PubMed Health⌕ Search

Biomedical subjects

J M Levine

Publications and source records attributed to J M Levine.

At least 19 recordsLinked to original sources
PubMed1992

Modulation of a Ca2+ signaling pathway by GM1 ganglioside in PC12 cells.

The effects of exogenous GM1 ganglioside on depolarization and ligand-induced Ca2+ signaling were investigated in PC12 cells. Cellular responses to K+ depolarization and bradykinin application in control and GM1-treated cells were examined with respect to: 1) changes in the intracellular Ca2+ concentration ([Ca2+]i) measured using fura-2 fluorescence in single cells, and 2) changes in Ca(2+)-dependent protein kinase activity as assayed by two-dimensional phosphopeptide analysis of the site-specific phosphorylation of tyrosine hydroxylase. Pretreatment of cells with GM1 (10 or 100 microM) enhanced K+ depolarization-stimulated increases in [Ca2+]i and in 32PO4 incorporation into tyrosine hydroxylase phosphopeptide T2, a Ca2+/calmodulin-dependent protein kinase II substrate. In contrast, GM1 treatment had no effect on the transient increases in [Ca2+]i evoked by bradykinin or on bradykinin-induced increases in the site-specific phosphorylation of tyrosine hydroxylase. The depolarization-induced and GM1-enhanced increases in [Ca2+]i and T2 phosphorylation were prevented by removal of external Ca2+ or pretreatment with 1 microM nitrendipine, suggesting that these increases result from Ca2+ entry through dihydropyridine-sensitive Ca2+ channels. The ability of exogenous gangliosides to potentiate increases in [Ca2+]i may underlie their diverse neuritogenic and neurotrophic actions in the nervous system.

Animals↗
PubMed1992

Historical perspective: the neurotrophic theory of skin ulceration.

Though nearly forgotten, the neurotrophic theory was very much a part of mainstream medical thinking during the mid-nineteenth century. This theory stated that all bodily organs are maintained by special nutritional factors secreted by the central nervous system. Development of skin ulceration in the face of neurologic injury became a model for the theory, and controversy involved two great neurologists of the time, Jean Martin Charcot and Edouard Brown-Séquard. As the neurotrophic theory fell into disfavor, interest in decubitus ulcers waned as well. Today, pressure sores remain a major epidemiologic problem for the growing population of frail elderly persons in both acute and long-term care settings. Because of the increased mortality, morbidity, and cost associated with these lesions, attention needs to be refocused on research and education concerning the decubitus ulcer.

Animals↗
PubMed1992

Historical notes on pressure ulcers: the cure of Ambrose Paré.

Ambrose Paré practiced surgery in 16th century France, and is considered a founding father of modern medical surgical practice. History books remember him mainly for innovations in treating war wounds, but few are aware of his treatment for skin ulcers. His textbooks contain instructions sounding quite similar to ours, including nutrition, pain relief, and debridement. Paré's autobiography relates the case of a wounded French aristocrat who developed a pressure ulcer and was successfully cured.

France↗
PubMed1991

Stimulation of a Ca(2+)-dependent protein kinase by GM1 ganglioside in nerve growth factor-treated PC12 cells.

We have investigated the ability of exogenous gangliosides to modulate nerve growth factor (NGF) signal transduction in PC12 cells. The effects of exogenous ganglioside GM1 on multiple protein kinase activities were assayed by analyzing site-specific serine phosphorylation of tyrosine hydroxylase (TyrOHase) by two-dimensional phosphopeptide mapping. In the presence of NGF, exogenous GM1 (1-10 microM) increased 32P incorporation into TyrOHase phosphopeptide T2, a Ca2+/calmodulin-dependent protein kinase substrate whose phosphorylation is not normally affected by NGF treatment. In the absence of NGF, GM1 treatment had no significant effects on TyrOHase phosphorylation. The removal of extracellular Ca2+ or blockade of dihydropyridine-sensitive Ca2+ channels prevented the GM1-induced increases in 32P incorporation into phosphopeptide T2. Exogenous GM1 also potentiated K+ depolarization-induced increases in the phosphorylation of TryOHase. These results suggest that the stimulatory effects of exogenous GM1 ganglioside on NGF actions may be due to its ability to potentiate a Ca(2+)-dependent signaling pathway.

Adrenal Gland Neoplasms↗
PubMed1990

Type II glucocorticoid receptors are expressed in oligodendrocytes and astrocytes.

Glucocorticoid hormones affect gene expression directly at the level of transcription via intracellular receptors that translocate to the nucleus in the presence of steroid. In the brain, two types of high-affinity receptors bind glucocorticoids, the type I, mineralocorticoid receptor and the type II, glucocorticoid receptor (GR). Both receptor types are expressed by many types of neurons. Although binding studies have suggested that glial cells may also express receptors, the expression of these receptors in specific classes of glia has not been studied previously. This immunocytochemical study was undertaken to determine which of the different classes of glial cells express type II GR. Primary cultures of mixed glial cells from rat cerebrum and cerebellum, purified oligodendrocytes and astrocytes, as well as two glial tumor cell lines were screened for the expression of glucocorticoid receptors using a mouse monoclonal antibody directed against rat liver GR (BuGR-2). Glial cell types were identified by morphology and immunoreactivity (IR) with antibodies directed against glial fibrillary acidic protein (GFAP), cyclic nucleotide phosphodiesterase (CNP), or myelin basic protein (MBP). Double immunofluorescence microscopy revealed that all GFAP-IR cells (type 1 and type 2 astrocytes), all CNP- or MBP-IR cells (oligodendrocytes), as well as immature and intermediate cell types expressed GR, although at different levels. C6 glioma and JScl1 Schwannoma cells were observed to express moderate to high levels of GR. Furthermore, cells grown in the absence of glucocorticoids had diffuse GR staining over the cytoplasm, whereas cells grown in the presence of the synthetic glucocorticoid dexamethasone had strong nuclear staining. These results demonstrate that, in vitro, all classes of glial cells express glucocorticoid receptors that can translocate to the nucleus in the presence of hormone. These observations suggest that glial cells are major targets for glucocorticoid-directed control of gene transcription in the nervous system.

Astrocytes↗
PubMed1990

Lectin binding identifies a subpopulation of neurons in chick dorsal root ganglia.

We screened a variety of lectins with different sugar specificates to determine whether subpopulations of dorsal root ganglion (DRG) neurons in the chick can be distinguished by the carbohydrates they express. Of the 15 lectins tested only those that recognize N-acetylgalactosamine (galNac) residues labeled a subset of DRG neurons. For example, Dolichos biflorus (DBA) labeled a population of small-diameter neurons in the dorsomedial DRG and their terminals in the dorsal horn in hatchling chicks. Staining of live neurons in vitro demonstrated that DBA was binding to the cell surface. Labeling first appeared in sensory neurons at about St.38 (E12) and in dorsal horn laminae 1 and 2 at about St.42 (E16). Fainter labeling appeared somewhat later in lamina 3, after hatching. Labeling of the tissue sections was eliminated by chloroform: methanol extraction and reduced by alpha-N-acetylgalactosaminidase digestion, but survived trypsinization. Together these results suggest that a subset of DRG neurons in the chick can be identified by the presence of a cell surface glycoconjugate, perhaps a glycolipid, containing terminal alpha-linked galNac residues.

Acetylgalactosamine↗
PubMed1990

Leg ulcers: differential diagnosis in the elderly.

Leg ulcers are a common problem encountered in the elderly. Because their origins are often multifactorial, it is essential for the primary care physician to have a sound knowledge of differential diagnosis to institute proper treatment. This review discusses salient historical points as well as bedside physical examination techniques useful in patients presenting with leg ulcer. Also discussed are pathophysiology of most common types of ulcer, including venous disease, arterial disease, diabetes, and physical agents. Less common causes of leg ulcer are also reviewed.

Aged↗
PubMed1989

Neuronal influences on glial progenitor cell development.

The role of cell-cell interactions in the development of bipotential glial progenitor cells in cultures of rat cerebellum and optic nerve was studied. In the cerebellar cultures, progenitor cells divide slowly and most of their progeny develop into additional progenitor cells. Progenitor cells isolated from postconfluent cultures of cerebellum, however, develop rapidly into oligodendrocytes when grown in a serum-free medium. Factors secreted or shed into the medium by young cerebellar interneurons stimulate optic nerve progenitor cells to divide and promote the survival of progenitor cells. These factors appear to alter the function of the internal clock that regulates the timing of oligodendrocyte differentiation. These results suggest that the neuronal microenvironment can influence the lineage decisions of multipotential glial progenitor cells.

Animals↗
PubMed1989

Pressure sores: a plan for primary care prevention.

Pressure sores are a preventable cause of increased morbidity, mortality, and treatment cost. Prevention begins with a knowledge of risk factors, both external and internal, and specific interventional measures for each. Management is best implemented using a team: the physician, nurse, nurse's aide, rehab nurse, physical therapist, dietitian, and occupational therapist, with an informed physician as team director. New management tools available include risk factor assessment scales to help in targeting resources.

Aged↗
PubMed1989

Atypical locations of pressure sores: presentation of two cases.

When we consider pressure sores, we usually think of their location in areas of contact with the bed or chair. However, in the presence of risk factors, any area of skin is subject to breakdown if exposed to constant pressure. This article presents two cases demonstrating unusual locations of pressure sores, and discusses underlying risk factors which contributed to their genesis. Vigilant attention to risk factor intervention by the multidisciplinary care team can prevent the incidence of this common complication of immobility. The use of a standardized risk factor assessment scale can be a useful guide to prevention planning.

Aged↗
PubMed1987

Light and electron microscopic localization of a cell surface antigen (NG2) in the rat cerebellum: association with smooth protoplasmic astrocytes.

Immunofluorescence and immunoperoxidase techniques were used to localize a cell surface chondroitin-sulfate proteoglycan antigen, termed NG2, in the developing and adult rat cerebellum. In the adult, both polyclonal and monoclonal anti-NG2 antibodies labeled cells throughout the cerebellar cortex, with the labeled cells being especially prominent in the molecular layer. The labeled cells had small, irregularly shaped cell bodies from which thin highly branched processes radiated in a stellate array. The NG2-labeled cells were not labeled with antibodies against glial fibrillary acidic protein (GFAP), vimentin, or S-100 protein, intracellular markers for astrocytes. However, electron microscopic immunocytochemical analysis of NG2 immunoreactive cells revealed a cell morphology consistent with that of protoplasmic astrocytes. Labeled cell bodies contained a thin rim of organelle-poor cytoplasm surrounding a euchromatic nucleus. Thick processes originating from the cell soma tapered to form thin branches with highly irregular surface contours that extended between adjacent neuronal elements. The labeled processes did not form synapses in the neuropil, and no synaptic profiles onto anti-NG2-labeled cell bodies or processes were observed. Thus, we conclude that the NG2 antigen is a cell surface marker for a class of smooth protoplasmic astrocytes. Immunoreactive cells were seen in the developing cerebellum beginning at embryonic day 16. The number of labeled cells increased during the early stages of cerebellar development, reaching a peak at about postnatal day (PND) 4 or 5 and declining thereafter. In the developing cerebellum, labeled cells lying within the forming molecular layer resembled the cells seen in the adult, whereas cells lying deeper within the folia had an immature appearance with fewer processes and less branching. This apparent gradient of morphological maturation suggests that an interaction with parallel fibers in the developing molecular layer may play a role in the terminal cytodifferentiation of the NG2-labeled smooth protoplasmic astrocytes.

Animals↗
PubMed1987

Plasticity of developing cerebellar cells in vitro studied with antibodies against the NG2 antigen.

The NG2 antigen, a chondroitin-sulfate proteoglycan, is a cell surface marker for a class of smooth protoplasmic astrocytes found throughout the brain and at high frequency in the cerebellar molecular layer (Levine and Card, 1987). To study the development of the cerebellar astrocytes at the level of the single cell, we have analyzed the distribution of the NG2 antigen by indirect immunofluorescence in dissociated cell cultures prepared from postnatal cerebella and compared that distribution to the distribution of several other cell surface and intracellular antigens that identify specific cell types in cultures of nervous tissue. When cerebellar cells from 5 d rat pups were grown in a medium containing 10% fetal calf serum, the NG2-labeled cells, which constituted 0.1-1.0% of the total glial cells present, contained glial fibrillary acidic protein (GFAP)-immunoreactive filaments and bound monoclonal antibody A2B5, a surface marker for neurons and some astrocytes. Approximately 30% of the NG2-labeled cells were also labeled with tetanus toxin, an additional surface marker for neurons and immature astrocytes. Less than 2% of the cells were labeled with antibodies against galactocerebroside or with monoclonal antibody O1, both of which are surface markers for oligodendrocytes. About half the NG2-labeled cells exhibited high-affinity uptake of 3H-GABA, and this uptake was partially inhibited by both beta-alanine and DABA. Thus, the NG2 antigen is a cell surface marker for a subpopulation of the type II or fibrous astrocytes present in the cultures. When the cerebellar cells were grown in a chemically defined, serum-free medium, the NG2-labeled cells had a stellate morphology and between 50-60% of the cells bound tetanus toxin. Although almost all the cells bound antibody A2B5, less than 5% of the cells expressed either of the oligodendrocyte surface markers or GFAP immunoreactivity. As was the case with cells grown in serum-containing medium, 60% of the NG2-labeled cells had high-affinity uptake of 3H-GABA. However, this uptake was inhibited by DABA but not by beta-alanine. This phenotype may be the in vitro analog of the NG2-labeled, filament-lacking, smooth protoplasmic astrocytes identified in the intact adult cerebellum. The expression of these 2 phenotypes could be reversed by switching the tissue culture medium within 5 d of plating the cells. These results demonstrate that the in vitro environment can influence the phenotypic properties expressed by developing cerebellar astrocytes and suggest that smooth protoplasmic astrocytes may be developmentally related to glial cells of the O-2A lineage.

Animals↗
PubMed1987

Characteristics of preschool children diagnosed as having an atypical pervasive developmental disorder.

Pediatricians and child psychiatrists encounter preschool children who are not autistic, but who have early deficits in both interpersonal and communication skills. Confusion exists over their diagnosis. Eighteen atypical children currently diagnosed as having an atypical pervasive developmental disorder are described. Areas discussed are social relatedness, speech and language, mental status, cognition, behavior, perception, social background, and medical/neurological status. These children constitute a distinct and frequently seen group within the spectrum of pervasive developmental disorders. Their characteristics are not currently captured within a diagnostic category in the Diagnostic and Statistical Manual, Third Edition (DSM-III), of the American Psychiatric Association. A revision of DSM-III, DSM-III-R, is currently being prepared. These children may not be captured within a diagnostic category in DSM-III-R. The distinguishing characteristics are onset before the age of three, language delay with disordered communication, social relationships characterized by variable relatedness, ritualistic or manneristic behaviors, the likelihood of hyperactivity and/or a short attention span, affective disturbances, excessive anxiety, and a thinking disorder or perseverative behaviors.

Affect↗
PubMed1986

Induction of altered c-src product during neural differentiation of embryonal carcinoma cells.

The expression of the cellular src gene product pp60c-src was examined in an embryonal carcinoma cell line that differentiates in vitro into neuronlike cells after being treated with retinoic acid. Quantitative and qualitative changes in c-src expression accompanied the events associated with neuronal differentiation. The levels of pp60c-src increased 8- to 20-fold during the period when the cells elaborated neuritic processes and expressed neuron-specific proteins. The electrophoretic mobility of pp60c-src induced in these cells was retarded in comparison with that in untreated cells or in treated cells before neurite elaboration. The shift in electrophoretic mobility was due to an alteration in the amino terminal 16,000 daltons of pp60c-src and similar to an alteration of c-src protein found in neural tissues and in pure primary cultures of neuronal cells. These results indicate that expression of pp60c-src induced by retinoic acid in these embryonal carcinoma cells mimics the expression of c-src in developing neurons. Therefore, this embryonal carcinoma cell line provides a model system to investigate the function of the src protein in neuronal differentiation.

Cell Differentiation↗
PubMed1986

Localization of a neurectoderm-associated cell surface antigen in the developing and adult rat.

The distribution of a neurectoderm-associated carbohydrate antigen (termed D1.1) in tissues of the developing and adult rat was determined using indirect immunofluorescent techniques. The antigen was detected as early as embryonic days 8 and 9 when it was localized to cells within the developing neural plate and neural tube. As the central nervous system (CNS) developed, the anti-D1.1 antibody labeled neuroepithelial cells but not terminally differentiated neurons or glial cells. In addition, the notochord and somatic mesoderm were labeled transiently with the antibody. Outside of the CNS, the antibody labeled dorsal root ganglia neurons, adrenal chromaffin cells and cells of the kidney glomerulus. These tissues were labeled at embryonic day 14 and the labeling persisted in the adult. We used a sensitive immunoautoradiography assay to identify antigenic gangliosides present in extracts of these tissues. The anti-D1.1 antibody recognized a ganglioside of kidney and adrenal glands that has a chromatographic mobility identical to that of the D1.1 antigen previously identified from cell lines and developing cerebellum. However, the antibody bound to a separate and distinct set of gangliosides present in extracts of adult dorsal root ganglia. Thus, the carbohydrate sequence recognized by the antibody can be associated with more than one molecular species of ganglioside. These results demonstrate that within the context of the developing CNS, the D1.1 antigen is a stage-specific embryonic antigen, but, as is the case with other cell surface carbohydrate antigens, is also found on a limited but developmentally unrelated set of tissues in the adult.

Animals↗
PubMed1986

Cell surface changes accompanying the neural differentiation of an embryonal carcinoma cell line.

The murine embryonal carcinoma cell line P19S18O1A1 develops into neuronlike cells after treatment with retinoic acid (Edwards and McBurney, 1983). We have analyzed the expression of cell surface carbohydrate antigens and intracellular cytoskeletal antigens in differentiating O1A1 cells in order to identify the cell types present in the cultures and to characterize the differentiation process. Undifferentiated O1A1 cells express the SSEA-1 antigen, GD3 ganglioside, and the D1.1 ganglioside antigen, carbohydrate markers that are found on early embryonic cells and neuroepithelial germinal cells in vivo. The cells also bind tetanus toxin, cholera toxin, and monoclonal antibody A2B5, probes that bind to gangliosides found on the surfaces of neurons and immature astrocytes in vivo and in vitro. They contain vimentin-type intermediate filament antigens but have no detectable neurofilament or glial filament protein antigens. After aggregation of the cells in medium containing retinoic acid followed by growth in a serum-free chemically defined medium, over 80% of the cells differentiate into neurons as determined by immunofluorescent labeling with antibodies against neurofilament protein antigens. The differentiated cells no longer express either the embryonic or neuroepithelial carbohydrate antigens, but they continue to express the cell surface markers characteristic of neurons. These changes in the expression of cell surface antigens are accompanied by changes in ganglioside metabolism, including a shift towards the synthesis of more complex gangliosides. Thus, the retinoic acid-induced changes in O1A1 cells in vitro resemble the in vivo development of neurons. This establishes the O1A1 cell line as a relevant model system for studies of the molecular basis of neuronal differentiation and development.

Antibodies, Monoclonal↗
PubMed1985

Antibody against nerve growth factor-inducible large external (NILE) glycoprotein labels nerve fiber tracts in the developing rat nervous system.

The NILE (nerve growth factor-inducible large external) glycoprotein is a 230,000-dalton molecule found on the surface of PC12 cells. Immunologically cross-reactive glycoproteins in the molecular weight range of 215,000 to 230,000 have been found on many types of neurons in culture. Using immunohistochemical methods, we have shown that NILE-related glycoproteins are present in neuronal fiber tracts of the developing rat brain. Antibody against the NILE glycoprotein specifically labels processes that appear identical to those recognized by antibodies against the neurofilament triplet of proteins. These processes are clearly distinct from the radial glial fibers recognized by antibody against the intermediate filament protein vimentin. NILE glycoprotein is not distributed uniformly over the entire neuronal surface but is concentrated on neurites and is much less abundant on cell bodies. NILE-positive fiber tracts are first seen in the spinal cord and rhombencephalon on embryonic day 11 and over the next 2 days appear in the mesencephalon and diencephalon. Staining in the telencephalon is not seen until embryonic day 15. The appearance of NILE immunoreactivity in these various regions closely parallels the appearance of neurofilament polypeptides, suggesting that NILE-related glycoproteins are present during the early phases of fiber tract formation. This idea is supported by the finding that the NILE glycoprotein can be found postnatally in parts of the nervous-system such as the cerebellar cortex and olfactory bulb which undergo major histogenesis during the postnatal period. In the cerebellum the appearance of NILE immunoreactivity in the two major fiber zones, the molecular layer and the white matter, parallels the development of the fiber structure of these layers. These findings support tissue culture studies which suggest a role for the NILE glycoprotein in mediating nerve fiber fasciculation.

Animals↗