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I Svoboda

Publications and source records attributed to I Svoboda.

At least 19 recordsLinked to original sources
PubMed2001

(Bis(N,N-dimethylformamide)[mu-N,N'-bis(salicylidene)-1,3-propanediaminato]nickel(II))dibromozinc(II).

The title compound, [NiZnBr2(C3H7NO)2(C17H16N2O2)], is a heterodinuclear nickel complex. The Ni atom has an irregular octahedral environment involving two O and two N atoms from the bis(salicylidene)-1,3-propanediaminate ligand in the equatorial plane, and two O atoms from the dimethylformamide groups. The Zn-O-Ni, O-Zn-O, Ni-O-Zn and O-Ni-O angles in the bridged plane are 100.1 (2), 79.9 (2), 100.4 (2) and 78.89 (17) degrees, respectively. The Ni...Zn distance is 3.0738 (19) A

Journal Article↗
PubMed2001

(Bis[2-(2-oxido-1-naphthylmethylideneamino)phenyl]disulfide)chloroiron(III).

The crystal structure of the title compound, (bis[2-(2-oxido-2-naphthylideneamino)phenyl] disulfide-kappa(5)O,N,S,N',O')chloroiron(III), [FeCl(C(34)H(22)N(2)O(2)S(2))], has been determined. The structure consists of monomeric iron(III) complexes with distorted octahedral coordination. The disulfide functions as a pentadentate ligand and the Fe(III) atom is coordinated through two N, two O and one S atom, and one chloride ion. The distance between the second S atom and the Fe(III) atom is a non-bonding 3.8473 (14) A.

Journal Article↗
PubMed2001

5-Chloro-N-(2-hydroxy-5-methylphenyl)salicylaldimine.

The title compound, N-(5-chloro-2-oxidobenzylidene)-2-hydroxy-5-methylanilinium, C(14)H(12)ClNO(2), is a tridentate Schiff base with almost planar molecules. Each molecule contains a strong intramolecular N-H.O hydrogen bond [2.576 (2) A]. There is also an intermolecular O-H.O hydrogen bond [2.695 (2) A] linking neighbouring molecules into infinite chains along the [101] direction.

Journal Article↗
PubMed2000

Selective imidazolidine ring opening during complex formation of iron(III), copper(II), and zinc(II) with a multidentate ligand obtained from 2-pyridinecarboxaldehyde N-oxide and triethylenetetramine.

The condensation of 2-pyridinecarboxaldehyde N-oxide and triethylenetetramine yields a product with two imidazolidine rings, as proven by a solid-state X-ray structure analysis as well as by NMR solution spectra. This ligand, L1, undergoes a ring-opening reaction on complex formation with Cu(II), yielding [CuL2]2+ where L2 functions as a pentadentate ligand, containing only one imidazolidine ring. On complexation with Zn(II) and Fe(III), both rings are opened and the complexes [ZnL3]2+ and [FeL3]3+ with a hexadentate L3 ligand are formed. The recrystallization of [ZnL3]2+ from DMSO solution results in the complex [ZnL1(DMSO)2]2+ in which L1 behaves as a tetradentate ligand. Thus L1, L2, and L3 are structural isomers with two, one, or no imidazolidine rings, as confirmed by X-ray structure analyses. The intramolecular ring formation is the result of the nucleophilic addition of the N(amino) group to the electrophilic sp2-hybridized -HC delta+=N site. Owing to the absence of the chelate effect on the sp3-hybridized carbon atom belonging to the imidazolidine ring, the ring opening is facilitated and readily observed upon complex formation with Cu(II), Zn(II), and Fe(III).

Journal Article↗
PubMed2000

2-

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Journal Article↗
PubMed2000

A complex containing both five- and six-coordinate

The title compound, aquachloro4,4'-dibromo-2, 2'-[o-phenylenebis(nitrilomethylidyne)]diphenolato-O,N,N', O'iron(III)-chloro4,4'-dibromo-2, 2'-[o-phenylenebis(nitrilomethyli-dyne)]diphenolato-O,N,N', O'iron(III)-dimethylformamide (1/1/1), [FeCl(C(20)H(12)Br(2)N(2)O(2))][FeCl(C(20)H(12)Br(2)N(2)O(2))(H(2)O)] .C(3)H(7)NO, contains one independent five-coordinate [FeCl(C(20)H(12)Br(2)N(2)O(2))] monomer, one six-coordinate [FeCl(C(20)H(12)Br(2)N(2)O(2))(H(2)O)] monomer and a non-coordinating dimethylformamide solvent molecule in the asymmetric unit. In the five-coordinate monomer, the Fe atom shows distorted square-pyramidal geometry, with the N and O atoms of the ligand at the base and the Cl atom at the apex of the pyramid. In the six-coordinate monomer, the Fe atom is in a distorted octahedral geometry and coordinated by the donor atoms of the tetrafunctional ligand in the horizontal plane, and the coordination sphere is completed by the O atom of the water molecule and the Cl atom at the axial positions. The title compound contains intermolecular O-H.O hydrogen bonds. Apart from these hydrogen bonds, there are also intermolecular C-H.Cl and C-H.O contacts.

Journal Article↗
PubMed2000

[N,N'-Bis(5-bromosalicylidene)-1,3-diaminopropane]nickel(II) and [N, N'-bis(5-chlorosalicylidene)-1,3-diaminopropane]copper(II).

The title compounds, ¿4,4'-dibromo-2,2'-[1, 3-propanediylbis(nitrilomethylidyne-N)]diphenolato-O,O '¿nickel(II), [Ni(C(17)H(14)Br(2)N(2)O(2))], and ¿4,4'-dichloro-2,2'-[1, 3-propanediylbis(nitrilomethylidyne-N)]diphenolato-O,O '¿copper(II), [Cu(C(17)H(14)Cl(2)N(2)O(2))], lie on crystallographic twofold axes. In both structures, the metal coordination sphere is a tetrahedrally distorted square plane formed by the four-coordinate N(2)O(2) donor set of the Schiff base imine-phenol ligands. In the Ni compound, the Ni-O and Ni-N distances are 1.908 (3) and 1.959 (4) A, respectively, while in the Cu compound, the Cu-O and Cu-N distances are 1.907 (2) and 1.960 (2) A, respectively. The two Schiff base moieties, which themselves are nearly planar, are inclined at an angle of 29.26 (7) degrees for the Ni compound and 29.26 (5) degrees for the Cu compound.

Journal Article↗
PubMed2000

[N,N'-bis]

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Journal Article↗
PubMed2000

The fate of Escherichia coli and E. coli O157 in cattle slurry after application to land.

The fate of both faecal Escherichia coli and E. coli O157 in slurry following application to arable and grass plots on a clay loam soil was studied. Slurry (5% dry matter) containing 5.3 x 10(4) ml(-1) E. coli and 30 E. coli O157 100 ml(-1) was spread in early March. Initially, almost all E. coli were retained in the upper layers of the soil. Escherichia coli numbers steadily declined to less than 1% of those applied by day 29, and E. coli O157 were only detected in the soil and on the grass for the first week after application. There was some transport of bacteria to deeper layers of the soil, but this was approximately 2% of the total; transport to drains over the same period was mainly associated with rainfall events and amounted to approximately 7% of applied E. coli. However, there were indications that periods of heavy rainfall could cause significant losses of E. coli by both leaching and run-off. Experimental studies showed that E. coli O157 on grass, which was subsequently ensiled in conditions allowing aerobic spoilage, could multiply to numbers exceeding 10(6) g(-1) in the silage.

Animals↗
PubMed1996

Induction effects of polychlorinated biphenyls, polycyclic aromatic hydrocarbons and other widespread aromatic environmental pollutants on microsomal monooxygenase activities in chick embryo liver.

Cytochrome P450-dependent 7-ethoxyresorufin O-deethylase (EROD), 7-pentoxyresorufin O-dealkylase (PROD) and 7-ethoxycoumarin O-deethylase (ECOD) activities in 14-day-old chick embryo livers were determined 24 h after pretreatment with selected widespread aromatic environmental contaminants, including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), hexachlorobenzene, and dialkylesters of phthalic acid, and compared with the inducing potencies of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and the coplanar and mono-o-chlorinated PCBs. The effects of other model inducers, i.e. phenobarbital and pyrazole, were also examined. Specificity of EROD induction was estimated with regard to contaminants frequently present in environmental samples and dose-response curves for EROD induction were determined. A strong induction (comparable with that by mono-o-chlorinated biphenyl treatment) by dibenzo[a,h]anthracene, benzo[k]fluoranthene or benzo[b]fluoranthene was found, but the maximal level of EROD activity inducible by TCDD was not achieved, partly due to the high toxicity of the tested PAHs. 3-Methylcholanthrene showed moderate inducing potencies; benz[a]anthracene, benzo[a]pyrene, chrysene and 2,2',3,4,4',5'-hexachlorobiphenyl appeared to be weak inducers. Other PAHs and PCBs tested, as well as hexachlorobenzene, dialkyl phthalates, phenobarbital and pyrazole had no marked effects on the EROD level. ECOD activities were increased non-specifically by TCDD, 3-methylcholanthrene, hexachlorobenzene and phenobarbital. A significant enhancement of PROD activity by TCDD and related inducers was observed, while phenobarbital induced the PROD activity only weakly; SDS-PAGE analysis showed that the chicken phenobarbital-inducible cytochromes P4502H with apparent molecular weights 50 kDa were not markedly induced by the TCDD- or 3-methylcholanthrene treatments. Inhibition of EROD and PROD by 9-hydroxyellipticine, a specific inhibitor of rat hepatic cytochrome P4501A1, revealed that PROD induction by TCDD and other P4501A-inducers was probably a result of a broader substrate specificity of chick embryo P4501A. Measurement of EROD activities in chick embryo liver is highly sensitive, specific and suitable for the determination of TCDD-type toxicity of new drugs, agrochemicals, and industrial pollutants.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1994

Semisynthetic insulin analogues modified in positions B24, B25 and B29.

New semisynthetic analogues of human insulin, modified in the C-terminal region of the B-chain, were prepared to refine our understanding of the importance of particular amino acid residues in the expression of hormone biological properties. The following insulin analogues were synthesized by trypsin-catalyzed peptide-bond formation between the C-terminal arginineB22 of des-octapeptide(B23-B30)-insulin and synthetic octapeptides with the epsilon-amino group of lysineB29 protected by a phenylacetyl group: [L-Lys(Pac)B29]insulin, [D-PheB24,B25,L-Lys(Pac)B29]insulin and [D-Phe(p-Et)B24, L-Lys(Pac)B29]insulin. Enzymatic deprotection using immobilized penicillin amidohydrolase yielded: human insulin, [D-PheB24,B25]insulin and [DPhe(p-Et)B24]-insulin. Biological in vitro potencies (specific binding to cultured human lymphocytes IM-9 and lipogenic potency in isolated rat adipocytes) of the semisynthetic analogues were estimated, ranging from 0.2 to 100% relative to porcine insulin.

Adipocytes↗
PubMed1986

[Experimental and natural infection with the enzootic leukosis virus of cattle].

A trial was performed with heifers at the age of six to seven months. The animals were experimentally infected with the lymphocytes of a virus-productive donor. Infection was produced in all the nine cases, as demonstrated by means of the positive syncytial test. As indicated by the results of the trial, the antibodies to the enzootic bovine leucosis virus (BLV) were produced soon after experimental infection. A high sensitivity of the serum-neutralization test and the ELISA method was demonstrated in this connection: by these methods, the antibodies were identified already two to three weeks after experimental infection whereas by the immunodiffusion test they could be detected only after five weeks. Twenty-four animals were exposed to natural contact infection. Within 270 days of the trial, the disease after contact was recorded only in one heifer out of the four that were in close contact with the experimentally infected animals. In this case, as compared with experimental infection, the antibodies were produced much later--after 85 to 93 days. Leucosis was recorded in none of the remaining animals. The reasons why such a favourable result was obtained were the thorough disinfection of the stables after blood collections and the strict observance of the aseptic conditions. The results of experimental infection in three cows were identical with those obtained in young cattle. In the experimentally infected dairy cows, antibodies in milk were determined by the ELISA method. As found, in milk the antibodies to BLV appear two to three weeks later than they do in serum. The ELISA method of BLV antibody detection can be used for the identification of infected animals in herds where enzootic bovine leucosis occurs.

Animals↗
PubMed1986

[Detection of bovine leukemia virus antibodies using the cytotoxicity test in comparison with other serologic methods].

In ninety-five serum samples taken in a herd of five-year to seven-year cattle that was heavily infected by bovine leukosis virus, the four serological assays were used for demonstration of the antibodies to bovine leukosis virus; cytotoxic test, immunodiffusion test in agar-agar, immunoenzymatic test and serum neutralizing test. The serum neutralizing test was found to be the most sensitive: further seven positive reagents were diagnosed in comparison with immunoenzymatic test; cytotoxic and immunodiffusion tests in agar-agar have the lowest sensitivity and the results of these tests are almost identical. It was found out in forty titrated samples that serum neutralizing test was by as much as 20 times more sensitive than immunoenzymatic test, the latter being about 50 times more sensitive than cytotoxic and immunodiffusion tests.

Antibodies, Viral↗
PubMed1986

[Radioimmunologic detection of antibodies to bovine leukemia virus].

The radioimmunologic assay (RIA) was elaborated for a demonstration of serum antibodies to bovine leukosis virus. The procedure makes use of the viral antigen bond to the fixed phase of a polystyrene carrier. The method was compared with the ELISA method and pseudoneutralizing and immunodiffusion tests. High congruence of the results of the RIA and ELISA methods was achieved, making 95%. The RIA method is more sensitive than the immunodiffusion test.

Antibodies, Viral↗
PubMed1986

[Differential diagnosis of viral diarrheas in calves].

There is a description of the enzymoimmunologic method (ELISA), which was used for demonstration of rotaviruses and coronaviruses in the samples of excrements of the calves suffering from diarrheas. It is shown by a comparison with the results obtained by electron microscopy that the ELISA method provides by up to 50% higher capture rate and the reaction is highly specific. The method can also be applied to a detection of human rotavirus in the children's stool.

Animals↗