization was found to be proportional to [AlBN]^0,54 and to [ 5a ]^1,54. The over-all activation energy for the polymerization of 5a was estimated as 59,5 kJ · mol^-1. From the radical copolymerization of 5a with styrene in DMF at 60°C, Q and e values for 5a were evaluated as Q = 2,65 and e = 0,53.     

A chain folding model for poly(decamethylene oxide)

The present paper deals with a small angle X-ray diffraction study of poly(oxydecamethylene) [poly(decamethylene oxide)] ( 1 ) regarding the influence of the chemical nature of the macromolecule on the fold length value. Four fractions of 1 with different molecular weights, were crystallized and the highly diluted solutions of the crystals were deposited in layers just a few microns (μm) thick. These layers were investigated by means of X-ray diffractometry. In all fractions the X-ray long spacing, L, exhibits characteristic values which differs in the ratio of monomeric lengths. The crystal thickness predominantly corresponds to n=2 and 3 times half the value of the unit cell (13,75 Å), for crystallization temperatures T_c≤20°C. At higher temperatures these values increase to n=6. However, at T_c≈?50°C n changes to n=7 or 8 and recovers the value n=6 at higher crystallization temperatures if the substance is still able to crystallize at these temperatures. The multiples of 13,75 Å obtained can be explained by a specific lateral packing of stems according to a proposed model which preserves the unit cell, excludes the oxygen atoms from the folds, and favours the idea of a regularly folded surface layer (4–5 atoms per fold, 2–3 Å thick) and of an ordered three dimensional suprastructure of oxygen atoms within the lattice. Similarly, the increase of the fold length on annealing occurs in steps equal to a whole number of repeating units along the molecular chain.     

Polymer retention mechanism in GPC on active gels, 1. Polystyrene in pure and mixed eluents

The elution behaviour of polystyrene (PS) on spherosil X0A 200 gel in twenty one eluents and its dependence on solvent goodness, as defined by the α exponent of the Mark-Houwink equation, and solvent strength, ?⁰, have been studied. The interstitial volume, V_o, seems to depend solely on solvent goodness, being minimum for good solvents and maximum for solvent mixtures at Θ composition or close to it. By application of a network-limited partition and adsorption mechanism, average pore radii of the gel, r , have been obtained. For ?⁰ > 0,45 a linear dependence with negative slope between r and ?⁰ exists, whereas for ?⁰ < 0,45 r values seem to display a joint dependence on ?⁰ and α·?⁰ α = 0,17 is the limit for obtaining experimental PS elution curves, below that value the polymer being not recovered. A coefficient f, which allows the evaluation of relative distribution coefficients (K_p) is introduced and its numerical values determined for all the eluent systems. The f dependence on ?⁰ and αis similar to that followed by r . At high ?⁰ values partion effects will be mainly responsible for K_p values. However, at low ?⁰ values, besides partition, adsorption effects contribute to the increase of K_p values.     

Comparative in vitro activity of the new quinolone sparfloxacin (CI-978, AT-4140) against nosocomial gram-negative bloodstream isolates

The in vitro activity of sparfloxacin (CI-978, AT-4140), a new quinolone which is active against gram-negative and gram-positive bacteria, and nine other broad-spectrum antibiotics was tested against 128 gram-negative nosocomial bloodstream isolates from separate patients. Sparfloxacin and ciprofloxacin were among the most potent antibiotics againstEscherichia coli (n=40),Enterobacter cloacae (n=18),Klebsiella oxytoca (n=13), andKlebsiella pneumoniae (n=19), with MIC90 values of 0.25 µg/ml. Ciprofloxacin was slightly more potent than sparfloxacin againstSerratia marcescens (n=14), the MIC90 values being 0.25 and 1.0 µg/ml respectively, although all strains were susceptible to both agents. Sparfloxacin was slightly less potent than ciprofloxacin againstPseudomonas aeruginosa (n=24), the MIC90 values being 4.0 and 0.5 µg/ml respectively. Overall, the in vitro activity of sparfloxacin compared favorably with that of ciprofloxacin and the other broad spectrum agents tested against nosocomial gram-negative bloodstream isolates.     

Comparative analysis of the N-genome in diploid and polyploid <Emphasis Type="Italic">Aegilops</Emphasis> species

The genetic classification for the N-genome chromosomes has been developed on the basis of C-banding analysis on the set of Triticum aestivum × Aegilops uniaristata single chromosome addition lines and examination of A. uniaristata ( \text2n = 2 × = 14 {\text{2n = 2}} \times { = 14} , NN), Aegilops ventricosa ( \text2n = 4 × = 28 {\text{2n = 4}} \times { = 28} , DDNN) and Aegilops recta ( \text2n = 6 × = 42 {\text{2n = 6}} \times { = 42} , UUXⁿXⁿNN) accessions carrying intergenomic translocations using fluorescence in situ hybridisation with probes for three repetitive DNA sequences as well as the 5S and 45S rDNA families. The N-genome chromosomes of the tetraploid A. ventricosa show significant changes relative to the diploid progenitor species, while those of the hexaploid A. recta are similar to A. uniaristata with regard to the distribution of C-bands, 45S and 5S rDNA loci and hybridisation sites of all the three families of tandem repeats. The possible mechanisms of N-genome evolution are discussed.     

Pediatric Brainstem Gangliogliomas Show BRAFV600E Mutation in a High Percentage of Cases

Brainstem gangliogliomas (GGs), often cannot be resected, have a much poorer prognosis than those located in more common supratentorial sites and may benefit from novel therapeutic approaches. Therapeutically targetable BRAF c.1799T>A (p.V600E) (BRAF^V600E) mutations are harbored in roughly 50% of collective GGs taken from all anatomical sites. Large numbers of pediatric brainstem GGs, however, have not been specifically assessed and anatomic—and age‐restricted assessment of genetic and biological factors are becoming increasingly important. Pediatric brainstem GGs (n = 13), non‐brainstem GGs (n = 11) and brainstem pilocytic astrocytomas (PAs) (n = 8) were screened by standard Sanger DNA sequencing of BRAF exon 15. Five of 13 (38%) pediatric GG harbored a definitive BRAF^V600E mutation, with two others exhibiting an equivocal result by this method. BRAF^V600E was also seen in five of 11 (45%) non‐brainstem GGs and one of eight (13%) brainstem PAs. VE1 immunostaining for BRAF^V600E showed concordance with sequencing in nine of nine brainstem GGs including the two cases equivocal by Sanger. The equivocal brainstem GGs were subsequently shown to harbor BRAF^V600E using a novel, more sensitive, RNA‐sequencing approach, yielding a final BRAF^V600E mutation frequency of 54% (seven of 13) in brainstem GGs. BRAF^V600E‐targeted therapeutics should be a consideration for the high percentage of pediatric brainstem GGs refractory to conventional therapies.     

Interaction of gonadal steroids and the glucocorticoid corticosterone in the regulation of the L-type Ca(2+) current in rat left ventricular cardiomyocytes

Aim: Gonadal steroids as well as glucocorticoids have been shown to regulate the cardiac L‐type Ca²⁺ current (I_CaL). Herein, we compare the effects of the gonadal steroids testosterone and 17β‐estradiol with the glucocorticoid corticosterone on I_CaL, and investigate the interaction between the gonadal steroids and corticosterone. Methods: Myocytes were isolated from the left ventricular free wall of female and male Wistar rats and investigated using the ruptured‐patch whole‐cell patch‐clamp technique. Results: In myocytes isolated from female rats, 24 h incubation with 100 nm testosterone led to a 33% increase in I_CaL compared with control (?8.8 ± 0.5 pA pF^?1, n = 25 vs. ?6.6 ± 0.4 pA pF^?1, n = 26, P < 0.01, V_Pip = 0 mV). Incubation with 1 μm corticosterone resulted in a 79% increase in I_CaL (?11.8 ± 0.7 pA pF^?1, n = 29, P < 0.001). However, the combination of testosterone and corticosterone did not have any additional effect compared with corticosterone alone (?11.7 ± 0.6 pA pF^?1, n = 25, ns). In cardiomyocytes from male rats, I_CaL was not affected by testosterone, whereas the effect of corticosterone was preserved (P < 0.05). 24 h incubation with 17β‐estradiol increased I_CaL by 32% from ?7.6 ± 0.5 pA pF^?1 (n = 15) to 10.0 ± 0.9 pA pF^?1 (n = 15, P < 0.05). 17β‐estradiol did not exert an additional effect upon co‐incubation with corticosterone and did not have an effect on I_CaL in cardiomyocytes from female rats. Higher concentrations of the gonadal steroids did not result in increased effects. Conclusion: When compared with corticosterone, the in vitro effects of the gonadal steroids are small. However, under conditions in which I_CaL is not fully activated by glucocorticoids, gonadal steroids may significantly contribute to I_CaL regulation.     

Dopamine receptor blockade and synthesis inhibition during exaggerated natriuresis in spontaneously hypertensive rats

Hansell , P. & Sjöquist , M. 1992. Dopamine receptor blockade and synthesis inhibition during exaggerated natriuresis in spontaneously hypertensive rats. Acta Physiol Scand 144 , 269–276. Received 21 September 1990, accepted 11 October 1991. ISSN 0001–6772. Department of Physiology and Medical Biophysics, Biomedical Centre, University of Uppsala, Sweden. The influence of dopamine receptor blockade and synthesis inhibition on natriuresis induced by isotonic saline volume expansion was investigated in anaesthetized spontaneously hypertensive rats and normotensive Wistar-Kyoto rats. The aim of the study was to elucidate the mechanisms underlying the phenomenon of exaggerated natriuresis during volume expansion that has been observed in spontaneously hypertensive rats. Volume expansion, at 5 % of body weight, resulted in a larger and faster natriuretic response in spontaneously hypertensive rats than in Wistar-Kyoto rats. Sixty minutes after commencement of volume expansion the natriuretic response (accumulated sodium excretion) in Wistar-Kyoto rats (n = 8) was only 24% of that in spontaneously hypertensive rats (n = 17). When spontaneously hypertensive rats were pretreated with the dopamine receptor blockers haloperidol (n= 14, 1 mg kg^-1), SCH23390 (n = 8, 30 μg h^-1 kg^-1) or the dopamine synthesis inhibitor benserazide (n = 8, 50 mg kg^-1; n = 5, 100 mg kg^-1), the natriuretic response to volume expansion was only 16, 35, 59 and 42%, respectively, of that in untreated SHR. The corresponding proportion in the haloperidol-treated (n= 8) compared with untreated Wistar-Kyoto rats was 22%. In conclusion, isotonic volume loading results in more pronounced natriuresis in spontaneously hypertensive than in Wistar-Kyoto rats. Dopamine receptor blockade and synthesis inhibition attenuate the expansion of exaggerated natriuresis in spontaneously hypertensive rats and reduces the volume expansion natriuresis in Wistar-Kyoto rats, indicating that the dopamine system plays an important role.     

Unit cell dimensions of poly(ethylene terephthalate)

The density of crystals of poly(ethylene terephthalate), (PETP), Q_c is checked by X-ray diffraction assuming a triclinic unit cell and the indices of reflections as found by Bunn. The following unit cell dimensions are found: a = 4,48Å, b = 5,85Å, c = 10,75 Å, α = 99,5°, β = 118,4°, and γ = 111,2°. This gives the density Q_c as 1,515g/cm³ which is about 4% higher than that reported by Bunn. Negligible differences in spacings for samples annealed at different temperatures (120°C–260°C) have been found. Only for an annealing temperature of 100°C the higher d-values lead to Q_c = 1,484g/cm³. For undrawn PETP films annealed at 250°C the same value of Q_c as for drawn PETP was obtained on the basis of Guinier X-ray patterns. No systematic variation of crystal plane spacings was found for drawn PETP fibers annealed at 220°C and containing mole fractions of 1,7 to 4,2% diethylene glycol, (2,2′-oxydiethanol), as comonomer.