NALL-1, an acute lymphoblastic leukemia cell line with peroxidase activity

Summary All cells examined from the non-B, non-T acute lymphoblastic leukemia cell line, NALL-1, stained positive both for terminal deoxynucleotidyl transferase and for common ALL antigen. In addition, peroxidase activity was detected by light microscopy in 55 to 75% of cells and peroxidase-positive granules were detected ultrastructurally in >80% of cells. Peroxidase activity in NALL-1 may result from derepression of peroxidase genes or clonal proliferation of a biphenotypic precursor cell.     

Multitargeted drugs discovery: balancing anti-amyloid and anticholinesterase capacity in a single chemical entity

Memoquin (1) is a lead compound multitargeted against Alzheimer’s disease (AD). It is an AChE inhibitor, free-radical scavenger, and inhibitor of amyloid-β (Aβ) aggregation. A new series of 1 derivatives was designed and synthesized by linking its 2,5-diamino-benzoquinone core with motifs that are present in the structure of known amyloid binding agents like curcumin, the benzofuran derivative SKF64346, or the benzothiazole bearing compounds KHG21834 and BTA-1. The weaker AChE inhibitory potencies and the concomitant nearly equipotent anti-amyloid activities of the new compounds with respect to 1 resulted in a more balanced biological profile against both targets. Selected compounds turned out to be effective Aβ aggregation inhibitors in a cell-based assay. By properly combining two or more distinct pharmacological properties in a molecule, we can achieve greater effectiveness compared to single-targeted drugs for investigating AD.     

Monocyte nonspecific esterase. Enzymologic characterization of a neutral serine esterase associated with myeloid cells

Monocytes contain a characteristic, prominent set of membrane-bound nonspecific esterases with a slightly acid isoelectric point. These esterases are also detected at modest levels in some granulocyte preparations. They are not apparent in lymphocytes. Among 18 fresh myeloid leukemias and myeloid leukemia cell lines, those of subtypes M4 (myelomonocytic) and M5 (monocytic) were strongly positive; some of subtypes M1-M3 (granulocytic) were moderately positive. The esterases were not detected among 32 fresh lymphoid leukemias and lymphoid leukemia and lymphoblast cell lines. The membrane-bound monocyte esterases, solubilized by treatment of monocyte preparations with nonionic detergent, were resolved by ion-exchange chromatography. The monocyte species account for 80-95% of the total nonspecific esterase activity of monocytes. The resolved enzymes behave as neutral serine carboxyl esterases and are highly sensitive to inhibition by diisopropylfluorophosphate (DFP) and also by sodium fluoride. Similar analysis of a lymphocyte preparation yielded no detectable monocyte esterases, but yielded numerous other forms which were generally resistant to inhibition by DFP and NaF. These nonspecific esterases are also present at background levels in monocytes. The resolution and characterization of the membrane-bound serine esterases from monocytes demonstrates the basis for the well-known cytochemistry of monocytes. The results are also crucial to the development of an immunologic surface marker test for myeloid cells and the study of monocyte membrane physiology.     

Changing characteristics of the milk-ejection reflex during pregnancy, lactation and after weaning in the rat

The pattern of reflex milk ejection during suckling was investigated in anaesthetized Wistar rats at various stages of pregnancy, lactation and after weaning. Milk-ejection responses were measured using intramammary pressure recordings, and the amount of oxytocin released was estimated from log dose-response lines compiled from the mammary responses to exogenous oxytocin. The number of rats showing intramammary pressure responses to oxytocin increased on Day 22 of pregnancy (the day of parturition) and decreased at 8 days after weaning. The dose-response lines from pregnant animals were shallow, but steepened and shifted to the left during lactation and after weaning. Reflex milk-ejection responses during suckling were detectable in primigravid animals, indicating that birth of the litter and previous suckling experience are unnecessary for the immediate functioning of the reflex. Reflex milk-ejection responses improved during early lactation (such that the frequency and the amount of oxytocin released at each response were maximal at Day 10 of lactation), and subsequently declined in late lactation. Although the frequency of responses in animals 2 and 4 days after weaning was similar to that in late lactating animals, the amount of oxytocin released at each response had risen again to mid-lactation values. In animals undergoing a second pregnancy and lactation the pattern of change in the milk-ejection responses was similar to that of primiparous animals.     

NALL-1, an acute lymphoblastic leukemia cell line with peroxidase activity

All cells examined from the non-B, non-T acute lymphoblastic leukemia cell line, NALL-1, stained positive both for terminal deoxynucleotidyl transferase and for common ALL antigen. In addition, peroxidase activity was detected by light microscopy in 55 to 75% of cells and peroxidase-positive granules were detected ultrastructurally in greater than 80% of cells. Peroxidase activity in NALL-1 may result from derepression of peroxidase genes or clonal proliferation of a biphenotypic precursor cell.     

Conformational study of bovine lactoferricin in membrane-micking conditions by molecular dynamics simulation and circular dichroism

Lactoferricins are potent antimicrobial peptides released by pepsin cleavage of Lactoferrins. Bovine Lactoferricin (LfcinB) has higher activity than the intact bovine Lactoferrin, and is the most active among the other Lactoferricins of human, murine and caprine origin. In the intact protein the fragment corresponding to LfcinB is in an helical conformation, while in water LfcinB adopts an amphipathic β-hairpin structure. However, whether any of these structural motifs is the antibacterial active conformation, i.e., the one interacting with bacterial membrane components, remains to be seen. Here we present Circular Dichroism (CD) spectra and Molecular Dynamics (MD) simulations indicating that in membrane-mimicking solvents the LfcinB adopts an amphipathic β-hairpin structure similar to that observed in water, but differing in the dynamic behavior of the side-chains of the two tryptophan residues. In the membrane-mimicking solvent these side-chains show a high propensity to point towards the hydrophobic environment, rather than being in the hydrophobic core as seen in water, while the backbone preserves the hairpin conformation as found in water. These results suggest that the tryptophans might act as anchors pulling the stable, solvent-invariant hairpin structure into the membrane.     

Proteins pattern alteration in AZT-treated K562 cells detected by two-dimensional gel electrophoresis and peptide mass fingerprinting

In this study we report the effect of AZT on the whole protein expression profile both in the control and the AZT-treated K562 cells, evidenced by two-dimensional gel electrophoresis and peptide mass fingerprinting analysis. Two-dimensional gels computer digital image analysis showed two spots that appeared up-regulated in AZT-treated cells and one spot present only in the drug exposed samples. Upon extraction and analysis by peptide mass fingerprinting, the first two spots were identified as PDI-A3 and stathmin, while the third one was proved to be NDPK-A. Conversely, two protein spots were present only in the untreated K562 cells, and were identified as SOD1 and HSP-60, respectively.     

First synthetic probe for the detection and quantification of a protein with a potential alpha,(2-->8)sialyltransferase activity

There is considerable interest in monitoring alpha,(2-->8)sialyltransferase (ST8) levels; however, there are few specific and sensitive methods to directly detect and quantitate the protein. This paper reports the development of a synthetic probe composed of oxidized colominic acid coupled to biotinyl-L-lysine hydrazide to detect and quantify ST8 with putative "initiase" activity and its use in three solid-phase applications. The detection limit observed for ST8 purified from K562 cells was approximately 2 pg by dot-blot analysis. In Western blots the probe bound and specifically recognized a protein band corresponding to ST8. In ELISA a linear dose response was obtained for pure protein in the range of 50-200 pg. Analysis of 3'-azido-3'deoxythymidine-treated cells by all three methods showed a reduction in ST8 compared to control cells; treated cells had 73% of control levels by ELISA. This probe will be useful for studies on the expression ST8 and its role in glycoconjugate biosynthesis.     

Behaviour of the Phenolic Compounds on Capsicum annuum Leaves Infected with Phytophthora capsici

In Capsicum annuum leaves, some phenolic compounds, such as chlorogenic acid and various apigenin or luteolin glycosides, can be separated by HPLC technique. During infection with Phytophthora capsici (the agent of pepper mildew), the concentrations of these compounds decreased. A fungal glucosidasic activity may be implicated, producing apigenin aglycon in the necrotic areas. Some of the phenolic compounds were only present in intercellular spaces, where their concentration increasedduring fungal infection, mostly in the resistant pepper cultivar. The involvement of phenolics in C. annuum resistance is discussed in relation to oxidative metabolism.