Expression and capping of a proliferation-associated surface membrane p34 kDa antigen on different human hematopoietic cell lines

A novel surface membrane nonglycosylated acidic polypeptide (34 kDa), encoded by a structural gene on chromosome 11, has been identified using murine monoclonal antibody (MoAb) 53.6 (IgG2a). MoAb 53.6, raised against uninduced cells of a human erythroleukemia line (HEL), recognizes a surface membrane antigen that is displayed on proliferating (cell cycle phase G1, S, and M + G2 phase) human leukocytes. The expression and redistribution (i.e., patching and capping) of the p34 kDa antigen on 27 different long-term human hematopoietic cell (HHC) lines was defined by fluorescence microscopy. These lines had been established from patients with leukemia or healthy donors and included phenotypically defined populations of T cells, B cells, and myelomonocytic cells. Almost all (greater than 95%) of the leukocytes of the 27 lines reacted strongly with MoAb 53.6. The majority of the leukocytes displayed p34 kDa antigen patching (26/27 lines; patched cells, 96-100%); moreover, 20 of 27 lines exhibited p34 kDa antigen capping (capped cells, 8-96%). Presentation of the p34 kDa antigen on surface membrane ultrastructures, imaged with immunogold using an indirect antibody labeling procedure, was illustrated by scanning electron microscopy, and endocytosis of the gold-tagged antigen-antibody complex was studied by transmission electron microscopy. The HHC lines are thought to represent immortalized populations of different human leukocyte subsets that are in different stages of maturation and/or differentiation; thus these lines should prove useful as models for further characterizing this unique p34 kDa proliferation-associated antigen and for defining the mechanisms and significance of surface membrane antigen redistribution and modulation that has been associated with leukocyte activation and propagation.     

Using adiabatic inversion pulses for long-T2 suppression in ultrashort echo time (UTE) imaging.

Ultrashort echo time (UTE) imaging is a technique that can visualize tissues with sub-millisecond T(2) values that have little or no signal in conventional MRI techniques. The short-T(2) tissues, which include tendons, menisci, calcifications, and cortical bone, are often obscured by long-T(2) tissues. This paper introduces a new method of long-T(2) component suppression based on adiabatic inversion pulses that significantly improves the contrast of short-T(2) tissues. Narrow bandwidth inversion pulses are used to selectively invert only long-T(2) components. These components are then suppressed by combining images prepared with and without inversion pulses. Fat suppression can be incorporated by combining images with the pulses applied on the fat and water resonances. Scaling factors must be used in the combination to compensate for relaxation during the preparation pulses. The suppression is insensitive to RF inhomogeneities because it uses adiabatic inversion pulses. Simulations and phantom experiments demonstrate the adiabatic pulse contrast and how the scaling factors are chosen. In vivo 2D UTE images in the ankle and lower leg show excellent, robust long-T(2) suppression for visualization of cortical bone and tendons.     

Mapping the Von Hippel -- Lindau disease tumour suppressor gene: identification of germline deletions by pulsed field gel electrophoresis

Von Hlppel—Lindau (VHL) disease is a dominantly Inheritedfamillal cancer syndrome In which affected individuals havea greatly increased predisposition to the development of haemangloblastomasof the central nervous system and retina, renal cell carcinomaand phaeochromocytoma. The VHL gene has been mapped to chromosome3p25 -p26 by genetic linkage studies and we have previouslydemonstrated that the VHL gene is tightly linked to the D3S601locus (Zmax = 18.86 at     

A differential efficiency of adenovirus-mediated in vivo gene transfer into skeletal muscle cells of different maturity

High titre (10¹¹–10¹² pfu/ml) suspensions of autonomouslyreplication-defective type 5 human adenovirus (AV) recombinantswith different reporter gene inserts (CMV-Luciferase (Lux),CMV-ß-galactosidase (Lac Z), RSV-Lux and RSV-Lac Z)were injected Into intact quadrlceps muscles of 1–5 dayold (Group 1) or 35–45 day old (Group 2) normal mice,as well as regenerating adult mouse muscles (Group 3) and 35day old mdx muscles (Group 4). The expression of the reportergenes was quantitated 10 days and 2 months later. At 10 dayspostinjection all reporter gene expression was very high inthe neonatally injected (Group 1) muscles. In Group 2 musclesthe transduction was markedly less. In Group 3 muscles the geneexpression was significantly better than in the Group 2 muscles.In adult mdx muscles (Group 4) where spontaneous regenerationis usually present, the results were similar to those in Group3 animals. At 2 months post-injection in Group 1 animals, theRSV-Lux expression was even higher than at 10 days postinjection.The cell surface density of     

Synaptic targeting of N-methyl-D-aspartate receptor splice variants is regulated differentially by receptor activity

The formation of postsynaptic clusters of various ligand-gated ion channels is regulated by receptor activity. Here we describe the developmental- and activity-dependent modification of N-methyl-D-aspartate (NMDA) receptor clustering in spinal cord neurons in vitro detected by immunofluorescence analysis using subunit and splice variant specific antibodies. NMDA receptors form synaptic and extrasynaptic clusters with sequential changes in subunit composition during in vitro development. During the first week of in vitro culture, a NR1 splice variant containing the C2-carboxy terminus and lacking the N1-cassette and the NR2B subunit are the prevailing components of receptor clusters at synaptic and extrasynaptic sites. After 3 weeks in culture (days in vitro [DIV] 22), the numbers of postsynaptic receptor clusters with N1-containing NR1 splice variants and NR2A subunits are upregulated. At DIV22, C2-specific clusters are abundant and are predominantly localized at postsynaptic sites, whereas the total number of C2'-clusters in dendrites is much lower and these clusters are localized mostly extrasynaptically. However, upon chronic inhibition of NMDA receptor activity in DIV8 and DIV22 cultures with MK801, the number of postsynaptic NR1-C2' subunit clusters is strongly upregulated. In contrast, numbers of NR1-C2 clusters are only modestly increased in DIV8 and not changed in DIV22 cultures upon MK801 treatment, suggesting a specific role of NR1 carboxy-terminal sequences in the activity-dependent synaptic targeting of NMDA receptor clusters of spinal cord neurons.