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Biomedical subjects

M Klich

Publications and source records attributed to M Klich.

13 recordsLinked to original sources
PubMed2003

Trace element contamination in industrial regions of Poland studied by moss monitoring.

The use of terrestrial mosses as biomonitors in large-scale multi-element studies of heavy metal deposition from the atmosphere is a well established technique in Europe. In such studies it is advantageous to determine as many elements as possible in order to distinguish between different source categories. A combination of INAA and AAS has been found very useful in this respect, in particular when epithermal activation is used for instrumental neutron activation analysis. A total of 33 elements (Al, Cl, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Ag, Cd, Sb, I, Cs, Ba, La, Ce, Tb, Yb, Hf, Ta, W, Au, Pb, Th, and U) in Pleurozium schreberi (Brid.) Mitt. moss samples from the Silesia-Kraków Industrial Region and Legnica-Głogów Copper Basin and from the control (background) area in Northeast Poland were identified. The highest concentrations of the majority of trace elements were found in mosses growing in the Silesia-Kraków Industrial Region, only Cu and As concentrations were higher in mosses in the Legnica-Głogów Copper Basin. These results are in conformity with the load of trace elements emissions in these areas.

Bryophyta↗
PubMed2003

Mycotoxins.

Mycotoxins are secondary metabolites produced by microfungi that are capable of causing disease and death in humans and other animals. Because of their pharmacological activity, some mycotoxins or mycotoxin derivatives have found use as antibiotics, growth promotants, and other kinds of drugs; still others have been implicated as chemical warfare agents. This review focuses on the most important ones associated with human and veterinary diseases, including aflatoxin, citrinin, ergot akaloids, fumonisins, ochratoxin A, patulin, trichothecenes, and zearalenone.

Aflatoxins↗
PubMed2001

Fine Tuning of physico-chemical parameters to optimise a new series of novobiocin analogues.

A novel series of novobiocin analogues has been synthesised by removing the lipophilic aryl chain in novobiocin and introducing an amino substituent. The structural modifications have been dictated by the control of lipophilicity and the dissociation constant of the resulting compounds. Antibacterial activity of the new coumarin derivatives could be correlated with the amount of uncharged form in physiological conditions.

Anti-Bacterial Agents↗
PubMed2001

A new sterigmatocystin-producing Emericella variant from agricultural desert soils.

An unusual, sterigmatocystin-producing taxon with characteristics of both Emericella nidulans (anamorph Aspergillus nidulans) and Emericella rugulosa (anamorph Aspergillus rugulovalvus, formerly A. rugulosus) was isolated repeatedly during a mycofloral survey of desert cotton field soils where aflatoxin is a chronic problem. Members of this taxon had ascospores with smooth convex walls like E. nidulans but grew slowly like E. rugulosa; moreover, they were similar to an industrial echinocandin B-producing strain which had been classified as "Aspergillus nidulans var. roseus." These new desert isolates were compared with "A. nidulans var. roseus" and representative wild-type isolates of E. nidulans and E. rugulosa using traditional morphological characters, secondary metabolite profiles of mycelial extracts, and Southern blot analysis of genomic DNA. The desert isolates and "A. nidulans var. roseus shared morphological, physiological and molecular characters with E. rugulosa. These isolates constitute a new non-rugulose variant of E. rugulosa.

Agriculture↗
PubMed2000

Improved antibacterial activities of coumarin antibiotics bearing 5',5'-dialkylnoviose: biological activity of RU79115.

A new series of coumarin inhibitors of DNA gyrase B bearing a N-propargyloxycarbamate at C-3' of various 5',5'-dialkylnoviose, including RU79115, were synthesised and their antibacterial activities have been delineated. Introduction of dialkyl substituents at 5'5'-position of noviose leads to coumarin analogues with improved in vitro and in vivo antibacterial activity.

Anti-Bacterial Agents↗
PubMed2000

Coumarin inhibitors of gyrase B with N-propargyloxy-carbamate as an effective pyrrole bioisostere.

The synthesis and biological profile in vitro of a series of coumarin inhibitors of gyrase B bearing a N-propargyloxycarbamate at C-3' of noviose is presented. Replacement of the 5-methylpyrrole-2-carboxylate of coumarin drugs with an N-propargyloxycarbamate bioisostere leads to analogues with improved antibacterial activity. Analysis of crystal structures of coumarin antibiotics with the 24 kDa N-terminal domain of the gyrase B protein provides a rational for the excellent inhibitory potency of C-3' N-alkoxycarbamates.

Anti-Bacterial Agents↗
PubMed2000

Territory acquisition in loons: the importance of take-over.

We examined patterns of territory acquisition and reconnaissance in common loons, Gavia immer, from northern Wisconsin. Among all territory acquisitions, 41.5% occurred through passive occupation of territories left vacant after the death or desertion of a previous resident, 17% constituted founding of new territories and the remaining 41.5% came about through take-over: either usurpation of defended territories or appropriation of territories before the seasonal return of previous owners. Take-overs occurred in both sexes, but individuals acted alone, never in pairs. Displaced breeders usually took refuge on undefended lakes near their former territories; about half of these loons later regained former territories through passive occupation or took possession of new territories elsewhere. As predicted by the reconnaissance hypothesis, usurpations occurred most often in territories that had produced chicks during the previous 12 months, suggesting that loons use the presence or absence of chicks as a cue for territorial usurpation. Large individuals of both sexes held onto territories longer than small individuals, an indication that body size might be correlated with fighting ability. In terms of life history, loons appear to locate good territories through reconnaissance, usurp them in a subsequent year and recover from displacements by reclaiming their original territories or new ones. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1999

Synthesis and biological evaluation of coumarincarboxylic acids as inhibitors of gyrase B. L-rhamnose as an effective substitute for L-noviose.

A series of novobiocin-like coumarincarboxylic acids has been prepared bearing the L-rhamnosyl moiety as the sugar portion of the molecule. The similar DNA gyrase inhibitory activity of the novel class of coumarins to that of novobiocin demonstrates that L-rhamnose can effectively replace L-noviose. Introduction of alkyl side-chains at C-5 of coumarin leads to improved in vitro antibacterial properties in the novel series.

Anti-Bacterial Agents↗
PubMed1999

Synthesis and in vitro evaluation of novel highly potent coumarin inhibitors of gyrase B.

The design, synthesis, and in vitro biological activity of a series of novel coumarin inhibitors of gyrase B is presented. Replacement of the 3-acylamino residue (3-NHCOR) of coumarin drugs with reversed isosteres C(=O)R, C(=N-OR)R', COOR, CONHR and CONHOR leads to highly potent analogues which displayed excellent inhibition of the negative supercoiling of the relaxed DNA and antibacterial activity.

Anti-Bacterial Agents↗
PubMed1996

Spring migratory birds (Aves) extend the northern occurrence of blacklegged tick (Acari:Ixodidae).

Birds that had migrated northward across Lake Superior were captured upon reaching landfall at Thunder Cape (48 degrees 18' N, 88 degrees 56' W) at the southwestern tip of the Sibley Peninsula, northwestern Ontario, from 9 May to 9 June 1995. Twenty-one of 530 birds examined (6 of 55 species) had a total of 34 ticks; 1 blue jay, Cyanocitta cristata, had a northern fowl mite, Ornithonyssus sylviarum (Canestrini & Fanzago). Four blacklegged tick, Ixodes scapularis Say, larvae were found on an American robin, Turdus migratorius, and 2 on a chipping sparrow, Spizella passerina. This tick was not found on small mammals at Thunder Cape. Twenty-six larvae and a nymph of the rabbit tick, Haemaphysalis leporispalustris (Packard) were found on 1 American robin, 2 Swainson's thrushes, Catharus ustulatus, 1 white-throated sparrow, Zonotrichia albicollis, 1 common yellowthroat, Geothlypis trichas, 1 blue jay, and 12 chipping sparrows. A nymph of H. chordeilis (Packard) occurred on 1 chipping sparrow. Results demonstrate that northward migrating birds transport larvae of I. scapularis to areas of Ontario where the tick does not appear to have become established in small mammal populations. Spring migrants may be more involved in the dispersal of I. scapularis larvae than previously thought. Cooler temperatures and shorter seasons experienced in the more northerly, continental parts of the established distribution of this tick may extend the life cycle, resulting in a predominance of larvae rather than nymphs being acquired by northward-bound birds in early spring. Consequently, the role of spring migrating birds in the northward spread of I. scapularis and of borreliosis should be reevaluated.

Animals↗
PubMed1994

Synthesis of a fluorescent steroid derivative with high affinities for the glucocorticoid and progesterone receptors.

The synthesis of RU 45196, an 11 beta-substituted 19-norsteroid of the estra-4,9-diene series, incorporating the nitrobenzoxadiazole (NBD) fluorophore, is reported. The highly fluorescent target compound displayed remarkable affinity for both the progesterone and glucocorticoid receptors. The present work demonstrates for the first time that it is indeed possible to design fluorescent steroid conjugates which maintain very high affinities for their cognate receptors and which are potentially useful for mechanistic and diagnostic purposes.

Affinity Labels↗
PubMed1992

Antibacterial activity of RU44790, a new N-tetrazolyl monocyclic beta-lactam.

RU44790 belongs to a new class of synthetic monocyclic beta-lactam antibiotics which feature a bioisosteric tetrazole moiety instead of the more classical acidic functions at the N-1 position of the beta-lactam ring. Its antibacterial activity was evaluated against some 900 strains and was compared with those of other recent beta-lactam derivatives, especially aztreonam. RU44790 is endowed with potent activity against gram-negative bacteria. At less than or equal to 0.6 micrograms/ml, RU44790 inhibited 90% of all strains of the family Enterobacteriaceae with the exception of Citrobacter spp. (MIC for 90% of strains tested, 1.2 micrograms/ml). The activity was similar to that of aztreonam against strains that are normally susceptible to expanded-spectrum cephalosporins. On the other hand, the new compound was 10 to 100 times more potent than aztreonam and most of the other antibiotics tested against enterobacteria that produce chromosome-encoded or plasmid-mediated extended-spectrum beta-lactamases. Pseudomonas aeruginosa isolates were equally susceptible to both monobactams. RU44790 was inactive against staphylococci and had only marginal activity against streptococci (MIC for 50% of strains tested, 2.5 micrograms/ml). RU44790 was highly resistant to hydrolysis by various beta-lactamases, particularly cephalosporinases such as P99. The latter enzyme was also inhibited by the compound. RU44790 showed a high affinity for penicillin-binding protein 3 of Escherichia coli. The results suggest that RU44790 has good potential in the treatment of infections caused by gram-negative microorganisms.

Anti-Bacterial Agents↗