Search PubMed⌕ Search

Biomedical subjects

M J Anderson

Publications and source records attributed to M J Anderson.

At least 145 records · Page 8Linked to original sources
PubMed1983

Aplastic crisis due to parvovirus infection in pyruvate kinase deficiency.

A thirteen-year-old boy with congenital haemolytic anaemia due to pyruvate kinase (PK) deficiency had an aplastic crisis. A serum parvovirus-like virus (SPLV) was demonstrated in the blood by electron microscopy and, subsequently, IgM and IgG antibodies to the prototype SPLV B19 were detected. In an attempt to define the level of erythropoiesis that is involved in parvovirus-induced bone marrow suppression, the levels of circulating early erythroid progenitors (burst forming units erythroid, BFU-E) were monitored during the crisis and recovery period. The virus-containing plasma inhibited the formation of BFU-Es from non-immune subjects and this effect was neutralised by convalescent serum. Colony forming units granulocyte-macrophage (CFU-GM) were also inhibited but this was probably non-specific since neutralisation did not reverse the effect. These experiments, together with the clinical data, suggest a selective effect of SPLV at the stage of erythroid progenitors.

Adolescent↗
PubMed1983

Fine structure of regenerated ependyma and spinal cord in Sternarchus albifrons.

The caudal-most regenerated spinal cord in Sternarchus albifrons consists solely of an ependymal tube. Ependymal cells are enlarged radially and are more numerous than in unregenerated cord. Projections of ependymal cell cytoplasm and Reissner's fiber fill most of the central canal. Small groups of neurites and cell processes filled with dense-cored vesicles lie between abluminal processes of ependymal cells. Rostral to this, additional cells appear dorsal and lateral to the inner ependymal layer. Some cell bodies contain numerous dense-cored vesicles. Larger bundles of neurites, some with synapses, are present. Invaginations of the peripheral edge of the cord create enclosed spaces lined with basal lamina. In the peripheral region, longitudinally oriented neurites extend through extracellular spaces or channels. The ventral portion at some levels of regenerated cord is completely filled with neurites, processes containing dense-cord vesicles, and capillaries. Similar masses of neurites and processes containing dense-cored vesicles lie outside the cord proper, in or near the meningeal layer. In rostral-most sections, the organization of regenerated spinal cord approaches that of normal cord, with the regenerated cord exhibiting groups of myelinated axons, differentiated fibrous astrocytes and oligodendroglia, cell bodies containing dense-cored vesicles, and differentiated electromotor neurons. These observations indicate a degree of pluripotency in some of the ependymal cells in adult Sternarchus. Moreover, they are consistent with a role of ependymal cells in the guidance of regenerating neurites.

Animals↗
PubMed1983

Caudal spinal cord of the teleost Sternarchus albifrons resembles regenerating cord.

The morphology of spinal cord in the caudal-most spinal segments of normal adult Sternarchus albifrons is different from that of more rostral adult cord. The caudal segments are strikingly similar to the regenerating spinal cord observed after amputation of the tail in Sternarchus. In the caudal-most vertebral segment of normal spinal cord, ependymal cells are radially enlarged and are more numerous than in more rostral adult cord. Large processes of the ependymal cells extend into the central canal, which also contains a prominent Reissner's fiber. Invaginations of the outer surface of the spinal cord, with the associated basal lamina, are common. Lateral to the immediate ependymal layer, extracellular spaces contain longitudinally oriented neurites. Cell bodies and cell processes filled with dense-cored vesicles occur throughout the caudal-most segment of spinal cord, and are especially concentrated in the ventral half, interspersed with numerous capillaries. In all these respects the caudal-most segments of normal adult spinal cord in Sternarchus closely resemble regenerating spinal cord of Sternarchus. In both regions, at least some of the ependymal cells retain the ability to divide and generate new neurons and glial cells.

Animals↗
PubMed1983

Aggregates of acetylcholine receptors are associated with plaques of a basal lamina heparan sulfate proteoglycan on the surface of skeletal muscle fibers.

Hybridoma techniques have been used to generate monoclonal antibodies to an antigen concentrated in the basal lamina at the Xenopus laevis neuromuscular junction. The antibodies selectively precipitate a high molecular weight heparan sulfate proteoglycan from conditioned medium of muscle cultures grown in the presence of [35S]methionine or [35S]sulfate. Electron microscope autoradiography of adult X. laevis muscle fibers exposed to 125I-labeled antibody confirms that the antigen is localized within the basal lamina of skeletal muscle fibers and is concentrated at least fivefold within the specialized basal lamina at the neuromuscular junction. Fluorescence immunocytochemical experiments suggest that a similar proteoglycan is also present in other basement membranes, including those associated with blood vessels, myelinated axons, nerve sheath, and notochord. During development in culture, the surface of embryonic muscle cells displays a conspicuously non-uniform distribution of this basal lamina proteoglycan, consisting of large areas with a low antigen site-density and a variety of discrete plaques and fibrils. Clusters of acetylcholine receptors that form on muscle cells cultured without nerve are invariably associated with adjacent, congruent plaques containing basal lamina proteoglycan. This is also true for clusters of junctional receptors formed during synaptogenesis in vitro. This correlation indicates that the spatial organization of receptor and proteoglycan is coordinately regulated, and suggests that interactions between these two species may contribute to the localization of acetylcholine receptors at the neuromuscular junction.

Animals↗
PubMed1983

Characterization of the genome of the agent of erythrocyte aplasia permits its classification as a human parvovirus.

It has recently been established that infection with a virus is the most common cause of transient arrest of erythrocyte production in the bone marrow, leading to aplastic crisis, in persons suffering chronic haemolytic anaemias. The physical characteristics of this human virus have suggested that it may be a member of the Parvoviridae. We report here that extraction of nucleic acid from this virus under annealing conditions yielded a single species of double-stranded DNA 5.5 kb in length. Treatment with heat or alkali converted this DNA into a rapidly migrating form sensitive to the single-strand-specific nuclease S1. Extraction of the virion DNA under conditions of low ionic strength where annealing would not be expected to occur yielded DNA which comigrated with the 5.5 kb single-stranded molecule. The results indicate that this virus packages equal numbers of complementary DNA strands into separate virions. It is suggested that this virus can be classified as a member of the genus parvovirus.

Anemia, Hemolytic↗
PubMed1983

Infection with parvovirus-like virus and aplastic crisis in chronic hemolytic anemia.

From 1980 to 1982 seven adults with chronic hemolytic anemia were admitted to Cook County Hospital, Chicago, with aplastic crisis. Six of these patients had sickle cell anemia, the seventh patient had beta thalassemia intermedia. Virologic studies showed that six patients had acute infection with the human parvovirus-like virus; in the remaining patient the lack of appropriate specimens precluded viral diagnosis. We describe the features of the virus infection and accompanying erythroid aplasia, and discuss the role of parvovirus-like virus as the etiologic agent in the arrest of erythrocyte production.

Adolescent↗
PubMed1983

Regeneration of spinal neurons in inframammalian vertebrates: morphological and developmental aspects.

This review discusses regeneration of spinal neurons in inframammalian vertebrates. In contrast to the limited regeneration of nerve fibers in mammalian spinal cord, relatively complete regeneration of spinal cord, including the formation of new neurons, occurs in cyclostomes, selachians, teleosts, and urodele amphibians. The various experimental techniques which have been used to accelerate or enhance regeneration of spinal cord, such as implantation of peripheral nerve bridges, application of growth factors or chemical agents, and the application of exogenous electrical fields, are discussed. Processes involved in regeneration of other systems, e.g., the trophic effect of nerve fibers, the effect of certain hormones, and the effects of the blastema, are discussed as they may relate to regeneration in the spinal cord. Recent work on the factors which influence nerve outgrowth is discussed. Factors such as diffusible chemical gradients, contact with other cells, pre-formed channels for nerve growth, and differences in adhesivity of neurites for the substratum may act to control the direction of axon outgrowth in regeneration as well as normal embryonic development. This article next reviews work from our laboratory on regeneration of spinal neurons in the teleost, Sternarchus albifrons. We have used Sternarchus as a model system for the study of regeneration and remyelination since: 1. spinal cord readily regenerates after amputation of the tail, 2. new nerve cell bodies are formed during this regeneration, and 3. Sternarchus contains large neurogenic electric organs which also regenerate after tail amputation. The axons of the electric organ arise from spinal neurons and have a highly specific and complex morphology which is recapitulated after regeneration. Studies on Sternarchus indicate that new nerve cell bodies are produced during regeneration from the enlarged ependymal cells. Initially, many more of the electromotor neurons are produced in regenerated spinal cord than are present normally. Cell death subsequently occurs in some of these asynaptic cells, reducing the number of electrocytes in older regenerated cord to a more normal condition. The spinal electromotor neurons in Sternarchus have also been used to demonstrate that section of the axon in an asynaptic neuron will produce a typical "axon reaction" in the cell body. It is interesting that cell death during regeneration and the retrograde axon reaction both appear to occur without loss of synaptic elements in these normally asynaptic cells. Neurites grow through regenerating Sternarchus spinal cord in small bundles, in close contact with adjacent ependymal cell processes. Longitudinal channels, filled with neurites, are seen extending through many stages of regenerating Sternarchus cord, usually near the periphery of the cord. There are numerous invaginations of the peripheral edge of regenerating cord and its associated external lamina. These infoldings may be involved in the generation of the neurite filled channels.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1982

Retrograde axon reaction following section of asynaptic nerve fibers.

The asynaptic spinal neurons of the gymnotid teleost Sternarchus albifrons show several distinct characteristics of the retrograde reaction of the perikaryon (which corresponds to chromatolysis in mammals) following axotomy. Nuclei of affected cells are characteristically eccentric. Large bundles of neurofilaments, never seen in normal perikarya of these cells, become prominent following axotomy. There is a marked increase in the number and size of dense bodies in the affected perikarya. Large arrays of parallel rough endoplasmic reticulum, never seen in normal cells, are frequent in the axotomized neurons. These results demonstrate that disconnection from synaptic terminals is not a necessary condition for the retrograde reaction of the perikaryon following axotomy.

Animals↗
PubMed1982

The development and use of an antibody capture radioimmunoassay for specific IgM to a human parvovirus-like agent.

An IgM-antibody capture radioimmunoassay (MACRIA) was developed for the detection of IgM antibody specific for the human parvovirus-like agent B19. Diagnosis of infection with this agent by either antigen detection or antibody seroconversion had been made by counter-current immunoelectrophoresis (CIE) in 18 cases of aplastic crisis occurring in children with homozygous sickle-cell disease. The MACRIA described here gave positive results in 17 of these 18 cases; in the remaining case only an acute specimen taken from the patient during viraemia and late convalescent specimens taken 184 and 247 days after onset of illness were available. The test was used to investigate 20 further cases of aplastic crisis in which neither viral antigen nor antibody seroconversion could be detected by CIE. Detection of virus-specific IgM permitted diagnosis of infection with this parvovirus-like agent in 17 of these cases. In the remaining three cases only single serum specimens taken late in convalescence, 82 days or more after the onset of symptoms, were available. In addition to these 34 cases of aplastic crisis in which primary infection with this agent was diagnosed by MACRIA, seven cases of apparent 'silent' infection detected by CIE were investigated. The test permitted the discrimination between primary infection and re-exposure to the virus in six of these patients. The use of this assay has added a considerable weight of evidence implicating primary infection with this parvovirus-like agent as an important cause of aplastic crisis in children with sickle-cell disease. Furthermore, MACRIA permits diagnosis of infection when only single serum specimens taken up to ten weeks after infection are available. Thus the use of this test will significantly facilitate the investigation of other clinical syndromes of presumptive infectious aetiology.

Adult↗
PubMed1982

The production of monoclonal antibodies to rubella haemagglutinin and their use in antibody-capture assays for rubella-specific IgM.

Mice were immunized by three intraperitoneal and one intravenous injection of rubella haemagglutinin. Splenocytes from these mice were fused with the cells of a syngeneic myeloma cell line, and following culture for various periods of time, single-cell clones were derived by the technique of limiting dilution. A total of 139 clones were derived from 13 parent hybrid cultures. To date, four of these cloned cultures have been propagated as ascitic tumours in mice. The preparation of IgG from ascitic fluid and labelling of this antibody with 125I is described. Results indicate that the use of labelled monoclonal antibodies as indicator reagents in solid-phase IgM antibody capture assays for the detection of rubella-specific IgM results in enhanced performance of these tests.

Animals↗
PubMed1982

The role of interferon in the NK cell killing of virus-infected target cells.

Spleen cells from uninfected CBA mice are more cytotoxic for Sendai virus-infected L929 cells than for uninfected cells and the lymphocytes responsible have the properties of NK cells. Preincubation of spleen cells with culture supernatants from Sendai virus-infected L929 cells increases the cytotoxicity for uninfected target cells. This increase in cytotoxicity can also be produced by pretreatment with purified mouse interferon. The enhancing effect of both the infected culture supernatants and purified interferon can be neutralized with anti-interferon serum. It is concluded that the preferential killing of Sendai virus-infected L929 cells by NK cells is dependent on the induction of interferon and that interferon will increase NK cell cytotoxicity for uninfected target cells.

Animals↗
PubMed1982

Occurrence of infection with a parvovirus-like agent in children with sickle cell anaemia during a two-year period.

The occurrence of infection with a parvovirus-like agent during the period April 1979-May 1981 in children attending a single sickle cell clinic in London was investigated. Virus was detected in serum by counter-current immunoelectrophoresis (CIE) and immunoelectron microscopy (IEM). Viral antibody was detected by CIE and specific IgM antibody by an IgM-antibody capture assay. Of the 68 children studied nine presented in aplastic crisis and evidence of infection with the parvovirus-like agent at the time of the crisis was found in all nine. Eighteen of the other children were antibody-positive at some time during the study. In 11 children there was no evidence of recent infection; however, two of these had a history of aplastic crisis in previous years. The other seven seroconverted during the course of the study but did not show any haematological effects. Five of these had a primary infection, one appeared to have reinfection and in the seventh there were insufficient data to distinguish between the two. Possible explanations for the difference between those presenting with aplastic crisis and those with asymptomatic seroconversion are discussed.

Anemia, Sickle Cell↗
PubMed1981

Morphology of regenerated spinal cord in Sternarchus albifrons.

The tail of the gymnotid Sternarchus albifrons, including the spinal cord, regenerates following amputation. Regenerated spinal cord shows a rostro-caudal gradient of differentiation. Cross sections of the most distal regenerated cord show radially enlarged ependymal cells, relatively undifferentiated cells, and numerous blood vessels. More anterior sections contain well differentiated electromotor neurons, glial cells, and myelinated axons. The number of electromotor-neuron cell bodies in cross sections of regenerated spinal cord is three to six times the number in nonregenerated cord. Distinct tracts of axons, easily identifiable in normal cord, are not distinguishable in cross sections of regenerated cord. Some reorganization of the spinal cord also appears to take place anterior to the site of transection. Individual electromotor neurons in the regenerated spinal cord have morphologies largely similar to those of normal electrocytes, i.e., cell bodies are rounded, lack dendrites, have synapses characterized by gap junctions with presynaptic axons, and lack an unmyelinated initial segment. The presence of electromotor neurons with normal morphology in regenerated spinal cord correlates with the re-establishment of relatively normal electrocyte axon-Schwann cell relationships in the regenerating electric organ of this sternarchid.

Animals↗
PubMed1981

Patterns of antibody reactivity against selected human leukemia cell lines.

Absorption procedures which allow the production of a selectively cytotoxic anti-human lymphocyte serum are described. Although the production of a reagent whose reactivity is restricted. Although the production of a reagent whose reactivity is restricted exclusively to lymphocytes may be achieved by exhaustive absorption steps using fresh human erythrocytes, CML cells, and fetal liver cells, a more realistic alternative is the use of appropriately selected cultured human leukemia cell lines. Data are presented which show how these cell lines may be employed to selectively manipulate the cross-reactivity spectrum of ALS. Pre-treatment of donor bone marrow cells prior to transplantation with a selectively lymphocytotoxic ALS has been shown to allow transplantation of bone marrow across major histocompatibility barriers in rodents without the occurrence of GvH reactions, and it is the purpose of the present investigations to show that an analogous anti-human ALS can be prepared which possesses the required degree of selectivity to allow its application for human bone marrow transplantation.

Antilymphocyte Serum↗
PubMed1981

Cell separation by antibody-coupled magnetic microspheres and their application in conjunction with monoclonal HLA-antibodies.

The modification and efficiency of a technique for cell separation is described. This technique combines the specificity of serologic reactions with the strength and physical selectivity of a magnetic field. A monoclonal HLA-BW 6 antibody was coupled to 100 nm diameter Fe3O4 containing albumin microspheres via surface-incorporated St. aureus Protein-A. The mixture of HLA-BW 6 and -BW 4 human peripheral blood lymphocytes was incubated with these immunomicropheres and applied to a glass column located in a magnetic field. Only HLA-BW 4 lymphocytes passed through the column and were collected. The recovered cells were 97% viable.

Antibodies, Monoclonal↗