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.     

Transforming growth factor-β inhibition of interleukin-1 activity involves down-regulation of interleukin-1 receptors on chondrocytes

Interleukin-1 (IL-1) plays an important role in cartilage destruction associated with inflammatory and degenerative arthritis because of its ability to induce matrix degrading enzymes. Previously, we have shown that the IL-1-induced chondrocyte protease activity was inhibited by transforming growth factor-β (TGF-β). In this paper, we show that TGF-β inhibits the IL-1-induced synthesis of collagenase and stromelysin by reducing the steady-state mRNA levels in rabbit articular chondrocytes. We further demonstrate that TGF-β-treated chondrocytes show reduced ¹²⁵I-IL-1 binding that returns to a normal level when TGF-β is removed from the culture medium. The inhibitory effect of TGF-β is observed for both naturally occurring as well as fibroblast growth factor (FGF)-inducible binding sites (receptors). Scatchard analysis of receptor—ligand interactions demonstrate that the reduced binding is due to a reduction in the number of receptors for IL-1 and is not due to changes in affinity. Affinity cross-linking studies suggest that control chondrocytes contain two major cross-linked bands of M_r =116 and 80 kDa and a minor band of M_r =100 kDa. FGF-treated cells show enhanced levels of all the bands, plus an additional 200-kDa band. TGF-β treatment of chondrocytes results in the reduction of all of these bands in both control as well as FGF-induced cells. These observations suggest that the ability of TGF-β to down-regulate the IL-1 receptor may be a mechanism by which it exerts its effects in antagonizing the IL-1 activity on chondrocytes.     

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.     

Detection of methandienone (methandrostenolone) and metabolites in horse urine by gas chromatography—mass spectrometry

The metabolic transformation of methandienone (I) in the horse was investigated. After administration of a commercial drug preparation to a female horse (0.5 mg/kg), urine samples were collected up to 96 h and processed without enzymic hydrolysis. Extraction was performed by a series of solid—liquid and liquid—liquid extractions, thus avoiding laborious purification techniques. For analysis by gas chromatography—mass spectrometry, the extracts were trimethylsilylated. Besides the parent compound I and its C-17 epimer II, three monohydroxylated metabolites were identified: 6β-hydroxymethandienone (III), its C-17 epimer (IV) and 16β-hydroxy-methandienone (V). In addition, three isomers of 6β,16-dihydroxymethandienone (VIa–c) were discovered. Apparently, reduction of the δ⁴ double bond of 16β-hyroxymethandienone (V) in the horse yields 16β,17β-dihydroxy-17α-methyl-5β-androst-1-en-3-one (VII). Reduction of the isomers VIa–c results in the corresponding 6β,16,17-trihydroxy-17-methyl-5β-androst-1-en-3-ones (VIIIa–c). The data presented here suggest that screening for the isomers of VI and VIII, applying the selected-ion monitoring technique, will be the most successful way of proving methandienone administration to a horse.     

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.     

Occurrence of Cladocera (Crustacea) in subterranean waters in Yugoslavia

Contrary to some localities in France and Spain, Cladocera occur in hypogean waters in Yugoslavia very sporadically. Beside the stygobitic species, Alona hercegovinae from caves and Alona smirnovi from interstitial waters, particularly some other Chydoridae seem to be suited for hypogean life. Chydorus sphaericus, reputed as one of the most euryoecious cladocerans, occurs also the deepest in interstitial waters as well as in caves. Other species, found in hypogean waters are Simocephalus vetulus, Ilyocryptus sordidus, Eurycercus lamellatus, Chydorus ovalis, Leydigia leydigi, Acroperus harpae and Biapertura affnis.     

Porewater chemistry of inorganic nitrogen compounds in the eastern Skagerrak (NE North Sea)

Porosity, Eh and interstitital nitrogen compounds profiles are given for four locations in the eastern Skagerrak. Sediments down to 30 cm depth, i.e. postindustrial in age, were analysed. The results together with a detailed age determination (²¹⁰Pb) suggest a high degree of both lateral and vertical variability as a result of local bottom topography and currents as well as event-controlled sedimentation processes.