Psoralen/UVA treatment and chromosomes

Summary Treatment of human lymphocytes in vitro with trimethylpsoralen or 8-methoxypsoralen and UVA irradiation (PUVA) induced chromosome damage, mainly constrictions and gaps, but also breaks and exchanges, and increased the frequency of sister chromatid exchange (SCE). The localization of the chromosome aberrations was nonrandom. The coincidence of many PUVA hits with mercaptoenthanol hits suggests that PUVA may have other targets in the cell than the DNA, perhaps the folding proteins of the chromosomes and the nuclear membrane/chromatin attachment organelles.Caffeine increased in a synergistic way the chromosome aberration yield if added after PUVA treatment, but there was no effect when caffeine was present before and during PUVA treatment. The SCE frequency was increased in the presence of caffeine.     

Revision der GattungLoxonia (Gesneriaceae)

Within the genusLoxonia Jack, currently regarded as monotypic, three species are recognized:L. hirsuta Jack (Sumatra, Mentawai-Islands, Java, Borneo, Anambas-Islands, Malay Peninsula),L. discolor Jack (Sumatra) andL. burttiana A. Weber, spec. nova (Borneo). [Key with English translation p. 203.] There is evidence thatL. discolor is the most primitive species within the genus, the two others being derived from it.

Teil V der Beiträge zur Morphologie und Systematik derKlugieae undLoxonieae (Gesneriaceae).     

Comparison of the in vivo clearance of des-AA and des-AABB rat fibrin monomers prepared by different methods

Solubilization of fibrin monomers (Fm's) is usually performed with dilute acetic acid, urea or sodium bromide. These solvents can affect the biological properties of Fm's. Therefore we describe a new method to keep Fm's in solution, under milder conditions i.e. by generating them in Dcate solutions and avoiding non-physiological conditions. The in vivo behaviour of iodinated rat Fm's injected in rats and prepared by this new method was compared with that of Fm's dissolved in acetic acid, urea or sodium bromide.Fm's prepared in Dcate solutions accumulate rapidly, within 10 minutes after injection, in all organs tested, predominantly in kidney, liver and lung, probably by interaction with endothelial cells. The blood radioactivity remains nearly constant during the first 90 minutes and decreases thereafter exponentially. Fm's dissolved in sodium bromide behave similarly. However, Fm's dissolved in acetic acid or urea behave differently and do not accumulate in organs. This suggests that Fm's loose their capability to accumulate in organs and probably to interact with endothelial cells when they have been dissolved in acetic acid or urea.The slow exponential clearance phase does not differ significantly between the various Fm's and their $\text{T}\text{1}\text{2'S}$ are estimated to lie between 5 and 7 hours.     

Foliicole Flechten aus der Kolchis (West-Transkaukasien,UdSSR)

This paper deals with 19 species of foliicolous lichens collected in the summer months of 1977 to 1980 during several excursions to the vicinity of the spas Sochi, Gagra and Sukhumi on the east shores of the Black Sea (part of the Colchis). Some new taxa and one new combination are proposed:Raciborskiella minor Vězda (sp. n.),Porina colchica Vězda (sp. n.),Gyalectidium caucasicum (Elenk. etWoronich.)Vězda (comb. n.),G. colchicum Vězda (sp. n.),Bacidia vasakii Vězda (sp. n.). Taxonomical, ecological and plant geographical notes to all species are given.     

Ecomorphological survey of the leaf characteristics in selected Central European plant communities

Starting from the significance of the leaf surface for synmorphology, synecology, herbivory, decomposition and other use values, the leaf shape and size, consistency and seasonality have been surveyed in some forest and nonforested Central European communities. In both the individual species and the plant communities, the leaf size and shape are linearly correlated with mineral nutrient supply and, to some extent, also by soil moisture, both factors having been evaluated according to the importance value for each indicator species. Leaf consistency and periodicity tend to coincidewith the moisture gradient. Noteworthy is the smoothing influence of the forest canopy on the representation of various leaf categories in comparison with nonforested communities. No correlation was found between the light factor and the representation of leaf graminoid types.     

Depolarization-induced release of [3H]histamine by high potassium concentrations,electrical stimulation and veratrine from rat brain slices after incubation with the radiolabelled amine

Brain slices obtained from neocortex, hypothalamus or hippocampus were incubated with [³H]histamine and subsequently superfused and exposed to different depolarizing stimuli, viz. high K⁺-concentrations, electrical field stimulation and veratrine. K⁺-induced release of tritium was completely calcium-dependent and its magnitude depended on the K⁺-concentration, with maximal release being reached at 56 mM K⁺. Electrically-evoked release of tritium increased with increasing frequencies and reached its maximum at about 20 Hz. The electrically-evoked release appeared to be totally calcium-dependent and it was strongly inhibited by tetrodotoxin. Veratrine (5–100 μM) also induced a release of tritium; maximal release was obtained at 100 μM veratrine. Veratrine-induced release was partially calcium-dependent and was strongly reduced by tetrodotoxin.Taken together the data indicate that the depolarization-induced release of tritium from brain slices pre-labelled with [³H]histamine, represents [³H]histamine release from neurons and not from either mast cells or glial cells. It remains to be established whether these neurons are specifically histaminergic.     

Toxicological evaluation of agromet (Metalaxyl) preparation.

A complex toxicological study was carried out in relation to the hygienic standardization of the fungicide preparation Ridomil, whose forthcoming production in this country will be under the name Metalaxyl. The study was performed on sexually mature white rats of both sexes, at oral, dermal and inhalation exposure, acute, subacute and chronic experiments, according to the Bulgarian State Standard. Besides the routine toxicological studies were carried also studies for establishing the long-term effects of the preparation (gonadotropic, embryotoxic and teratogenic, cardiovascular). The results from the study permitted the Agromet preparation to be put in III class--moderately toxic according to limiting index LD50 oral. On the basis of data from the authors study on the general toxicity and long-term effects of Metalaxyl a temporary MAC 4 mg/m3 was proposed.     

Evidence for an ancestral core structure in nucleotide-binding proteins with the type A motif

Many proteins that bind purine nucleotide triphosphates have a type A sequence motif. Only two classes of structures for such proteins are so far available from X-ray crystallography. We examined the tertiary structures of representatives of the two classes, porcine cytoplasmic adenylate kinase and Escherichia coli translational elongation factor Tu. Comparison of the two proteins suggests that the A motif may be just one part of a larger common core structure consisting of four parallel strands of beta-sheet sandwiched between four alpha-helices. This compact core structure comprises over one half of each protein. We speculate that A motif proteins have diverged from a common ancestor having this core structure.     

Morphologic, phenotypic, and cytotoxic analyses of C57BL/6 murine non-parenchymal liver cells: new evidence associating murine liver large granular lymphocytes with monocyte precursors and implications for tumor immunotherapy.

Non-parenchymal liver cells (NPCs) have been implicated in murine host resistance to hepatic metastases. We have examined the relative cell number, morphology, phenotype, and cytotoxic potential of Percoll fractionated C57BL/6 murine liver NPCs. Low density (Percoll fractions 2 and 3) cells showed a large granular lymphocyte morphology and made up 76% of all NPCs recoverable, while high density (fractions 5 and 6) showed a small lymphocyte morphology and made up 10% of all NPCs. Low density cells demonstrated the following phenotype: 14% of the cells demonstrated the Thy 1.2 marker; 12%, the Lyt-2 marker; 67%, the L3T4 marker; 74%, the asialo GM1 marker; 30%, the 49H.8 marker; and 65%, the F4/80 marker. The high density cells expressed the same markers on 71%, 21%, 33%, 68%, 37%, and 19% of their cell surface, respectively. There were no differences phenotypically between high density NPCs and splenocytes except for the F4/80 expression (fractions 5 and 6 NPCs, F4/80 expression 19%, fresh splenocytes 60%). Dual color analysis of L3T4+ NPCs documented that fractions 2 and 3 cells also expressed the F4/80 marker on 85% of their cell surface and the Thy 1.2 marker on 11% of their cell surface. The high density fractions 5 and 6 L3T4+ cells expressed the F4/80 marker on 16% of their cell surface, and the Thy 1.2 marker on 89% of their cell surface. Cytotoxicity against YAC-1 [a natural killer (NK) sensitive target], MCA-102 (a NK resistant target), and WEHI-164 (a natural cytotoxicity target) were similar for fractions 2 and 3, and 5 and 6 cells. Based upon the expression of the F4/80 marker on L3T4+ cells that are Thy 1.2 negative and appear to be similar to LGLs morphologically (fractions 2 and 3 NPCs), we propose that these cells are monocyte precursors while fractions 5 and 6 cells are small lymphocytes. These findings with liver LGLs support the need for the evaluation of monocyte directed biological response modifiers in therapeutic models of murine hepatic metastases.     

Mitotic activity in the blastema and stump tissues of regenerating hind limbs of Xenopus laevis larvae after amputation at ankle level. An autoradiographic study

Mitotic activity, as indicated by DNA synthesis, was studied by autoradiographic analysis along the proximodistal axis of regenerating limbs in the early and later larval stages 53 and 57 of Xenopus laevis. Wound-healing, dedifferentiation, blastema formation and growth phases were studied. Most of the various stump tissues, as well as the cell mass of the regeneration blastema, were involved. The study showed an increase in DNA synthesis in the stump tissues during their dedifferentiation as well as during blastema formation. The increase was confined mainly to the distal portion (close to the amputation level), so that a proximodistal gradient was discernible. This could be regarded as valid evidence of contribution of the severed stump tissues to the blastema cells. The mesenchymal blastema cells formed after amputation at stage 53 displayed higher mitotic activity than the fibrocytoid blastema cells formed at stage 57. Although the latter were more differentiated than the former, they still showed DNA replication and mitotic division.