The synthesis and biochemical evaluation of new A1 selective adenosine receptor agonists containing 6-hydrazinopurine moieties

The synthesis and SAR of a series of novel derivatives of N-aminoadenosine is described, along with their in vitro effects in biochemical assays. The rat brain A₁ adenosine receptor binding of these compounds is very dependent upon the purine 2-substituent. The novel agonist, 2-chloro-N-[4-(phenylthio)-1-piperidinyl]adenosine, exhibits a L_i value for A₁ receptor binding of <1 nM.     

Expression of {beta}-galactoside {alpha}2,6-sialyltransferase does not alter the susceptibility of human colon cancer cells to NK-mediated cell lysis

The extent of processing of N-linked oligosaccharides and thesialylation of the target cell membranes has been positivelycorrelated with resistance to lysis mediated by NK cells, buta conclusive evidence has never been reached. Colon cancer tissuesexpress an increased activity of ß-ga-lactoside     

Differential uptake of liposomes varying in size and lipid composition by parenchymal and kupffer cells of mouse liver

Using liposomes differing in size and lipid composition, we have studied the uptake characteristics of the liver parenchymal and Kupffer cells. Desferal labeled with iron-59 was chosen as a radiomarker for the liposomal content, because Desferal in its free form does not cross cellular membranes. At various time intervals after an intravenous injection of liposomes into mice, the liver was perfused with collagenase, and the cells were separated in a Percoll gradient. It was found that large multilamellar liposomes (diameter of about 0.5 μm) were mainly taken up by the Kupffer cells. For these large liposomes, the rate of uptake by Kupffer cells was rapid, with maximum uptake at around 2 hours after liposome injection. Unexpectedly, small unilamellar liposomes (diameter of about 0.08 μm) were less effectively taken up by Kupffer cells, and the rate of uptake was slow, with a maximum uptake at about 10 hours after liposome injection. In contrast, parenchymal cells were more effective in taking up small liposomes and the uptake of large liposomes was negligible. In addition, liposomes made with a galactolipid as part of the lipid constituents appeared to have higher affinity to parenchymal cells than liposomes made without the galactolipid. These findings should be of importance in designing suitable liposomes for drug targeting.     

Auer-rod positive myelocytic leukemia cells in diffusion chambers: differentiation along the eosinophilic pathway

Auer-rod positive acute myelocytic leukemia (AML) blasts from a 33-year-old patient were cultured in diffusion chambers (DC) in order to test their differentiation potential. The cells were labeled with anti-human granulocyte anti-serum known to be negative for eosinophils, and evaluated using the unlabeled peroxidase-antiperoxidase (PAP) method. Parallel to a decline in the number of leukemic blasts there was an increase of up to 86% in the number of granulocytic cells belonging to the eosinophilic series. Auer-rod bodies were found in the eosinophilic cells even after 20 days in culture. Staining with anti-granulocyte antiserum failed to demonstrate positive cells at any time during DC culture. Based on the negative reaction with the anti-granulocytic antibodies already at an early stage of development evidence is provided for the existence of a progenitor cell exclusively committed to the eosinophilic pathway.     

A 17-bp insertion and a Phe215----Cys missense mutation in the dihydrolipoyl transacylase (E2) mRNA from a thiamine-responsive maple syrup urine disease patient WG-34.

We have amplified the cDNA for the transacylase (E2) subunit of the branched-chain alpha-ketoacid dehydrogenase (BCKAD) complex from a thiamine-responsive MSUD cell line (WG-34) by the polymerase chain reaction. Sequencing of the amplified WG-34 cDNA showed a 17-bp insertion (AAATACCTTGTTACCAG) apparently resulting from an aberrant splicing of the E2 gene, and a missense (T----G) mutation that changes Phe215 to Cys in the E2 subunit. The existence of these two mutations was confirmed by probing the amplified E2 cDNA or genomic DNA with allele-specific oligonucleotides. The above results support the thesis that the thiamine-responsive MSUD patient (WG-34) is a compound heterozygote at the E2 locus. The implication of the E2 mutations for the thiamine-responsiveness observed in this patient is discussed.     

Functional effects of thymopoietin32-36 (TP5) on cytotoxic lymphocyte precursor units (CLP-U). I. Enhancement of splenic CLP-U in vitro and in vivo after suboptimal antigenic stimulation

Cytotoxic lymphocyte precursor units (CLP-U) were enumerated in the spleens of C57BL/6 mice 3 days after i.p. injections of synthetic thymopoietin32-36 (TP5). One hundred to 1000 ng TP5/mouse potentiated splenic CLP-U, this effect being detectable only after suboptimal allogeneic sensitization (with 1.2 x 10(5) mitomycin-C treated DBA cells). This elevation of CLP-U persisted in the injected mice for at least 14 days. Control peptide did not affect CLP-U. In vitro incubation of 0.01 to 0.1 ng/ml of TP5 with normal C57BL/6 spleen cells also enhanced CLP-U after suboptimal allogeneic stimulation; high concentrations of TP5 caused suppression of CLP-U and this was detectable with optimal sensitization conditions. Thus TP5, in vitro and in vivo, appears to regulate immune responsiveness and this regulation varies with TP5 dosage and with the immune stimulus.     

Increase in liver acid lipase of thyroidectomized rats by thyroid hormones and its inhibition by actinomycin D.

Acid lipase activity in the livers of thyroidectomized rats is increased by administration of L-thyroxine. The response is dose-dependent and can be demonstrated within 12 h after treatment. L-Triiodothyronine also evokes a rapid increase in acid lipase activity, and this increase can be inhibited by coadministration of actinomycin D.