Impaired local natural killer cell activity in human colorectal carcinomas

Summary The present study was undertaken to study natural killer (NK) cell activity in patients with colorectal cancer at peripheral and local levels. Mononuclear cells were isolated from uninvolved colorectal mucosa, tumor tissue and peripheral blood, and tested against the colon carcinoma cell line CaCo-2 and the erythroleukemia cell line K-562. Peripheral blood NK cell activity from the patients showed similar levels compared with healthy controls, whereas, mononuclear cells of tumor tissue were found to have a significantly decreased NK cell activity compared to the normal intestinal mucosa (P<0.01). No relation was found between the NK cell activity and the advancement of the disease according to the Duke's stage. Interferon- (IFN-) stimulated the NK cell activity of the mononuclear cells from blood, mucosa and tumor. However, the increase of NK cell activity after IFN- stimulation was lower in the tumor compared to the mucosa (P<0.02). The lectin, phytohaemagglutinin, increased the cytotoxicity of mononuclear cells from blood, mucosa and tumor to a similar level. These results suggest that patients with colorectal tumors exhibit a normal NK cell activity in peripheral blood and intestinal mucosa; however, a diminished NK cell activity exists at the tumor level. Although mononuclear cells isolated from the tumor have a normal response to lectin stimulation they show hyporesponsiveness to IFN- stimulation with regard to their NK cell activity.     

Class I major histocompatibility complex cDNA clones from sheep thymus: alternative splicing could make a long cytoplasmic tail

To investigate the class I major histocompatibility complex (MHC) genes expressed in the young sheep thymus, a cDNA library was screened with a human HLA-B7 cDNA probe under conditions of relaxed stringency. Thirteen clones were isolated and found by partial sequences to fall into five classes, requiring the expression of at least three loci. One sequence was found six times, almost half of the total, and may thus represent the major message expressed in the young sheep thymus. One of the clones was found to have failed to excise the intron between cytoplasmic exons 7 and 8, leading to the predicted synthesis of a cytoplasmic domain 23 amino acids longer than the other sheep sequences, and 15 amino acids longer than any cytoplasmic domain previously described. The sequences of all the clones were found to be most similar to bovine, and least similar to mouse class I MHC sequences.The nucleotide sequence data reported in this paper have been sunmitted to the GenBank nucleotide sequence database and have been assigned the accession numbers M 34672-6.     

Polymorphic arylamine N-acetyltransferase encoding gene (NAT2) from homozygous rapid and slow acetylator congenic Syrian hamsters

The nucleotide (nt) and deduced amino acid (aa) sequences were determined for polymorphic arylamine N-acetyl-transferase (NAT2) and its gene, NAT2, from homozygous rapid and slow acetylator congenic Syrian hamsters. The slow acetylator (NAT2^s) allele contained three point mutations which differed from the rapid acetylator allele (NAT2^r); two mutations were silent, and the third mutation resulted in a premature stop codon. The NAT2^r allele contained a truncated open reading frame of 726 nt encoding a 242-aa protein, which is 48-aa shorter than NAT2^r.     

Sequence analysis of sheep T-cell receptor β chains

The nucleotide sequences reported in this paper have been submitted to the GenBank database and have been assigned the accession numbers M94181-M94183.     

Role of FGFs in skeletal muscle and limb development

Fibroblast growth factors (FGFs) are a family of nine proteins that bind to three distinct types of cell surface molecules: (i) FGF receptor tyrosine kinases (FGFR-1 through FGFR-4); (ii) a cysteine-rich FGF receptor (CFR); and (iii) heparan sulfate proteoglycans (HSPGs). Signaling by FGFs requires participation of at least two of these receptors: the FGFRs and HSPGs form a signaling complex. The length and sulfation pattern of the heparan sulfate chain determines both the activity of the signaling complex and, in part, the ligand specificity for FGFR-1. Thus, the heparan sulfate proteoglycans are likely to play an essential role in signaling. We have recently identified a role for FGF in limb bud development in vivo. In the chick limb bud, ectopic expression of the 18 kDa form of FGF-2 or FGF-2 fused to an artificial signal peptide at its amino terminus causes skeletal duplications. These data, and the observations that FGF-2 is localized to the subjacent mesoderm and the apical ectodermal ridge in the early developing limb, suggest that FGF-2 plays an important role in limb outgrowth. We propose that FGF-2 is an apical ectodermal ridgederived factor that participates in limb outgrowth and patterning. © 1994 Wiley-Liss, Inc.     

History of diatom research in The Netherlands and Flanders

The history of diatom research in The Netherlands and Flanders is summarized in this report. A. van Leeuwenhoek observed diatoms as early as 1702. The first inventories were made in The Netherlands by R. B. van den Bosch (1846) and in Flanders by J.-J. Kickx (1867). Diatoms were already used in geological research in the second half of the nineteenth century. The Synopsis by H. van Heurck (1880–1885) enabled many twentieth century workers to do applied research for geological and ecological purposes.     

Plasma esterase activities in rats fed magnesium-deficient diets

In a study with rats it was determined whether dietary magnesium concentration affects plasma esterase activities. The feeding of a diet with 0.01% (w/w) instead of 0.04% magnesium reduced plasma magnesium concentration by 50%. Plasma total esterase, arylesterase and butyrylcholinesterase activities were significantly decreased in the magnesium-deficient rats. In rats fed a diet containing 0.02% magnesium, plasma magnesium concentration was lowered by 30%, and group mean plasma total esterase activity was decreased, but not the activities of arylesterase and butyrylcholinesterase.