Polarography of disodium pentacyanonitrosylferrate(II): Part 2. Determination at Therapeutic Levels in Serum,Plasma, and Whole Blood

Disodium pentacyanonitrosylferrat(II) (sodium nitroprusside) is determined at therapeutic (ng ml^?1) levels in plasma, serum and blood with conventional and high-performance differential pulse polarography (d.p.p. and h.p.d.p.p.) at a dropping mercury electrode or a static mercury drop electrode. Serum or plasma (3 ml) is treated with perchloric acid containing 1 mg ml^?1 potassium hexacyanoferrate(II), centrifuged for 10 min and subjected to polarography. For spiked serum, calibration graphs are linear over the range 30–1000 ng ml^?1 sodium nitroprusside, regardless of the polarographic technique; the estimated detection limit is 15 ng ml^?1 (5 × 10^?8 M). Calculated therapeutic levels range from 100 to 1000 ng ml^?1. Similar results were obtained for spiked plasma. A similar procedure is suitable for whole blood and was used to study the in-vitro degradation of sodium nitroprusside (200 ng ml^?1) on incubation at 37°C. The in-vitro loss is rapid (t_{$\text{1}\text{2}$} ≈ 6 min) but meaningful in-vivo levels can be obtained when the blood is collected in a 0.9% sodium chloride solution at 0°C. Thiocyanate, the main metabolite of nitroprusside, and thiosulphate, which is a potential antidote for cyanide, do not interfere.     

Studies in organic mass spectrometry. XXII–Evidence for the existence of cyclic oxonium ions in the gas phase

The electron impact induced loss of a phenoxy radical from the molecular ions of α,ω-bis-aryloxy alkanes ΦO(CH₂)_nOΦ ( 1 _n; n = 2–7) and F-p-C₆H₄(CH₂)_nOΦ(2_n; n = 2?5) is the result of functional group interaction. Labelling data provide conclusive evidence for the O-aryl tetra-hydrofuranium and O-aryl tetrahydropyranium structures of the resulting decomposing species (lifetimes between 10^?6 and 10^?5 s) in the case of n = 4 and 5, respectively. Evidence is presented for the occurrence of phenyl participation in the loss of ΦOH from the molecular ions of the lower homologues of 1 _n and 2_n (n = 2, 3).     

Sequence selective recognition in the minor groove of dsDNA by pyrrole,imidazole-substituted bis-benzimidazole conjugates

A series of pyrrole, imidazole-substituted bis-benzimidazole conjugates, Py-Py-Im-gamma-biBenz, Py-Py-gamma-biBenz, Py-Im-gamma-biBenz, and Im-Py-gamma-biBenz (1-4), were prepared in an attempt to target dsDNA sequences possessing both A/T and G/C bps. The dsDNA interactions and sequence specificity of the conjugates have been characterized via spectrofluorometric titrations and thermal melting studies. All conjugates form 1:1 complexes with dsDNA at subnanomolar concentrations. The Im moiety selectively recognizes a G/C bp embedded in the A/T-rich binding site. This represents the first clear example of sequence selective recognition in a 1:1 motif.(1) The equilibrium association constant (K(1)) for complexation of a specific nine-bp dsDNA site, 5'-gcggTATGAAATTcgacg-3', by conjugate 1 is approximately 2.6 x 10(9) M(-1). Displacement of the G/C position or G/C-->A/T substitution within the nine-bp site decreases the K(1) by approximately 8-fold, whereas two continuous G/C bps decrease the K(1) by approximately 50-fold magnitude. The K(1) values for seven-bp dsDNA, 5'-gcggtaTGAAATTcgacg-3' and 5'-gcggtaCAAAATTcgacg-3', binding sites by conjugates Py-Im-gamma-biBenz (3) and Im-Py-gamma-biBenz (4) are approximately 2.3 x 10(9) and approximately 1.2 x 10(9) M(-1), respectively. However, the conjugates with no Im moiety, Py-Py-gamma-biBenz (2) and Py-Py-Py-gamma-biBenz (5 and 6), are specific for seven- to nine-bp A/T-rich sites and single A/T-->G/C bp substitution within the binding site decreases the K(1) values by 1-2 orders of magnitude.     

Photodynamic properties of amphiphilic derivatives of aluminum tetrasulfophthalocyanine

Photodynamic therapy (PDT) is a promising treatment modality that has recently been accepted in clinics as a curative or palliative therapy for cancer and other nonmalignant conditions. Phthalocyanines (Pc) are attractive photosensitizers for PDT because of their enhanced photophysical and photochemical properties. The overall charge and solubility of Pc play a major role in their potential usefulness for PDT. A series of amphiphilic derivatives of tetrasulfonated aluminum Pc (AlPcS4) was prepared by substituting one of the four sulfonate groups with aliphatic side chains of 4, 8, 12 and 16 carbon atoms. The photodynamic properties of the derivatives were compared with those of AlPcS4 and the adjacent disulfonated aluminum Pc. Parameters studied included reversed-phase high-performance liquid chromatography (HPLC) retention times, capacity to generate singlet oxygen (1O2), in vitro cell uptake and phototoxicity, as well as PDT response of transplantable EMT-6 tumors in mice. The monomerized AlPcS4 derivatives showed similar or higher capacities to generate 1O2 as compared with the parent AlPcS4 as measured from relative L-tryptophan photooxidation yields. A549 cell uptake of the AlPcS4 derivatives decreased in the following order: AlPcS4(C16) > AlPcS4(C12) > AlPcS4(C8) > AlPcS4(C4). Human low-density lipoprotein at high concentrations (40 micrograms/mL) completely prevented uptake, whereas at 4 micrograms/mL uptake was decreased for the more lipophilic compounds and yet remained unaffected for the more hydrophilic dyes. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, A549 cell survival was assessed; it showed that photocytotoxic activity varied directly with the HPLC retention times, i.e. more hydrophilic compounds were less phototoxic. As 1O2 yields were similar for the four substituted AlPcS4 derivatives, it was postulated that the increased cytotoxic activity was caused by enhanced subcellular localization as a result of the long aliphatic side chains. These amphiphilic compounds proved to be photodynamically potent against the EMT-6 mouse mammary tumor model implanted in Balb/c mice. At dye doses of 0.2 mumol/kg and a fluence of 400 J/cm2 complete tumor regression was observed with no morbidity. The substitution of AlPcS4 with long aliphatic chains on the macrocycle greatly enhances its photodynamic efficacy both in vitro and in vivo.     

Gas chromatography-mass spectrometry as a tool for estimating odour concentrations of biofilter effluents at aerobic composting and rendering plants

The relationship between chemical concentrations (gas chromatography–mass spectrometry analysis) and odour concentrations (olfactometry) was studied for biofilter emissions from four aerobic vegetable, fruit and garden waste (VFG) composting plants and one animal rendering plant. For the VFG composting plants, the study revealed a good linear relationship of the odour concentration with the total volatile organic compounds (VOC) concentration (R²=0.97, n=16) as well as with the concentration of esters and ketones (R²=0.9, n=19). For biofilter emissions of the animal rendering plant, the total VOC concentration was a poor estimator for odour concentration. However, for this type of odour, concentrations of organic sulphur containing compounds correlated well with odour concentrations (R²=0.94, n=8). The results of the study also showed that the relationship between chemical and odour concentrations is specific for each type of odour and cannot be generalized.     

PRODUCTION OF BREAKS IN SINGLE- AND DOUBLE-STRANDED FORMS OF BACTERIOPHAGE øx174 DNA BY PROFLAVINE AND LIGHT TREATMENT

Abstract— Irradiation at 440 + 360 nm and a fluence rate of 3.8 kJm^-2 min^-1, of both complexes previously formed between proflavine and either øX circular single-stranded (ss) DNA or øX supercoiled duplex (RFI)DNA, induces single-strand scissions in the two DNAs under consideration. Linear øXSS DNA molecules are detected by sedimentation through alkaline sucrose gradients. After treatment of the øXRFI DNA, however, the degree of degradation is the same whether it is measured under neutral or alkaline conditions, indicating that alkaline-labile bonds are not created; moreover, double-strand breaks can only be detected after accumulation of single-strand breaks. In addition to the amount of proflavine bound to the DNA and the duration of irradiation, the following factors are shown to influence the nicking activity of the treatment: (1) the DNA structure (the øXRFI DNA is much more sensitive than the øXss DNA); (2) the ionic strength of the medium during irradiation (a high value of 0.5 leads to a markedly increased efficiency); (3) the addition of cysteamine (this latter compound decreases the reaction rate) and (4) the irradiation wavelength (after irradiation at 440 nm alone, the reaction occurs at a reduced rate and is sensitive to NaN₃). The kinetics of the nicking reaction does not follow a single-hit curve showing that at least one primary lesion occurs prior to strand breakage. On the other hand, strand scission cannot be detected after irradiation of the proflavine-DNA complexes at the low fluence rate causing a decrease in the infectivity of both øXSS and øXRFI DNAs. Similarly. the sedimentation pattern of the DNA extracted from treated øx174 phages 99.9% inactivated, is identical to that of the control ss DNA, although more drastic treatments are susceptible to induce single strand breaks inside the phage head. Finally, the unknown lesion (s) that is biologically important does not prevent the treated DNAs from penetrating into the hostcells.     

Zur Kennzeichnung der Lorentz-Transformationen

Let (V, f) be a real Minkowski space of any, not necessarily finite, dimension, and letd be the corresponding distance function (taking negative values for timelike distances). Then the following statement (among others) is proved: If ? :V →V is a surjective mapping such that $$d(P,Q) = a \Leftrightarrow d(P^\varphi ,Q^\varphi ) = a\forall P,Q \in V$$ is true for some fixeda εR,a<0, then ? is a Lorentz transformation (including a possible translation).     

On the asymptotic approximations of the solutions of a system of two non-linearly coupled harmonic oscillators

A procedure, closely related to the averaging method, is given for the construction of asymptotic approximations for the solutions of the Lagrangian system

$\text{d}\text{x}{}_1\text{d}\text{t}\text{=x}{}_2\text{,}\text{d}\text{x}{}_2\text{d}\text{t}\text{=?x}{}_1\text{+ε}\text{∑}\text{i, j=1}\text{4}\text{α}{}_{\mathrm{ij}}\text{x}{}_{\mathrm{i}}\text{x}{}_{\mathrm{j}}\text{,}\text{d}\text{x}{}_3\text{d}\text{t}\text{=x}{}_4\text{,}\text{d}\text{x}{}_4\text{d}\text{t}\text{=?4(1+δ)x}{}_3\text{+ε}\text{∑}\text{i, j=1}\text{4}\text{β}{}_{\mathrm{ij}}\text{x}{}_{\mathrm{i}}\text{x}{}_{\mathrm{j}}\text{, x}{}_1\text{(0)=a}{}_0\text{, x}{}_2\text{(0)=0, x}{}_3\text{(0)=b}{}_0\text{, x}{}_4\text{(0)=0,}$

where ε > 0 and δ > 0 are small parameters, a_ij = a_ji and β_ij = β_ji are real constants. The solutions can be represented as follows:

$\text{x}{}_1\text{=a}\text{cos}\text{(t+ξ), x}{}_2\text{=a}\text{sin}\text{(t+ξ), x}{}_3\text{=b}\text{cos}\text{(2t+ψ), x}{}_4\text{=2b}\text{sin}\text{(2t+ψ).}$

The asymptotic approximations (in a certain well-defined sense) of a, b, ξ and ψ are given. It is shown that a rapid variation of the phase, ψ(t), will take place if b → 0 for the case that δ ≈ ε or δ ? ε. In addition for the case δ ≈ ε the phenomenon of bifurcation will be discussed.     

Study of the Physicochemical and Biological Properties of the Lipid Complex of Marine Microalgae Isolated from the Coastal Areas of the Eastern Water Area of the Baltic Sea

The Baltic Sea algae species composition includes marine euryhaline, freshwater euryhaline, and true brackish water forms. This study aimed to isolate a lipid–pigment complex from microalgae of the Baltic Sea (Kaliningrad region) and investigate its antimicrobial activity against Gram-positive and Gram-negative bacteria. Microalgae were sampled using a box-shaped bottom sampler. Sequencing was used for identification. Spectroscopy and chromatography with mass spectroscopy were used to study the properties of microalgae. Antibiotic activity was determined by the disc diffusion test. Lipids were extracted using the Folch method. Analysis of the results demonstrated the presence of antimicrobial activity of the lipid–pigment complex of microalgae against E. coli (the zone diameter was 17.0 ± 0.47 mm and 17.0 ± 0.21 mm in Chlorella vulgaris and Arthrospira platensis, respectively) and Bacillus pumilus (maximum inhibition diameter 16.0 ± 0.27 mm in C. vulgaris and 16.0 ± 0.22 mm in A. platensis). The cytotoxic and antioxidant activities of the lipid complexes of microalgae C. vulgaris and A. platensis were established and their physicochemical properties and fatty acid composition were studied. The results demonstrated that the lipid–pigment complex under experimental conditions was the most effective against P. pentosaceus among Gram-positive bacteria. Antimicrobial activity is directly related to the concentration of the lipid–pigment complex. The presence of antibacterial activity in microalgae lipid–pigment complexes opens the door to the development of alternative natural preparations for the prevention of microbial contamination of feed. Because of their biological activity, Baltic Sea microalgae can be used as an alternative to banned antibiotics in a variety of fields, including agriculture, medicine, cosmetology, and food preservation.