Biomedical subjects

L G Green

Publications and source records attributed to L G Green.

8 recordsLinked to original sources

PubMed2000

Synthesis of high-mannose type neoglycolipids: active targeting of liposomes to macrophages in gene therapy.

The concise synthesis of five biantennary oligomannose neoglycolipids is presented. Employing a strategy based on the principles of reactivity tuning and orthogonal activation, the oligomannose moieties, isolated from the glycoprotein 63 of the parasite Leishmania mexicana amazonensis, were rapidly assembled taking advantage of common structural motifs found in these N-glycans. Deprotection of all structures was achieved in high yield by hydrogenolysis. The deprotected glycoconjugates were subsequently coupled to a cholesteroldiamine derivative using diethylsquarate as a linker. The resulting neoglycolipids will be used as additives to cationic liposome formulations in the active targeting of liposomes to macrophages.

Carbohydrate Sequence↗

PubMed2000

1,2-Diacetals in synthesis: total synthesis of a glycosylphosphatidylinositol anchor of Trypanosoma brucei.

A full account on a total synthesis of GPI anchor 1 employing butanediacetal (BDA) groups and a chiral bis(dihydropyran) is presented. The reactivity of selenium and thio glycosides was tuned by the use of BDA groups. This allowed the assembly of an appropriately protected GPI anchor precursor 2 in just six steps from the six building blocks 5-10 including only one protecting group manipulation. myo-Inositol was desymmetrised with the bis(dihydropyran) derivative 15 and appropriately protected to give inositol acceptor 21 in nine steps and 17% overall yield. The use of common starting materials and BDA-protections give efficient access to building blocks 5, 6, 7 and 8. A new and improved synthesis of the glucosamine donor 28 is included. In summary, a highly convergent and efficient synthesis of GPI anchor 1, which is clearly adaptable to other GPI anchors, has been reported.

Animals↗

PubMed2000

Chemoenzymatic synthesis of L-galactosylated dimeric sialyl Lewis X structures employing alpha-1,3-fucosyltransferase V.

L-Galactosylated dimeric sialyl Lewis X (SLeX) has been prepared employing a combination of chemical and enzymatic synthetic methods. GDP-L-galactose has been chemically synthesised. Enzymatic transfer of L-galactose onto the acceptor (Sia-alpha2,3-Gal-beta1,4-GlcNAc-beta1,3/6)2-Man-alpha1-OMe was achieved using the human alpha-1,3-fucosyltransferase V.

Carbohydrate Sequence↗

PubMed2000

Evaluation of lymph node virus burden in human immunodeficiency virus-infected patients receiving efavirenz-based protease inhibitor--sparing highly active antiretroviral therapy.

Although efavirenz-containing regimens effectively suppress plasma levels of human immunodeficiency virus (HIV) RNA, it is now clear that undetectable plasma viremia may not reflect a lack of viral replication. Because lymphoid tissue is an active site of HIV replication, the lymph node virus burden was analyzed in persons who received highly active antiretroviral therapy (HAART) containing either efavirenz or a protease inhibitor (PI). Testing with in situ hybridization revealed no detectable follicular dendritic cell-associated HIV RNA in either group, and only 2 of 8 persons in the efavirenz group and 1 of 4 in the PI group had detectable RNA in lymph node mononuclear cells (LNMC) when tested by use of nucleic acid sequencebased amplification. Low levels of replication-competent HIV were identified in both groups by use of quantitative coculture assays. There was no evidence of development of resistance to either regimen in virus isolated from LNMC. These data support the use of efavirenz as an alternative to a PI in initial HAART regimens.

Alkynes↗

PubMed1992

Association of 70-kilodalton heat-shock cognate proteins with acclimation to cold.

Exposure of young spinach seedlings (Spinacia oleracea L. cv Bloomsdale) to 5 degrees C leads to an increase in the synthesis of several 79-kilodalton proteins that are present in leaf tissue grown at 20 degrees C. Protein sequence analyses and immunological cross-reactivity indicate that this group of proteins belongs to the 70-kilodalton heat-shock family. Steady-state transcript levels and protein synthesis are increased two- to threefold within 1 day, but immunoblot analyses suggest that the steady-state concentration of this protein group in leaf tissue only gradually accumulates at low temperature. It is proposed that the increased synthesis of several members of the 70-kilodalton heat-shock family could result from an influence of low temperature on protein folding and/or assembly processes.

Journal Article↗

PubMed1986

Human histone genes map to multiple chromosomes.

Histone genes were mapped to at least three human chromosomes by Southern blot analysis of DNAs from a series of mouse-human somatic cell hybrids (using 32P-labeled cloned human histone DNA as probes). Chromosome assignment was confirmed by in situ hybridization of radiolabeled histone gene probes (3H-labeled) to metaphase chromosomes. One human histone gene cluster (lambda HHG41) containing an H3 and H4 gene resides only on chromosome 1, whereas other clusters containing core (H3, H4, H2A, and H2B) alone (lambda HHG17) or core together with H1 histone genes (lambda HHG415) have been assigned to chromosomes 1, 6, and 12. These results suggest that the multigene family of histone coding sequences that reside in a series of clusters may be derived from a single cluster containing one each of the genes for the five principal classes of histone proteins. During the course of evolution, a set of events, probably involving reduplication, sequence modification, and recombination, resulted in the present pattern of human histone gene distribution among several chromosomes.

Biological Evolution↗

PubMed1984

Influence of delta 9-tetrahydrocannabinol on expression of histone and ribosomal genes in normal and transformed human cells.

The influence of delta 9-tetrahydrocannabinol (delta 9-THC) on the cellular levels of histone mRNAs and ribosomal RNAs was examined in several normal and transformed human cell lines--HeLa S3 cells, WI-38 human diploid fibroblasts, SV40-transformed WI-38 cells, and A549 lung carcinoma cells. RNA sequences were quantitatively assayed by electrophoretic fractionation, transfer to nitrocellulose, and hybridization with cloned genomic human histone or ribosomal DNA sequences. Treatment with delta 9-THC (10-40 microM) for 10 hr resulted in a concentration-dependent decrease in the representation of H2A, H2B, H3 and H4 histone mRNAs without a significant inhibitory effect on the levels of ribosomal RNAs. The cannabinoid-mediated inhibitory effect on histone gene expression was less evident in cells with active drug-metabolizing systems.

Base Sequence↗

PubMedDate not supplied

A decreased influence of cannabinoids on macromolecular biosynthesis and cell proliferation in human cells which metabolize polycyclic hydrocarbon carcinogens.

The influence of psychoactive and nonpsychoactive cannabinoids on macromolecular biosynthesis and cell proliferation was compared in normal and transformed human cells which differ with respect to their abilities to metabolize polycyclic hydrocarbon-containing carcinogens. delta 9-THC, delta 8-THC, 11-OH-delta 9-THC, cannabinol and cannabidiol cause a dose-dependent inhibition of [3H]thymidine, [3H]uridine and [3H]leucine incorporation and a dose-dependent inhibition of cell growth in both normal and transformed human cells. The effectiveness of cannabinoids in modifying nucleic acid biosynthesis, protein biosynthesis, and cell growth does not appear to be related to expression of the transformed phenotype; however, cells with enhanced drug metabolizing capacities, including abilities to metabolize polycyclic hydrocarbon-containing carcinogens, are significantly less sensitive to cannabinoid-induced effects on macromolecular biosynthesis and cell growth.

Cannabinoids↗