Insulin antagonizes the phagocytosis stimulating action of histamine in Tetrahymena

Histamine increased specifically the phagocytic activity of the unicellular Tetrahymena, whereas insulin had no influence on it. Insulin antagonized the phagocytosis stimulating action of histamine after simultaneous exposure and after preexposure two days earlier as well, although in the latter case to a lesser degree. Double exposure to a combination of histamine + insulin didn't influence the phagocytic activity at all, demonstrating the histamine antagonizing effect of insulin in this model.     

Synthesis and biological evolution of hydrazones derived from 4-(trifluoromethyl)benzohydrazide

Reflecting the known biological activity of isoniazid-based hydrazones, seventeen hydrazones of 4-(trifluoromethyl)benzohydrazide as their bioisosters were synthesized from various benzaldehydes and aliphatic ketones. The compounds were screened for their in vitro activity against Mycobacterium tuberculosis, nontuberculous mycobacteria (M. avium, M. kansasii), bacterial and fungal strains. The most antimicrobial potent derivatives were also investigated for their cytostatic and cytotoxic properties against three cell lines. Camphor-based molecule, 4-(trifluoromethyl)-N′-(1,7,7-trimethylbicyclo[2.2.1]heptan-2-ylidene)benzohydrazide, exhibited the highest and selective inhibition of M. tuberculosis with the minimum inhibitory concentration (MIC) of 4?µM, while N′-(4-chlorobenzylidene)-4-(trifluoromethyl)benzohydrazide was found to be superior against M. kansasii (MIC?=?16?µM). N′-(5-Chloro-2-hydroxybenzylidene)-4-(trifluoromethyl)benzohydrazide showed the lowest MIC values for gram-positive bacteria including methicillin-resistant Staphylococcus aureus as well as against two fungal strains of Candida glabrata and Trichophyton mentagrophytes within the range of ≤0.49–3.9?µM. The convenient substitution of benzylidene moiety at the position 4 or the presence of 5-chloro-2-hydroxybenzylidene scaffold concomitantly with a sufficient lipophilicity are essential for the noticeable antimicrobial activity. This 5-chlorosalicylidene derivative avoided any cytotoxicity on two mammalian cell cultures (HepG2, BMMΦ) up to the concentration of 100?µM, but it affected the growth of MonoMac6 cells.     

Cold Response of Dedifferentiated Barley Cells at the Gene Expression, Hormone Composition, and Freezing Tolerance Levels: Studies on Callus Cultures

In this study, data is presented how dark-grown, embryogenic barley callus cells respond to cold without any light-dependent, chloroplast-related mechanism, independently of the systemic signals. The expression of HvCBF9, HvCBF14, and HvCOR14b genes, members of one of the most important cold-inducible regulatory system, was measured by real-time PCR. Characteristic of the cold response was similar in the crowns of seedlings and in dark-grown callus cultures, however, gene expression levels were lower in calli. Endogenous concentration of auxins, abscisic acid, and salicylic acid did not change, but phaseic acid and neophaseic acid showed robust accumulation after cold acclimation. Freezing tolerance of the cultures was also higher after 7 days of cold-hardening. The results suggest the presence of a basal, light-independent, cold-responsive activation of the CBF–COR14b pathway in barley cultures. The effects of Dicamba, the exogenous auxin analog used for maintaining tissue cultures were also studied. Dicamba seems to be a general enhancer of the gene expression and physiological responses to cold stress, but has no specific effect on the activation. Our data along with previous findings show that this system might be a suitable model for studying certain basic cellular mechanisms involved in the cold acclimation process in cereals.     

Regulation of angiogenesis by hypoxia: the role of microRNA

Understanding the cellular pathways that regulate angiogenesis during hypoxia is a necessary aspect in the development of novel treatments for cardiovascular disorders. Although the pathways of angiogenesis have been extensively studied, there is limited information on the role of miRNAs in this process. miRNAs or their antagomirs could be used in future therapeutic approaches to regulate hypoxia-induced angiogenesis, so it is critical to understand their role in governing angiogenesis during hypoxic conditions. Although hypoxia and ischemia change the expression profile of many miRNAs, a functional role for a limited number of so-called hypoxamiRs has been demonstrated in angiogenesis. Here, we discuss the best examples that illustrate the role of hypoxamiRs in angiogenesis.     

Characterization of calcium signals in human embryonic stem cells and in their differentiated offspring by a stably integrated calcium indicator protein

Intracellular calcium signaling pathways play a major role in cellular responses such as proliferation, differentiation and apoptosis. Human embryonic stem cells (hESC) provide new possibilities to explore the development and differentiation of various cell types of the human body. Intracellular calcium responses to various ligands and the calcium signaling pathways, however, have not been thoroughly studied in embryonic stem cells and in their differentiated progenies. In our previous work we demonstrated that the use of the fluorescent calcium indicator Fluo-4 with confocal microscopy allows sensitive and reliable measurements of calcium modulation in human embryonic stem cells and stem-cell derived cardiomyocytes. Here we developed a human embryonic stem cell line stably expressing a genetically encoded Ca^2 + indicator (GCaMP2) using a transposon-based gene delivery system. We found that the differentiation properties were fully preserved in the GCaMP2-expressing hESC lines and Ca imaging could be performed without the need of toxic dye-loading of the cells. In undifferentiated hES cells the calcium signals induced by various ligands, ATP, LPA, trypsin or angiotensin II were comparable to those in Fluo-4 loaded cells. In accordance with previous findings, no calcium signal was evoked by thrombin, histamine or GABA. Cardiomyocyte colonies differentiated from hES-GCaMP2 cells could be recognized by spontaneous contractions and Ca^2 + oscillations. GCaMP2-expressing neural cells were identified based on their morphological and immuno-staining properties and Ca signals were characterized on those cells. Characteristics of both the spontaneous and ligand-induced Ca^2 + signals, as well as their pharmacological modification could be successfully examined in these model cells by fluorescence imaging.     

Complexes of aluminium with peptide ligands: A fourier transform IR spectroscopic study

Aluminium has been recognized to be a neurotoxic agent and a risk factor in Alzheimer's disease and other neuronal dysfunctions. CD spectroscopic studies on two synthetic fragments of the human neurofilament protein midsized subunit (NF-M), and their alanine-for-serine-substituled and /or serine-phosphorylated derivatives showed the formation of stable, citric acid resistant complexes of Al³⁺with peptide ligands [M. Hollósi, Z.M. Shen, A. Perczel, and G.D. Fasman (1994) Proc. Natl. Acad. Sci. USA, vol. 9 , pp.4902-4906]. In the case of Ser-phosphorylated fragments, aβ-sheet inducing effect of Ca²⁺ and Al³⁺ ions was observed. However, the serine-containing parent peptides, NF-M 13 (KSPVPKSPVEEKG) and NF-M 17 (EEKGKSPVPKSPVEEKG), failed to show CD spectral changes reflecting β-sheet formation upon addition of Al³⁺ ions. On the basis of the amide I region of the Fourier transform ir spectra, in triftuoroethanol, the peptide backbone of NF-M17 and NF-M17 (A⁶A¹¹) shows marked changes in the presence ofAl³⁺. The most significant spectral differences are seen in the car-boxyl region (> 1700 cm^?l). The high-frequency component bands above 1760 cm^?1 in both spectra belong to the C? O of undissociated CF₃COOH. Another strong band at 1710 cm^?1 which appears only in the spectrum of NF-Ml 7 (A⁶A¹¹)(NF-M17 with Ser⁶ andSer¹¹ replaced by Ala) can be assigned to the side chain or C-terminal COOH groups. The differential proton-ation state of the carboxyl groups in the two peptides suggests the format ion ofAl³⁺ complexes of different structure and stability. The Al³⁺ complex ofNF-Ml 7 (A⁶A¹¹) is likely less stable, or one or more of the carboxylates are not coordinated to the Al³⁺ and thus can serve as a base to bind the liberated protons. In NF-M17 the OH groups of serines facilitate the formation of type [Al-pep(H_-1)] complexes with the involvement of all carboxylategroups in the molecule. The relevance of intramolecular and intermolecular Al³⁺ binding to the controversial biological role of aluminium is also discussed. © 1995 John Wiley & Sons, Inc.     

Polymorphism and inheritance of serum esterases and β-globulins in the paradise fish (Macropodus opercularis; Anabantidae)

Electrophoretic variants of serum esterases and β-globulins in two subspecies of paradise fish ( Macropodus opercularis ) were studied. Four esterase loci ( Est-1, Est-2, Est-3 and Est-4 ), a single transferin ( Tf ) and another major β-globulin locus ( Bg ) were identified by segregational analysis. Est-3 seems to be a monomorphic. locus. Three alleles of Est-1 , two of Est-2 , two of Est-4 , four of Tf and two alleles of Bg were found in the laboratory population. None of these loci were closely linked. Electrophoretic patterns of F₁ hybrids confirmed the monomeric structures of each of the studied proteins. Allelic segregation at the Tf and Bg loci was normal in F₂ and backcross populations. In crosses of the two Macropodus subspecies there were deviations from Mendelian ratios because of missing recombinant esterase phenotypes. Each of these would have been homozygous Est-2^f/f . We suppose that Est-2^f/f causes lethality in the early phase of development, except in the Est-1^c/c, Est-2^f/f combination characteristic of the parental subspecies M.o. concolor .     

Scanning electron microscopic study of human gallbladder mucosa in cholelithiasis

The mucosa of 17 gallbladders removed because of cholelithiasis was examined by means of transmission and scanning electron microscopy. Scanning electron micrographs revealed a mulberry-like organization of the normal human gallbladder mucosa. In acute inflammation, circumscribed ulcers were often seen; along their margins the epithelial cells were swollen and isolated from the surrounding cells. In chronic cholecystitis there was an extensive lack of epithelium on the irregularly oriented folds of the mucosa and the characteristic mulberry-like organization was preserved only in islets.     

Rapid clonal multiplication of Digitalis lanata in tissue culture

Shoot cultures of Digitalis lanata have been established by inoculating the shoot tip of seedlings germinated in aseptic culture, or of field-grown plants, onto Linsmaier and Skoog's RM medium supplemented with 1 mg 6-benzylaminopurine and 0.1 mg indolacetic acid 1^–1. On this medium formation of up to 30 new axillary shoots could be induced. Shoots could be grown into functional plants after root induction on a medium containing reduced amounts (one-fifth of normal) of nitrogen and indolebutyric acid (0.5 mg 1^–1).