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M Webb

Publications and source records attributed to M Webb.

At least 145 records · Page 8Linked to original sources
PubMed1984

Recognition by a mouse monoclonal antibody of a glycoprotein antigen of rat brain which is expressed intracellularly by neurons.

We describe a previously uncharacterised glycoprotein antigen of rat brain. The antigen was localised by immunofluorescence on 10 micron cryostat tissue sections, and was found to be present intracellularly in neurons. No other cell types or structures within the brain were stained. The antigen is recognised by a mouse monoclonal antibody called NGP41. The antibody was produced after immunising a mouse with glycoproteins purified by lentil lectin affinity chromatography of solubilised rat brain membranes. Spleen cells from the immunised mouse were fused with the myeloma P3X63Ag8. The antigen is expressed by neurons in all brain regions, and also in the dorsal root ganglion neurons of the peripheral nervous system. In all brain regions, the large projection neurons are the most intensely stained by immunofluorescence, but some small neurons also express the antigen. Although dendrites were not stained, sections of sciatic nerve were stained by NGP41, suggesting that the antigen is expressed by axonal processes. The cell bodies of neurons in the inferior olive were stained by NGP41, but their terminals on Purkinje cell dendrites in the cerebellar cortex were not stained, suggesting that the antigen is absent or expressed below the limit of detection in terminals. Both crude brain membranes and a lentil lectin affinity purified brain glycoprotein fraction absorbed the antibody, suggesting that the antigen is a membrane bound glycoprotein. In immunoblotting experiments, the antigen was detected in homogenates of brain and spinal cord membranes, where it appeared as a triplet of bands with molecular weights of 41K, 38K and 36K. Antigen was not detected by immunoblotting in homogenates of six different tissues of non-nervous origin. The antigen was enriched in glycoprotein fractions from adult and juvenile cerebellum as assessed by immunoblotting. Adult brain glycoprotein preparations had a triplet structure similar to that in the homogenates, although most of the antigenic activity of the juvenile preparation was found in a position corresponding to the upper two bands of the triplet.

Animals↗
PubMed1984

The teratogenicity of methoxyacetic acid in the rat.

Intraperitoneal (i.p.) administration of methoxyacetic acid (MAA) to rats on Day 8, 10, 12 or 14 of pregnancy was embryolethal and teratogenic. Skeletal anomalies, hydrocephalus and dilatation of the kidney pelvis were the most common malformations. Embryonic response to MAA varied with gestational age and with dosage (0.1 to 2.5 mmol/kg). These actions are similar to those previously reported for 2-methoxyethanol (ME) and dimethoxyethyl phthalate (DMEP). Embryos were also examined on Day 12, 48 h following i.p. administration of 2.5 mmol/kg MAA. Abnormalities were comparable to those previously observed following MAA treatment of rat conceptuses in culture. These data support the conclusion that MAA is the proximal teratogenic metabolite of ME and DMEP.

Abnormalities, Drug-Induced↗
PubMed1984

Effects of dimethoxyethyl phthalate, monomethoxyethyl phthalate, 2-methoxyethanol and methoxyacetic acid on post implantation rat embryos in culture.

The secondary metabolite of dimethoxyethyl phthalate (DMEP), methoxyacetic acid (MAA), but neither the diester nor either of its primary metabolites, monomethoxyethyl phthalate (MMEP) and 2-methoxyethanol (ME), interferes with normal growth and development of organogenesis phase rat embryos in culture. These in vitro observations suggest that the teratogenicity of DMEP in vivo is due to enzymic cleavage of the diester to ME, followed by oxidation of the latter to MAA in the maternal compartment.

Acetates↗
PubMed1984

Localisation of the MRC OX-2 glycoprotein on the surfaces of neurones.

The MRC OX-2 monoclonal antibody recognises membrane glycoproteins of Mr 41,000 in rat brain and 47,000 on thymocytes. It also reacts with follicular dendritic cells in lymphoid organs, endothelium, smooth muscle, and B-lymphocytes. Indirect immunoperoxidase staining of cryostat sections showed that OX-2 antigen was present throughout the cerebellum, with staining of both grey and white matter. Blood vessels were also stained. The Purkinje cell layer appeared to be unlabelled. Double-immunofluorescence staining of cerebellar interneurone cultures with MRC OX-2 antibody and tetanus toxin showed that all tetanus-positive cells (neurones) were MRC OX-2-positive. Glial fibrillary acidic protein-positive astrocytes were not labelled by MRC OX-2 antibody. Thus OX-2 antigen is one of the few biochemically characterised components of neuronal membranes and its properties are compared with those of the neuronal membrane glycoprotein Thy-1.

Animals↗
PubMed1984

Cloned human teratoma cells differentiate into neuron-like cells and other cell types in retinoic acid.

Single cell clones were isolated from the human teratoma line, Tera-2. The cells of three of these clones were studied. The progressively growing cells were shown to be tumorigenic, and they were characterized by the lack of expression of beta 2-microglobulin and HLA-A,B,C determinants on the cell surface. The majority of the cells expressed Thy-1 antigen and a 90 X 10(3) molecular weight protein recognized by the monoclonal antibody F10.44.2; between a third and half of the cells expressed the sugar specificities detected by the anti-SSEA-1 monoclonal antibody. In response to 5 X 10(-5) M-retinoic acid applied to cells in monolayer culture, the cells differentiated into a population of flat static cells arrested in the G1 phase of the cell cycle. A substantial proportion of these differentiated cells expressed beta 2-microglobulin and 43 X 10(3) molecular weight HLA-A,B,C polypeptides, Thy-1, SSEA-1 sugar determinants, and the 90 X 10(3) Mr protein recognized by F10.44.2. The apparent molecular weight of fibronectin secreted by the cells decreased by about 5 X 10(3) Mr to 235 X 10(3) Mr after differentiation. The progressively growing cells lacked reactivity with reagents that mark cells in the nervous system. Following aggregation and retinoic acid treatment, neuron-like cells were formed. These cells reacted with reagents that also react with human neurons in culture: they reacted with tetanus toxin, the anti-neurofilament antibodies BF10 and RT97, the anti-ganglioside, GQ1c antibody F12 A2B5, and anti-Thy-1. The progressively growing cells of these Tera-2 clones are therefore capable of forming at least two types of cell: the flat cells in monolayer cultures and the neuron-like cells. None of the cell populations reacted with the monoclonal antibody against SSEA-3 and these cloned cells are therefore distinct from previous isolates from Tera-2.

Animals↗
PubMed1984

Capital financing through philanthropy.

Given the financial realities of the next few years, hospitals will need to look for new ways of raising capital. One often overlooked source is philanthropy. Rockingham Memorial Hospital (RMH) in Virginia has, since 1975, developed a particularly successful fund raising program. By dividing their donor base into a number of different categories, RMH is able to design and tailor a gifts campaign specific to each donor segment. Their development effort, including its conception, elements of success, and game plan is presented.

Financial Management↗
PubMed1983

Time-dependent uptake and metallothionein-binding of gold, copper and zinc in the rat kidney.

In rats, in which the whole body burden of Au decreases rapidly, but biphasically, maximum kidney concns are not attained until 10-15 days after a single intraperitoneal dose of either Au(I) or Au(III). The concn of metallothionein-bound Au and of total kidney Cu, which also increases after the administration of the Au compounds, however, reach maxima at 5 days. Between at least 6 and 24 hr after Au treatment, the increases in the concn of Au and Cu in the metallothionein fraction are highly correlated. Measurements on the kidneys of animals at early times (15 min-6 hr) after dosing with Au(III) indicate that the Zn content of the (endogenous) metallothionein is depressed during the first hour, shows a transient increase at 2 hr and then falls to a minimum at 6 hr. Subsequent (6-24 hr) changes in metallothionein-bound Zn parallel those of metallothionein-bound Au and Cu. It seems, therefore, that Au and Cu are incorporated simultaneously into rat kidney metallothionein and this incorporation may be mediated by an initial displacement of Zn. In rats exposed to five doses of Au(III) the half-times of total and metallothionein-bound Au in the kidneys are appreciably longer than those in animals given a single dose. In both groups, the concns of Cu and Zn in the renal metallothionein do not decrease in parallel with that of Au, but change roughly in proportion to their whole kidney concns. In consequence, the metal composition of the metallothionein fraction, which remains above the endogenous concn in the normal kidney throughout an experimental period of 90-140 days, alters considerably with time.

Animals↗
PubMed1983

88MHz 113Cd-n.m.r. studies of native rat liver metallothioneins.

Well-resolved 113Cd-n.m.r. spectra of 113Cd-induced rat liver metallothioneins 1 and 2 are obtainable even at 88 MHz (9.4T). The line-widths of resonances are not dominated by chemical-shift-anisotropy relaxation. The increased spectral dispersion will significantly aid the study of the native (Cd- and Zn-containing) metallothioneins.

Animals↗
PubMed1983

Cadmium-metallothionein-induced nephropathy: a morphological and autoradiographic study of cadmium distribution, the development of tubular damage and subsequent cell regeneration.

A single intravenous dose of 0.8 mg thionein-bound cadmium (Cd) per kg body weight, as the isolated (Cd, Zn)-metallothionein (MT) from rat liver, in rats of the same strain is nephrotoxic, but not lethal. Apical vesiculation in epithelial cells of the renal proximal convoluted tubules is apparent within 1 h of dosing and, by 4 h, is extensive in some of these cells that surround the larger arteries in the cortex. The membranes of these cells appear undamaged. The lesion at first progresses with time; by 24 h, the initially affected cells show extensive necrosis and most proximal convoluted tubular epithelia in other regions of the cortex are hydropically or vacuolarly degenerated. The inner stripe of the outer zone of the medulla and other portions of the nephron (glomerulus, distal tubule and collecting duct), however, appear essentially unaffected. The necrotic changes are maximal at 48 h but, after this time, regeneration begins. By seven days, much of the cell debris has been eliminated and cells of the regenerating or regenerated epithelia are similar in morphology to those of the normal kidney. Electron microscopic autoradiography of kidney sections from rats after administration of 109Cd-metallothionein of high specific activity shows that Cd is not concentrated in endocytotic vesicles, lysosomes, or any other cellular organelle, even at early times after dosing, but is distributed evenly throughout the epithelial cell. Thus, although Cd-MT appears to be taken up endocytotically in the kidney tubules, it appears that liberation of Cd from the metalloprotein must occur very early in the reabsorptive process.

Animals↗
PubMed1983

Embryotoxicity and teratogenicity of thalidomide in rats.

The teratogenicity of thalidomide in Wistar rats was investigated after a single maternal intravenous injection during the organogenetic period. Thalidomide was administered at 45 mg/kg in 0.5 ml dimethylformamide (DMF) on day 10, 11, or 12 of the pregnancy. Thalidomide induced skeletal deformities of thoracic ribs and of the spinal column in 33 and 56 percent of the fetuses upon maternal administration of the drug on day 11 or 12, respectively. As compared to the solvent (DMF) control, thalidomide caused two- to three-fold higher skeletally malformed fetuses. Deformities of the eyeball in fetuses (ophthalmorrhexis and microphthalmia) were induced by the maternal administration of the drug on day 10 and 12. The solvent (DMF) failed to induce organ deformities. Thalidomide induced embryotoxicity (as measured by percent dead and resorbed fetuses), at a rate three to eight times higher than the DMF control and represented 11 to 24 percent of dead and resorbed fetuses in thalidomide treated groups as compared to three percent in the DMF control group. Mean fetal weight was significantly reduced after maternal administration of thalidomide on day 11 of pregnancy, as compared to the DMF control. These studies conclude that thalidomide is teratogenic and embryotoxic in rats, when administered intravenously at 45 mg/kg bw.

Abnormalities, Drug-Induced↗
PubMed1983

The isolation of an antimycin A-resistant human cell line.

An antimycin A-resistant derivative of the human cell line, D98, has been obtained by selective mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. The derivative, designed MA65, is capable of continuous growth in 15 microM antimycin and the resistant phenotype is stable in the absence of selection. MA65 is not cross-resistant to chloramphenicol or triethyl tin. Crude membrane preparations from MA65 after propagation in medium containing antimycin have normal succinate-cytochrome c oxidoreductase activity and the respiratory activity of whole cells continues in the presence of the drug. The mitochondrially synthesized proteins of D98 and MA65 are similar when compared on sodium dodecyl sulphate (SDS), or isoelectric focusing gels, but there is a reproducible difference in the extent of labelling of one band detected by isoelectric focusing. Genetic analysis is consistent with the existence of a cytoplasmically localized determinant conferring resistance.

Antimycin A↗
PubMed1983

Observations on rat cerebellar cells in vitro: influence of substratum, potassium concentration and relationship between neurones and astrocytes.

We present data on the effect of elevated concentrations of K+ ions (25 mM) and polylysine (PLL) coating of the substratum on the in vitro survival and behaviour of cells derived from 8-day-old rat cerebellum. The cells were grown in Eagle's basal medium in the presence of 10% foetal calf serum and cytosine arabinoside (10 microM), as a mitotic inhibitor. The most conspicuous effect of the high potassium was to facilitate the relatively long survival of the nerve cells, whereas PLL influenced the nerve cell attachment and thereby the size of the aggregates formed in the cultures. When cells were grown in high [K+] on PLL-coated dishes (standard conditions) over 70% of the plated cells survived beyond 7 DIV, and about 95% of the cells were small interneurones, tentatively identified as predominantly granule cells. The most numerous non-neuronal cells were glial fibrillary acid protein (GFA) positive astrocytes. The beneficial effect of high potassium on nerve cell survival was most prominent after 7 DIV, when it is known that transmission-associated neurochemical functions are just becoming detectable under the standard conditions. Initially (at 3 DIV) under all the tested conditions, and throughout the experimental period under the standard conditions, the dominant type of GFA-positive cells was the process bearing 'differentiated' astrocyte. When the conditions resulted in a great decrease in nerve cell numbers, on the other hand, flat astroblast-like cells became the most abundant cells in this class. Neurones grown on polylysine in the presence of 25 mM potassium extended neurites as early as 6 h after plating, and with longer culture times, an extensive network of fibres of neuronal origin was generated. Neurites did not seem to follow the processes of GFA-positive astrocytes in the cultures. Although there was a limited tendency for neuronal cell bodies to be positioned around astrocytes at 1 DIV, this became less marked with time, and no preferential association between astrocytes and neurones could be detected in the cultures later than 2 DIV.

Animals↗
PubMed1983

Cell surface sialoglycoproteins of cultured rat cerebellar interneurons.

The sialoglycoproteins of cultures of relatively pure rat cerebellar interneurons were labelled by NaIO4 oxidation/NaB 3H4 reduction. The labelled molecules were analysed by polyacrylamide gel electrophoresis in sodium dodecyl sulphate followed by fluorography. Faint labelling could be detected in three components if cells were labelled without any oxidation. In young cultures, oxidation by galactose oxidase alone failed to reveal any additional bands. After oxidation by NaIO4 or galactose oxidase in the presence of neuraminidase, many more components were labelled. After NaIO4 oxidation, about 80% of the cell-associated radioactivity could be removed by treating the cells with neuraminidase, which left the cells more than 95% viable. The majority of the bands seen after neuraminidase treatment were substantially reduced when compared with untreated controls, supporting a surface localisation of these molecules. Reproducible developmental changes were seen in the profiles of bands labelled by NaIO4/NaB 3H4 in time course studies of cultures up to 8 days in vitro. Some bands became more prominent, and others disappeared. The gel profiles of the neuron cultures were quite distinct from those of cerebellar astrocyte cultures, which contain all the cell types likely to be contaminants of the neuron cultures.

Animals↗