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Biomedical subjects

M J Anderson

Publications and source records attributed to M J Anderson.

At least 127 records · Page 7Linked to original sources
PubMed1985

Neurogenesis in tissue cultures of adult teleost spinal cord.

[3H]Thymidine autoradiography of explant cultures from the spinal cord of an adult teleost, Sternarchus albifrons, reveals the presence of thymidine-labeled cells with neuronal morphology. These cells have also been identified as neurons by positive staining with two monoclonal antibodies against neurofilaments. Thymidine labeling occurs in cultured neurons derived from both normal (histologically and functionally mature) and regenerating spinal cord of adult Sternarchus albifrons. These results provide evidence that some cells in spinal cord of adult Sternarchus retain the ability to incorporate thymidine and undergo neuronal differentiation in vitro.

Animals↗
PubMed1985

Experimental parvoviral infection in humans.

Healthy adult volunteers were inoculated intranasally with human parvovirus obtained from an asymptomatic blood donor. One week after inoculation, intense viremia was observed in seronegative volunteers, accompanied by a mild illness with pyrexia, malaise, myalgia, itching, and excretion of virus from the respiratory tract. In the following week hematologic studies revealed reticulocytopenia with an associated slight drop in hemoglobin concentration, lymphopenia, neutropenia, and a drop in platelet counts. At 17-18 days after inoculation a second-phase illness with rash and arthralgia lasting three to four days occurred in three of four infected volunteers. This study confirms the etiologic role of human parvovirus in erythematous rash illness, with the second-phase illness being consistent with adult cases of erythema infectiosum. Moreover, the hematologic changes associated with infection support the hypothesis that the same virus is responsible for the temporary arrest of erythropoiesis that leads to aplastic crisis in persons with chronic hemolytic anemia.

Anemia, Hemolytic↗
PubMed1985

Neurogenesis in adult vertebrate spinal cord in situ and in vitro: a new model system.

Phylogenetically "lower" species in some cases use different biological strategies for recovery after injury to the CNS than do "higher" species. One approach that we have taken in our laboratory has been to study the mechanisms of functional recovery of the CNS after injury in those vertebrate species where recovery does occur. The present report reviews recent studies on a model system, the spinal electromotor system of the gymnotiform teleost Sternarchus albifrons, which exhibits regeneration and neurogenesis after injury. Regeneration in this system leads to a recapitulation of relatively normal morphologic structure by the damaged or extirpated spinal cord. In Sternarchus, new spinal cord is generated from ependymal cells; some ependymal cells in the adult remain pluripotent and retain the capability to generate new neurons. The Sternarchus spinal cord thus represents an especially useful model for the study of neurogenesis after injury to the CNS. Recent studies in our laboratory indicate that neurogenesis in adult Sternarchus spinal cord tissue occurs both in vivo and in vitro. Neurogenesis has been demonstrated by incorporation of tritiated thymidine into explant cultures from the spinal cord of adult Sternarchus. Autoradiography reveals the presence of thymidine-labeled neurons. Neuronal identity of 3H-labeled cells has been confirmed by positive staining with neuron-specific monoclonal antibodies. Thymidine labeling occurs in cultured neurons derived from both normal (histologically and functionally mature) and regenerating spinal cord of adult Sternarchus albifrons. These results provide evidence that some cells in spinal cord of adult Sternarchus retain the ability to incorporate thymidine and undergo neuronal differentiation in vitro. This system provides a new model in which neurogenesis from adult tissue can be studied in vivo and in vitro.

Aging↗
PubMed1985

Selective antilymphocyte sera (SAL) in bone marrow transplantation. I. In vitro characterization of antihuman SAL and the development of absorption procedures using cultured cell lines.

In experimental animals, graft-versus-host reactions can be prevented, even in fully MHC-allogeneic bone marrow transplantation (BMT) by in vitro elimination of mature T cells and their committed precursors from donor bone marrow with a selectively lymphocytotoxic heterologous antiserum. Application of this concept to clinical BMT has previously been hampered by the lack of antibodies of appropriately selective specificity. We describe here the production and characterization of highly selective lymphocytotoxic antisera against mature human T cells and lymphoid precursors using cultured cell lines.

Absorption↗
PubMed1985

Magnetic albumin/protein A immunomicrospheres. II. Specificity, reproducibility, and resolution of the magnetic cell separation technique.

Magnetically responsive albumin/protein A immunomicrospheres (MIMS) were prepared by reacting a mixture of albumin, iron oxide, and protein A in a two-phase emulsion coagulation procedure. The protein A ligand permits strong affinity binding of the monoclonal anti-HLA BW6 antibody to the 500-nm MIMS in a one-step process. HLA BW6+ and BW4+ human peripheral blood lymphocytes and mixtures of both were incubated with these MIMS. The findings obtained after only one run in a magnetic field were as follows: depletion of 98.6 +/- 0.9% of the target cells when 2 mg MIMS/10(6) cells were used, unspecific trapping of 5.9 +/- 2.5% of the nontarget cells from cell mixtures, and effective separation of cell populations as small as 1-0.1%. Thus, using albumin/protein A MIMS, the magnetic cell separation technique is simple, rapid, and highly sensitive.

Albumins↗
PubMed1984

Magnetic albumin/protein A immunomicrospheres. I. Preparation, antibody binding capacity and chemical stability.

We describe a method of preparing small magnetic microspheres of albumin/protein A, uniform in size, at 200, 300 or 500 nm. It is shown that, independent of size, the microspheres always carry iron peripherally in their matrix and are thus magnetically responsive. A quantitative antibody binding capacity of 82 micrograms/mg microspheres was established for the 500 nm microspheres. The microspheres are stable in most commonly used buffers over a pH range of 2.5-9.2, but are appreciably unstable in such concentrated denaturing agents as 3 M TCN-, 6 M guanidine, or 8 M urea (loss of antibody binding capacity, 30% for TCN- and 70% for urea).

Antibodies, Monoclonal↗
PubMed1984

Cell death of asynaptic neurons in regenerating spinal cord.

The weakly electric fish Sternarchus albifrons possesses a unique class of asynaptic neurons, the electromotor neurons, whose axons constitute the electric organ. The cell bodies of origin of the electrocyte axons are located in the spinal cord. Both spinal cord and electromotor neurons ( electrocytes ) regenerate after amputation of the tail. Sternarchus spinal cords which have regenerated for 1 or more years show a progression in number of perikarya of electromotor neurons along the rostro-caudal axis. The most recently regenerated region of the cord is at the caudal end, which consists of a tube of ependyma. Progressing rostrally along regenerated spinal cord from the caudal end, numerous cells are generated and large numbers of electromotor neurons differentiate. The maximum number of electromotor neurons per transverse section of regenerated cord is five times higher than in normal mature cord. Rostral to this, the number of electromotor neurons decreases gradually to the normal number near the transition zone (the border with unregenerated cord). As the more rostral regenerated cord has presumably had a longer period of regeneration, we conclude that excess numbers of electromotor neurons are generated initially, and that subsequently the number of these neurons is decreased by cell death. This conclusion is supported by the fact that younger regenerates (2-4 months) have larger-than-normal numbers of perikarya of electromotor neurons extending up to the transition zone (Anderson and Waxman , 1981). No evidence of migration or depletion of electromotor neurons from unregenerated cord rostral to the amputation has been observed. Since the axons of the electromotor neurons in Sternarchus do not normally form any synapses, this study provides evidence that factors other than synaptic competition must be responsible for determining cell death during regeneration of these spinal neurons.

Animals↗
PubMed1984

Seasonal changes in white and brown adipose tissues in Clethrionomys gapperi (red-backed vole) and in Microtus pennsylvanicus (meadow vole).

Mass and gross composition of white and brown adipose tissues and of skeletal muscle were determined for C. gapperi and for M. pennsylvanicus from monthly samples of a 1-year period. Amounts of brown fat increased throughout autumn to a maximum in late winter and then declined to a minimum in the spring. Gross composition remained relatively constant throughout the year. Changes in white fat showed a trend similar to changes in brown fat. Relatively low mean values for muscle mass during summer were due to a change in the age structure of the vole population.

Acclimatization↗
PubMed1984

An outbreak of erythema infectiosum associated with human parvovirus infection.

Erythema infectiosum (EI) or fifth disease is a mild, acute exanthematous disease, occurring mainly among children, for which a causative virus has long been sought. In May 1983 an outbreak of exanthematous illness was reported in a primary school in North London. Children attending the school were investigated by questionnaire and 162 (43.9%) reported an illness with the features of EI. In each of 36 cases investigated virologically the illness was associated with parvovirus infection. Moreover, pre-existing antibody to parvovirus was correlated with protection from EI in 16 of 17 close family contacts of cases. We propose therefore that EI is the common manifestation of infection with the human parvovirus.

Adult↗
PubMed1984

Extracellular matrix organization in developing muscle: correlation with acetylcholine receptor aggregates.

Monoclonal antibodies recognizing laminin, heparan sulfate proteoglycan, fibronectin, and two apparently novel connective tissue components have been used to examine the organization of extracellular matrix of skeletal muscle in vivo and in vitro. Four of the five monoclonal antibodies are described for the first time here. Immunocytochemical experiments with frozen-sectioned muscle demonstrated that both the heparan sulfate proteoglycan and laminin exhibited staining patterns identical to that expected for components of the basal lamina. In contrast, the remaining matrix constituents were detected in all regions of muscle connective tissue: the endomysium, perimysium, and epimysium. Embryonic muscle cells developing in culture elaborated an extracellular matrix, each antigen exhibiting a unique distribution. Of particular interest was the organization of extracellular matrix on myotubes: the build-up of matrix components was most apparent in plaques overlying clusters of an integral membrane protein, the acetylcholine receptor (AChR). The heparan sulfate proteoglycan was concentrated at virtually all AChR clusters and showed a remarkable level of congruence with receptor organization; laminin was detected at 70-95% of AChR clusters but often was not completely co-distributed with AChR within the cluster; fibronectin and the two other extracellular matrix antigens occurred at approximately 20, 8, and 2% of the AChR clusters, respectively, and showed little or no congruence with AChR. From observations on the distribution of extracellular matrix components in tissue cultured fibroblasts and myogenic cells, several ideas about the organization of extracellular matrix are suggested. (a) Congruence between AChR clusters and heparan sulfate proteoglycan suggests the existence of some linkage between the two molecules, possibly important for regulation of AChR distribution within the muscle membrane. (b) The qualitatively different patterns of extracellular matrix organization over myotubes and fibroblasts suggest that each of these cell types uses somewhat different means to regulate the assembly of extracellular matrix components within its domain. (c) The limited co-distribution of different components within the extracellular matrix in vitro and the selective immune precipitation of each antigen from conditioned medium suggest that each extracellular matrix component is secreted in a form that is not complexed with other matrix constituents.

Animals↗
PubMed1984

Acetylcholine receptor aggregation parallels the deposition of a basal lamina proteoglycan during development of the neuromuscular junction.

To determine the time course of synaptic differentiation, we made successive observations on identified, nerve-contacted muscle cells developing in culture. The cultures had either been stained with fluorescent alpha-bungarotoxin, or were maintained in the presence of a fluorescent monoclonal antibody. These probes are directed at acetylcholine receptors (AChR) and a basal lamina proteoglycan, substances that show nearly congruent surface organizations at the adult neuromuscular junction. In other experiments individual muscle cells developing in culture were selected at different stages of AChR accumulation and examined in the electron microscope after serial sectioning along the entire path of nerve-muscle contact. The results indicate that the nerve-induced formation of AChR aggregates and adjacent plaques of proteoglycan is closely coupled throughout early stages of synapse formation. Developing junctional accumulations of AChR and proteoglycan appeared and grew progressively, throughout a perineural zone that extended along the muscle surface for several micrometers on either side of the nerve process. Unlike junctional AChR accumulations, which disappeared within a day of denervation, both junctional and extrajunctional proteoglycan deposits were stable in size and morphology. Junctional proteoglycan deposits appeared to correspond to discrete ultrastructural plaques of basal lamina, which were initially separated by broad expanses of lamina-free muscle surface. The extent of this basal lamina, and a corresponding thickening of the postsynaptic membrane, also increased during the accumulation of AChR and proteoglycan along the path of nerve contact. Presynaptic differentiation of synaptic vesicle clusters became detectable at the developing neuromuscular junction only after the formation of postsynaptic plaques containing both AChR and proteoglycan. It is concluded that motor nerves induce a gradual formation and growth of AChR aggregates and stable basal lamina proteoglycan deposits on the muscle surface during development of the neuromuscular junction.

Animals↗
PubMed1984

Parvovirus infection in a family associated with aplastic crisis in an affected sibling pair with hereditary spherocytosis.

There have been many reports of aplastic crisis preceded by a febrile illness in hereditary haemolytic anaemias. Recent research has shown that the human parvovirus may be a causative agent. We report on an adult sibling pair with hereditary spherocytosis who presented in aplastic crisis after a febrile illness. Both had evidence of recent parvovirus infection, shown by the presence of IgM class specific antibody in their sera. The children of one of the sibling pair, one of whom has hereditary spherocytosis but no chronic haemolysis, showed similar evidence of acute parvovirus infection.

Adult↗
PubMed1984

Glial fibrillary acidic protein in regenerating teleost spinal cord.

Immunohistological and ultrastructural studies were carried out on normal and regenerating spinal cord of the gymnotid Sternarchus albifrons, and in the brain and spinal cord of the goldfish Carassius auratus, to examine the distribution of glial fibrillary acidic protein (GFAP) in these tissues. Sections of normal goldfish brain and spinal cord exhibited positive staining for GFAP. In normal Sternarchus spinal cord, electron microscopy has revealed filament-filled astrocytic processes; however, such astrocytic profiles were more numerous in regenerated cord. Likewise, while normal Sternarchus spinal cord showed only a small amount of GFAP staining, regenerated cords were strongly positive for GFAP. Positive staining with anti-GFAP was observed along the entire length of the regenerated cord in Sternarchus, and was especially strong in the transition zone between regenerated and unregenerated cord. Both regeneration of neurites and production of new neuronal cell bodies occur readily in such regenerating Sternarchus spinal cords (Anderson MJ, Waxman SG: J Hirnforsch 24: 371, 1983). These results demonstrate that the presence of GFAP and reactive astrocytes in Sternarchus spinal cord does not prevent neuronal regeneration in this species.

Animals↗
PubMed1984

Autoantibodies to platelet glycoprotein IIb/IIIa and to the acetylcholine receptor in a patient with chronic idiopathic thrombocytopenic purpura and myasthenia gravis.

The coexistence of chronic idiopathic thrombocytopenic purpura and myasthenia gravis has been infrequently reported. We report another case and show the coexistence of autoantibodies to the platelet glycoprotein IIb and IIIa complex and the acetylcholine receptor. Autoantibody levels were followed during 8 weeks of treatment with cyclophosphamide, vincristine, and prednisone; the concentration of both autoantibodies fell during treatment but without measureable clinical improvement.

Adult↗