The permeability of hydrophobic membranes to 22Na salts and 14CO2 in low dielectric media

The one-way fluxes of 14CO2 and a series of 22Na (Cl, Br, HCO3, ClO4, I) salts across n-hexadecane-impregnated solid-support liquid membranes have been measured in water and low dielectric media (50-90 vol% dioxane/water). One-way fluxes for 14CO2 (J14CO2) were 0.84 and 1.03 x 10(-9) mol cm-2 s-1 in 75% dioxane (aq.) and water, respectively, across both impregnated cellulose and teflon membranes. 22Na fluxes across impregnated cellulose membranes in 75% dioxane (aq.) ranged from 1.8 to 11.4 x 10(-10) mol cm-2 s-1 and had the order NaCl less than NaBr less than NaHCO3 less than NaClO4 less than Nal. 22Na fluxes across impregnated teflon membranes were slightly smaller, 1.5-7.1 x 10(-10) mol cm-2 s-1, but had the same order for the anions tested. No measurable 22Na fluxes were observed in aqueous media. For NaI and NaClO4 there was a 3-6-fold enhancement of fluxes in 90% dioxane (aq.) compared to 75% dioxane (aq.). The corresponding enhancement for fluxes of NaHCO3, NaBr and NaCl was 1.5-fold. The results are discussed in terms of ion-paired salt transport in low dielectric media.     

Spectroscopic and kinetics studies of the inhibition of pig kidney diamine oxidase by anions

The role of copper in pig kidney diamine oxidase has been probed by examining the effects of potential Cu(II) ligands on the spectroscopic and catalytic properties of the enzyme. In the presence of azide and thiocyanate, new absorption bands are evident at 410 nm (epsilon = 6300 M-1 cm-1) and 365 nm (epsilon = 3000 M-1 cm-1), respectively. These bands are assigned as ligand-to-metal charge-transfer transitions, N3-/SCN- leads to Cu(II). One anion/Cu(II) is coordinated in an equitorial position. Anion binding can be completely reversed by dialysis. The equilibrium constants for diamine oxidase-anion complex formation are 134 M-1 (N3-) and 55 M-1 (SCN-). Azide and thiocyanate are linear uncompetitive inhibitors with respect to the amine substrate when O2 is present at saturating concentrations. Taken together, the data are consistent with a functional role for Cu(II) in diamine oxidase catalysis.     

Temperature dependence of the low frequency dynamics of myoglobin. Measurement of the vibrational frequency distribution by inelastic neutron scattering.

Inelastic neutron scattering spectra of myoglobin hydrated to 0.33 g water (D2O)/g protein have been measured in the low frequency range (1-150 cm-1) at various temperatures between 100 and 350 K. The spectra at low temperatures show a well-resolved maximum in the incoherent dynamic structure factor Sinc(q, omega) at approximately 25 cm-1 and no elastic broadening. This maximum becomes gradually less distinct above 180 K due to the increasing amplitude of quasielastic scattering which extends out to 30 cm-1. The vibrational frequency distribution derived independently at 100 and 180 K are very similar, suggesting harmonic behavior at these temperatures. This result has been used to separate the vibrational motion from the quasielastic motion at temperatures above 180 K. The form of the density of states of myoglobin is discussed in relation to that of other amorphous systems, to theoretical calculations of low frequency modes in proteins, and to previous observations by electron-spin relaxation of fractal-like spectral properties of proteins. The onset of quasielastic scattering above 180 K is indicative of a dynamic transition of the system and correlates with an anomalous increase in the atomic mean-squared displacements observed by M?ssbauer spectroscopy (Parak, F., E. W. Knapp, and D. Kucheida. 1982. J. Mol. Biol. 161: 177-194.) and inelastic neutron scattering (Doster, W., S. Cusack, and W. Petry, 1989. Nature [Lond.]. 337: 754-756.) Similar behavior is observed for a hydrated powder of lysozyme suggesting that the low frequency dynamics of globular proteins have common features.     

Non-species-specific effects of unacylated homoserine lactone and hexylresorcinol, low molecular weight autoregulators, on the growth and development of bacteria

We conducted a comparative study of the effects of alpha-amino-gamma-butyrolactone, the common structural element of extracellular microbial regulators of the homoserine lactone (HSL) group, and of 4-n-hexylresorcinol, an autoregulator of the alkylhydroxybenzene (AHB) group, on the growth and development of gram-positive and gram-negative bacteria. We revealed non-species-specific effects of HSL and AHB and characterized their concentration dependencies. The addition of 10(-5)-10(-3) M HSL or 10(-5)-10(-4) M AHB during the exponential growth phase of the cultures grown on balanced media resulted in cell division arrest and accelerated the transition to the stationary phase that culminated in endospore formation in Bacillus cereus, Alicyclobacillus tolerans, and Sulfobacillus thermosulfidooxidans. When bacilli grew under the cultivation conditions that resulted in a low-zero spore percentage, 10(-4)-10(-3) M HSL cancelled the inhibition of spore formation. In the gram-negative bacteria Pseudomonas aurantiaca and Azotobacter vinelandii, AHB at concentrations of 10(-4) to (1.5-2.5) 10(-4) M induced the formation of dormant cells. Studies with the actinobacterium Streptomyces avermitilis revealed that the HSL effect varied depending on the age of the test cultures. The addition of 10(-4) M HSL during the lag phase of a submerged streptomycete culture accelerated its transition to the stationary phase and induced the formation of endospores, the dormant cells that are regarded as alternatives to exospores (conidia). If HSL (3.64 and 4.55 mg per 1cm2 disc) was locally added to a surface S. avermitilis culture, the growing mycelium formed rings that differed in their density, in the extent of the development of aerial mycelium, and in the presence/absence of exospores. Ring-shaped growth of streptomycete mycelia was also induced by 0.075-0.75 mg of AHB; however, unlike HSL, AHB repressed exospore formation. The data on non-species-specific effects of HSL and AHB suggest that they may perform regulatory functions on the microbial community level.     

Kinetics of bicarbonate transport in human red blood cell membranes at body temperature

We studied unidirectional [14C]HCO3- efflux from human resealed red cell ghosts with 1 mM acetazolamide under self-exchange conditions at pH = pH(i = o) 7.4-9.0 and 0-38 degrees C by means of the Millipore- Swinnex and continuous flow tube filtering techniques. 14CO2 loss from cells to efflux medium and further to the atmosphere was insignificant. [14C]HCO3- efflux was determined at pH 7.8, 38 degrees C under symmetric variation of the HCO3- concentrations (C(i = o)), and asymmetric conditions: C(i) varied, C(o) constant, or C(o) varied, C(i) constant. MM-fit, Jeff = Jmaxeff x C x (C + K1/2)-1, used to describe the concentration dependence of Jeff,o when only C(o) varied, yields at C(i) = 50 mM: K1/2o = 3.8 mMJ, Jmaxeff.o = 20 nmol cm-2 s-1; at C(i) = 165 mM: K1/2o = 10 mM, Jmaxeff.o = 32 nmol cm-2 s-1. When C(i) varied, noncompetitive self inhibition by HCO3- binding (inhibitor constant K1) to an intracellular site was included (MS-fit). Under conditions of (a) symmetry: C(i = o) = 9-600 mM, K1/2s = 173 mM, K1 = 172 mM, and Jmaxeff,s = 120 nmol cm-2 s-1, (b) asymmetry: C(o) = 50 mM, K1/2i = 116 mM, K1 = 136 mM, and Jmaxeff,i = 92 nmol cm-2 s-1. All flux parameters accord with the ping-pong model for anion exchange. The data for C(i) < 200 mM also fit well to the MM equation, but K1/2 and Jmaxeff are different from the MS-fit and are inconsistent with the ping-pong model. Thus, self-inhibition (MS-fit) must be included even at low concentrations. As at 0 degree C, the system is asymmetric: 8-10 times more unloaded transport sites face inward than outward when C(i = o). Jeff,s was not mono-exponentially dependent on temperature at 0-38 degrees C, indicating that the transmembrane anion transport is controlled by several rate constants with different temperature dependencies. Jeff,s was not significantly affected by increasing pH(i = o) from 7.4 to 7.8, but it decreased by 50% when pH was raised to 9.0.     

The Z-conformation of poly(dA-dT).poly(dA-dT) in solution as studied by ultraviolet resonance Raman spectroscopy

Poly(dA-dT).poly(dA-dT) structures in aqueous solutions with high NaCl concentrations and in the presence of Ni2+ ions have been studied with resonance Raman spectroscopy (RRS). In low water activity the effects of added 95 mM NiCl2 in solution stabilize the syn geometry of the purines and reorganize the water distribution via local interactions of Ni-water charged complexes with the adenine N7 position. It is shown that RRS provides good marker bands for a left-handed helix: i) a purine ring breathing mode around 630 cm-1 coupled to the deoxyribose vibration in the syn geometry, ii) a 1300-1340 cm-1 region characterizing local chemical interactions of the Ni2+ ions with the adenine N7 position, iii) lines at about 1483- and 1582 cm-1 correlated to the anti/syn reorientation of the adenine residues on B-Z structure transition, iv) marker bands of the thymidine carbonyl group couplings at 1680- and 1733 cm-1 due to the disposition of the thymidine residues in the Z helix specific geometry. Hence poly(dA-dT).poly(dA-dT) can adopt a Z form in solution. The Z form observed in alternate purine-pyrimidine sequences does not require G-C base pairs.     

Aqueous and salt solutions of quinine of low concentrations: Self-organization,physicochemical properties and actions on the electrical characteristics of neurons

Self-organization, the physicochemical properties of aqueous and salt solutions of quinine and the effects of salt quinine solutions in a wide range of concentrations (1 · 10^?22?1 · 10^?3 M) on the electrical characteristics of the edible snail’s identified neurons were studied. Similar non-monotonic concentration dependencies of physicochemical properties of aqueous and salt quinine solutions at low concentrations are obtained. This allows of predicting the occurrence of biological effects at low concentrations of quinine solutions. Intrinsic (within 5% of the interval) changes in membrane potential, the amplitude and duration of the neuron action potential under the influence of quinine salt solutions at concentrations of quinine of 1 · 10^?20, 1 · 10^?18, 1 · 10^?10 M are found. For these concentrations the extreme values of specific conductivity and pH are shown.     

Laser impact on marine planktonic diatoms: an experimental study using a flow cytometry system

A flow cytometry system was used to evaluate the impact of pulsed laser irradiations from an Nd:YAG laser on two marine coastal water diatoms, Chaetoceros gracilis and Skeletonema costatum. Three flow speeds, i.e. 9, 18 and 27 ml min-1 and three laser fluences, i.e. 0.025, 0.05 and 0.1 J cm-2 pulse-1 were tested during this study. The reduction in cell density and chlorophyll a (chl a) concentrations were monitored by reference to non-irradiated samples as controls. Upon irradiation, the cell density and the chl a concentrations became reduced significantly compared to the control (one way ANOVA p < 0.001 for the cell density in both the species and p < 0.05 for chl a concentrations in both species). A maximum mortality of 0.77 log10 (about 83%) for C. gracilis and 0.68 log10 (about 78%) for S. costatum was observed at 9 ml min-1 flow speed and 0.1 J cm-2 laser fluence. The maximum reduction observed in the chl a concentration was about 26% (control 0.413 and sample 0.306 mg ml-1) for C. gracilis and 27% (control 0.222 and sample 0.16 mg ml-1) for S. costatum, when the flow rate was 9 ml min-1 and the fluence 0.1 J cm-2. In general, mortality increased with an increase in the laser fluence. The results thus show if the cooling water is laser-irradiated to mitigate biofouling, this could result in significant damage to the planktonic flora of the flowing seawater system, which in turn might reduce algal biofilm formation on industrially important structures. The reduction in the chl a concentration showed that the laser irradiations also could result in a significant reduction in the primary productivity of the cooling water.     

Unidirectional K+ fluxes in rat thymocytes stimulated by concanavalin A.

Unidirectional K+ fluxes were estimated in isolated rat thymocytes by 42K exchange kinetics. The cells were either preloaded with isotope and the release of it measured during incubation for one hour at 38 degrees C, or the cellular uptake of isotope during a similar incubation was measured. The influx rate of untreated thymocytes was: 2.3-10(-12) moles cm-2-s-1 and efflux rate: 1.8-10(-12) moles cm-2-s-1. When con A was added to the cells, influx was raised 74% and efflux 65%. Maximal effect was obtained when the concentration of con A was 15 mug/ml, but concentrations as low as 0.75 mug/ml were effective. Hydrocortisone resistant thymocytes responded at least was well as untreated cells to con A, which also raised RNA synthesis rate in the former cells 2.5 times. Using an extracellular marker, 51CrEDTA, intracellular concentrations of some ions was estimated in the thymocytes after one hour incubation: Na+: 30 mmoles/kg water, K+: 177 mmoles/kg water and Cl-:43 mmoles/kg water. Cellular water content: 69%. These values were not found significantly altered when con A was present. Since con A raised influx and efflux to the same extent and no net flux of K+ could be detected, it is proposed that both active and passive transport of K+ was increased by con A. The increased fluxes induced by con A, can apparently not be reversed by removal of con A from the incubation medium or by addition of the inhibiting hapten, alpha-methyl-D-mannoside.     

Novel method for studying plasmid transfer in undisturbed river epilithon

A method for in situ mating experiments is described which involved overnight incorporation of donors containing the mercury resistance plasmid pQM1 and recipients into the epilithon on separate river stones. The stones were then joined to begin the mating. Transfer frequencies obtained were between 2.2 x 10(-1) and 2.5 x 10(-6) per recipient and appeared to depend on the donor-to-recipient ratio (489/1 to 0.0047/1) and not on the river temperature (12 to 19 degrees C). Controls showed that the low density of donors and recipients at the end of the experiment (3.4 x 10(2) to 7.0 x 10(5) cm-2) did not significantly affect the heterotrophic bacterial count (1.43 x 10(6) to 6.39 x 10(6) cm-2) nor the fluorescent-pseudomonad count (2.3 x 10(4) to 9.33 x 10(4) cm-2).     

Novel method for studying plasmid transfer in undisturbed river epilithon.

A method for in situ mating experiments is described which involved overnight incorporation of donors containing the mercury resistance plasmid pQM1 and recipients into the epilithon on separate river stones. The stones were then joined to begin the mating. Transfer frequencies obtained were between 2.2 x 10(-1) and 2.5 x 10(-6) per recipient and appeared to depend on the donor-to-recipient ratio (489/1 to 0.0047/1) and not on the river temperature (12 to 19 degrees C). Controls showed that the low density of donors and recipients at the end of the experiment (3.4 x 10(2) to 7.0 x 10(5) cm-2) did not significantly affect the heterotrophic bacterial count (1.43 x 10(6) to 6.39 x 10(6) cm-2) nor the fluorescent-pseudomonad count (2.3 x 10(4) to 9.33 x 10(4) cm-2).     

Kinetics of adhesion of the oral bacterium Streptococcus sanguis CH3 to polymers with different surface free energies

The kinetics of adhesion of Streptococcus sanguis CH3 from suspension to polymers with different surface free energies were studied by using three bacterial concentrations (2.5 X 10(7), 2.5 X 10(8), and 2.5 X 10(9) cells per ml-1). Substratum surface free energies (gamma s) ranged from 18 to 120 erg cm-2. The kinetics of bacterial adhesion to these surfaces showed a typical two-step adhesion process, indicating an equilibrium in both steps. In the initial adhesion step (step 1), low equilibrium numbers of adhering bacteria were counted on substrata with surface free energies lower than 55 erg cm-2. A maximal number adhered on substrata with higher surface free energies. At the lowest bacterial concentration tested, the highest number of bacteria were found on substrata with a surface free energy around 55 erg cm-2. For each substratum, step 2 started after a characteristic time interval tau, being short (30 min) for gamma s less than 50 and long (120 min) for gamma s greater than 50 erg cm-2. The relationship between the substratum surface free energy and the number of bacteria adhering at equilibrium after step 2 was similar to, although less distinct than, that during step 1 with a slight indication of a bioadhesive minimum around gamma s = 35 erg cm-2. The results are indicative of a two-step adhesion model, in which step 1 is controlled by macroscopic substratum properties.     

Kinetics of adhesion of the oral bacterium Streptococcus sanguis CH3 to polymers with different surface free energies.

The kinetics of adhesion of Streptococcus sanguis CH3 from suspension to polymers with different surface free energies were studied by using three bacterial concentrations (2.5 X 10(7), 2.5 X 10(8), and 2.5 X 10(9) cells per ml-1). Substratum surface free energies (gamma s) ranged from 18 to 120 erg cm-2. The kinetics of bacterial adhesion to these surfaces showed a typical two-step adhesion process, indicating an equilibrium in both steps. In the initial adhesion step (step 1), low equilibrium numbers of adhering bacteria were counted on substrata with surface free energies lower than 55 erg cm-2. A maximal number adhered on substrata with higher surface free energies. At the lowest bacterial concentration tested, the highest number of bacteria were found on substrata with a surface free energy around 55 erg cm-2. For each substratum, step 2 started after a characteristic time interval tau, being short (30 min) for gamma s less than 50 and long (120 min) for gamma s greater than 50 erg cm-2. The relationship between the substratum surface free energy and the number of bacteria adhering at equilibrium after step 2 was similar to, although less distinct than, that during step 1 with a slight indication of a bioadhesive minimum around gamma s = 35 erg cm-2. The results are indicative of a two-step adhesion model, in which step 1 is controlled by macroscopic substratum properties.     

设施调温模式下叶施低浓度NaCl对黄瓜幼苗生长和生理指标的影响

为了明确设施调温模式下叶施低浓度NaCl对黄瓜幼苗生长和物质积累的影响,本试验在日光温室内加设地膜小棚进行调温,形成中低温(L)区和中高温(H)区,采用0(L0和H0)、5(L5和H5)、10(L10和H10)、15 mmol-L-l(L15和H15)的NaCl 对2子叶1 心期的黄瓜幼苗进行连续21 d的叶面喷洒处理...     

The magnetic and electronic properties of Methanobacterium thermoautotrophicum (strain delta H) methyl coenzyme M reductase and its nickel tetrapyrrole cofactor F430. A low temperature magnetic circular dichroism study

Variable temperature magnetic circular dichroism (MCD) spectroscopy has been used to characterize the magnetic and electronic properties of the Ni(II) tetrapyrrole, F430, which is the cofactor of the S-methyl coenzyme M methylreductase enzyme from Methanobacterium thermoautotrophicum (strain delta H). 4-Coordinate forms are found to be diamagnetic (S = 0 ground state), whereas 6-coordinate forms are paramagnetic (S = 1 ground state). MCD studies, together with parallel low temperature UV-visible absorption and resonance Raman investigations, show that the equilibrium distribution of 4-coordinate square-planar and 6-coordinate bis-aquo forms of the native isomer of F430 in aqueous solution is affected by both temperature and the presence of glycerol. In the presence of 50% glycerol, the 12,13-diepimer of F430 is shown to be partially 6-coordinate in frozen solution at low temperature. Low temperature MCD magnetization data allow the determination of the axial zero-field splitting (D) of the S = 1 ground state of bis-ligand complexes of F430. The value of D is sensitive to the nature of the Ni(II) axial ligands: bis-aquo F430, D = +9 +/- 1 cm-1; bis-imidazole F430, D = -8 +/- 2 cm-1. Measurement of D = +10 +/- 1 cm-1 for F430 in the methylreductase holoenzyme argues strongly against histidine imidazole coordination to Ni(II) in the enzyme. The possible existence of alcoholic or phenolic oxygen-containing ligands (serine, threonine, tyrosine, water) to Ni(II) in the enzyme-bound cofactor is discussed.     

Physicochemical characterization of Rhesus low density lipoproteins.

The serum low density lipoprotein (LDL; p 1.019-1.050 g/ml) of the normal Macaca mulatta monkey (rhesus), kept on a low-fat Purina primate chow diet, was isolated by ultracentrifugal flotation, and its physicochemical properties were compared with those previously reported for human LDL. Rhesus LDL was found to be chemically similar to human LDL. The values for the sedimentation (S25, w-O) and diffusion (D25,w-O) coefficients were 7.09 S and 2.50 times 10- minus-7 cm-2 sec- minus-1, respectively. The intrinsic viscosity was 3.40 ml g- minus-1. The partial specific volume of rhesus LDL, determined in an Anton Paar precision density meter, was 0.960 ml g- minus-1. Molecular weights, calculated from a combination of S-O and D-O and of S-O and [n], were in agreement with the weight-average molecular weight, Mw, of 2.29 times 10-6 obtained by high-speed sedimentation equilibrium. In addition, a Z-average molecular weight, Mz, of 2.73 times 10-6 was calculated because curvature in the graphs of log c vs. r-2 indicated that rhesus LDL was heterogeneous. From the frictional ratio of 1.02, a maximum hydration of 0.1 g of H2O/g of lipoprotein was obtained. On electron micrographs, rhesus LDL appeared spherical with a mean diameter of 196 A, which was substantiated by hydrodynamic analysis.     

Photochemistry in dried polymer films incorporating the deionized blue membrane form of bacteriorhodopsin.

The preparation and photochemical properties of dried deionized blue membrane (dIbR600; lambdamax approximately 600 nm, epsilon approximately 54, 760 cm-1 M-1, f approximately 1.1) in polyvinyl alcohol films are studied. Reversible photoconversion from dIbR600 to the pink membrane (dIbR485; lambdamax approximately 485 nm) is shown to occur in these films under conditions of strong 647-nm laser irradiation. The pink membrane analog, dIbR485, has a molar extinction coefficient of approximately 39,000 cm-1 M-1 (f approximately 1.2). The ratio of pink --> blue and blue --> pink quantum efficiencies is 33 +/- 5. We observe an additional blue-shifted species (dIbR455, lambdamax approximately 455 nm) with a very low oscillator strength (f approximately 0.6, epsilon approximately 26,000 cm-1 M-1). This species is the product of fast thermal decay of dIbR485. Molecular modeling indicates that charge/charge and charge/dipole interactions introduced by the protonation of ASP85 are responsible for lowering the excited-state all-trans --> 9-cis barrier to approximately 6 kcal mol-1 while increasing the corresponding all-trans --> 13-cis barrier to approximately 4 kcal mol-1. Photochemical formation of both 9-cis and 13-cis photoproducts are now competitive, as is observed experimentally. We suggest that dIbR455 may be a 9-cis, 10-s-distorted species that partially divides the chromophore into two localized conjugated segments with a concomitant blue shift and decreased oscillator strength of the lambdamax absorption band.     

Toxic and cytogenetic effects induced in Allium cepa with low concenrations of Cd and 232th

232Th (7.76 x 10(-7) M) and Cd (0.89 x 10(-8) M) in concentrations which do not exceed officially prescribed standards when entering with water do not increase the frequency of chromosome aberrations in comparison with the control. Such concentrations do not cause toxic effects in plants on the levels of tissues and of the whole organism but they do display their activity on the cell level damaging division spindle. Dependence "cadmium concentration-effect" is not linear for any type of cytogenetical damages. At the concentration of cadmium 0.89 x 10(-7) M its influence on formation of division spindle is weakened and the frequency of chromosome aberrations is reducing in comparison with the control and with the effects induced at lower concentrations of cadmium in solution (0.89 x 10(-8) M). Cadmium in high concentration (5.34 x 10(-5) M) causes significant toxic and mutagenic effects.     

Romanowsky dyes and Romanowsky-Giemsa effect. 2. Eosin Y, erythrosin B, tetrachlorofluorescein, spectroscopic characterization of pure dyes, association of eosin Y

Analytically pure samples of the Romanowsky dyes eosin y, erythrosin b and tetrachlorofluorescein are prepared. DC of the dye samples shows no contaminations. We measured the absorption spectra of the dye dianions in alkaline aqueous solution and of the dye acids in 95% ethanol at very low dye concentrations. The molar extinction coefficients of the long wavelength absorption of the monomeric dye species are determined (Table 1). The extinction coefficients may be used for standardisation of dye samples. The absorption spectra of eosin y in aqueous solution are dependent on concentration. Using a new very sensitive method it was possible to identify two association equilibria from the concentration dependency of the spectra. Dimers are formed even in very dilute solutions, at higher concentrations tetramers. The dissociation constant of the dimers D in monomers M at 293 K, pH = 12, is K21 = 2,9 X 10(-5) M; of the tetramers Q in dimers D K42 = 2,4 X 10(-3) M. From the experimental spectra of eosin solutions at various concentrations, pH = 12, and the equilibrium constants K21, K42 the absorption spectra of the pure monomers, dimers and tetramers are calculated. M has one long wavelength absorption band, VM = 19300 cm-1, epsilon M = 1,03 X 10(5) M-1 cm-1; D also one absorption band, VD = 19300 cm-1, epsilon D = 1,74 X 10(5) M-1 cm-1; Q two absorption bands, VQ1 = 19100, VQ2 = 20200 cm-1, epsilon Q1 = 1,65 X 10(5), epsilon Q2 = 1,96 X 10(5) M-1 cm-1. The absorption spectrum of the dimers is discussed by quantum mechanics.     

Sodium cloprostenol administered at a continuous low dosage induces polydipsia and suppresses luteal function in early dioestrous bitches.

The aim of this study was to determine whether sodium cloprostenol administered at a continuous low dosage induced luteolysis and polydipsia in early dioestrous bitches. Sodium cloprostenol was administered subcutaneously to greyhounds at doses of 4.04-5.19 microg/kg/day (treated group, n=5) or 0 microg/kg/day (control group, n=5) delivered by mini-osmotic pumps for 7 days. The treated bitches and two of the control bitches were in early dioestrus (Days 5-14, and 6 and 10, respectively) when the mini-osmotic pump was inserted (Day 0). Concentrations of plasmatic progesterone were measured in dioestrous bitches each day from Day -2 to 7, and then weekly until Day 90. Daily intake of water was ascertained in all bitches from Day -2 until Day 10, and their weight was measured on Days -2, 6 and 13. Biochemical analyses on plasma for concentrations of urea and glucose, and urinalyses were performed on all bitches before (Day -1), during (Day 4) and after treatment (Day 10). Concentrations of plasmatic progesterone declined dramatically and rapidly in treated bitches after Day 0 to <2.9 ng/ml but were not similarly affected in the dioestrous control bitches. However, in three of five treated bitches, concentrations of plasmatic progesterone increased to >1 ng/ml in the period from Day 10 to 90 indicating that luteolysis was incomplete. All treated bitches were polydipsic (intake of water >100 ml/kg/day) for 2-6 days during the period of treatment, and for 0-2 days immediately after treatment (Days 7 and 8). One control bitch was polydipsic on Days -2, -1 and 0. The treated bitches were also polyuric since they were hyposthenuric (<1.007, n=4) or isothenuric (1.010, n=1) on Day 4, their weight did not increase and no gastrointestinal or respiratory effects were observed. The control bitches were always hypersthenuric when measured during and after treatment (>1.021). Biochemical analyses of plasma and other data obtained from urinalyses did not reveal any differences between groups. This study indicated that sodium cloprostenol administered at a continuous low dosage induced polydipsia and suppressed luteal function in early dioestrous bitches.