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Biomedical subjects

M B Bornstein

Publications and source records attributed to M B Bornstein.

At least 37 records · Page 2Linked to original sources
PubMed1985

Measles virus matrix protein synthesized in a subacute sclerosing panencephalitis cell line.

Measles virus generally produces acute illness. Rarely, however, persistent infection of brain cells occurs, resulting in a chronic and fatal neurological disease, subacute sclerosing panencephalitis (SSPE). Evidence indicates that expression of the measles virus matrix protein is selectively restricted in this persistent infection, but the mechanism underlying this restriction has not been identified. Defective translation of matrix messenger RNA has been described in one SSPE cell line. This report presents evidence that in a different SSPE tissue culture cell line IP-3-Ca, the matrix protein is synthesized but fails to accumulate. A general scheme is proposed to reconcile the different levels at which restriction of matrix protein has been observed.

Cell Line↗
PubMed1985

Effect of insulin, proinsulin and pancreatic extract on myelination and remyelination in organotypic nerve tissue in culture.

The effect of insulin, proinsulin and crude pancreatic extract was studied in organotypic nerve tissue cultures, principally in relation to the development of myelin. Cultures were exposed to media supplemented with these substances beginning on the first day of explantation. By 4 days in vitro, there was a good neuritic outgrowth from all the fragments. That from the insulin and pancreatic extract-fed were more profuse and extended further than from the control group. By 8-12 days in vitro it was also possible to observe more myelinated axons in these treated groups. The pattern of changes in the myelin associated enzyme activity, 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) paralleled the differential increase in myelination. Insulin-fed cultures showed a more rapid increase in CNPase activity, which, after 21 days in vitro reached a plateau about 30-50% over that of the controls. Cultures treated with pancreatic extract showed a similar pattern of increased activity, while in proinsulin-treated explants the activity was only significantly higher after 21 days in vitro. To study the effect of these substances on remyelination, well myelinated cultures were completely demyelinated by exposure to anti-white matter antiserum and were subsequently exposed to the same normal control or supplemented media. The amount of myelin and concomitantly the CNPase activity increased rapidly and in the same proportion between the various groups as was observed previously during primary myelination. Insulin as well as crude pancreatic extract and, to some extent, proinsulin demonstrated a marked effect on the time of onset and principally on the total amount of myelin developed by treated cultures as compared to those maintained in normal nutrient medium.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗
PubMed1985

Fine structure of astrocytic processes during serum-induced demyelination in vitro.

Astrocytic changes were examined ultrastructurally during serum-induced demyelination in organotypic cultures of mouse spinal cord tissue. The myelin sheaths of most myelinated fibers showed myelin breakdown. Sheet-like astrocytic processes completely and closely surrounded the demyelinating fibers and frequently engulfed myelin fragments. These processes were virtually devoid of glial filaments or microtubules and contained flocculogranular material, round and elongated cisterns and glycogen granules. Penetration of the myelin sheath by astrocytic processes was only rarely found. The cell body of the astrocyte was never insinuated between the myelin sheath and the axon. No endocytosis of myelin droplets via coated pits on the surface of astrocytes was observed. In comparison with phagocytic mononuclear cells in vivo, astrocytes in vitro dispose of myelin debris less actively. Astrocytes in serum-induced demyelination probably play a nonspecific but fundamental role during degeneration in segregating damaged nerve fibers from surrounding neuronal elements.

Animals↗
PubMed1985

Basal lamina formation by astrocytes in organotypic cultures of mouse spinal cord tissue.

The relationship between astrocytes, basal lamina and mesenchymal tissue was analyzed ultrastructurally in myelinated organotypic cultures of mouse spinal cord tissue grown in combination with its pia-arachnoid membrane. A discontinuous, well-developed basal lamina covered flat astrocytic processes which formed the basal layer of the explant opposing the pia-arachnoid membrane. Some astrocytic processes on the surface facing the pia-arachnoid membrane lacked basal lamina, had an irregular surface with microvillus-like protrusions but within the explant they formed intercellular chambers which were surrounded by basal lamina. Even in the presence of mesenchymal tissue which appeared to facilitate the formation of basal lamina in this system, the absence of basal lamina on some areas of the astrocytic plasma membrane suggests regional differences of the astrocytic processes and might reflect the epithelial nature of the astrocyte.

Animals↗
PubMed1985

Correlation between 2',3'-cyclic nucleotide 3'-phosphohydrolase activity and demyelination in vitro using a syngeneic system.

Cultures of myelinated SJL/J fetal mouse spinal cord were incubated with serum and lymphoid cells from syngeneic animals with experimental allergic encephalomyelitis (EAE) induced by syngeneic spinal cord homogenate (SSCH) in complete Freund's adjuvant or others injected with complete Freund's adjuvant alone. After 24 or 48 h of exposure, demyelination was determined by light microscopic examination and quantification of 2',3'-cyclic nucleotide 3'-phosphohydrolase activity. Cultures exposed to spleen or lymph node cells from SSCH-sensitized animals showed the greatest alterations in myelin and decreases in 2',3'-cyclic nucleotide 3'-phosphohydrolase activity whereas serum from these animals had less effect. Cells and serum from complete Freund's adjuvant-injected control animals also induced structural changes in myelin that were significantly less than changes induced by cells and serum from animals with EAE. These experiments show that lymphoid cells and serum obtained from SJL/J mice with acute EAE affected myelin biochemistry and morphology in syngeneic CNS cultures.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗
PubMed1985

Preliminary analysis of cell and serum-induced demyelination in vitro using a syngeneic system.

Previous studies on immune-mediated demyelination in vitro have usually tested sera and lymphoid cells in heterologous systems. The present study involved the examination of CNS cultures of SJL/J mouse spinal cord exposed to sera and lymphoid cells isolated from animals of the same strain previously injected with syngeneic spinal cord homogenate (SSCH) to induce acute experimental autoimmune encephalomyelitis (EAE). Examination of treated versus control cultures by light and electron microscopy at varying time points after exposure showed that spleen cells from animals with EAE produced significant demyelination and oligodendroglial cell destruction. Lymph node cells and sera from the same animals showed the same type of demyelination without marked oligodendroglial cell damage. The degree of myelin damage induced by spleen cells and sera did not correlate with the clinical status of the animal but a slight positive correlation was noted with lymph node cells. Cells and sera from control animals did not induce significant demyelination. These results suggest that in this syngeneic mouse system, there was a differential effect among cells from spleens and lymph nodes, and serum. This syngeneic system might allow for more meaningful pathologic and genetic analyses of immune-mediated demyelination.

Animals↗
PubMed1985

Immunogenic potentials of copolymer I in normal human lymphocytes.

Copolymer I (COP I), a nonencephalitogenic polypeptide analogous to myelin basic protein, is currently being tested for possible effectiveness in treating MS. Peripheral blood mononuclear cells from normal human donors respond blastogenically to the L-form of COP I. This response was greater than that obtained with either bovine or guinea pig myelin basic protein (GPMBP), with no specificity for a particular T-cell subset. Analyses of culture supernatants demonstrated the presence of interleukin-2 and gamma interferon. Mononuclear cells from human fetal cord blood also responded blastogenically to COP I, but the magnitude of the response did not differ from that induced by GPMBP.

Animals↗
PubMed1984

Quantitative chemical analysis of demyelination in cultured mouse spinal cord.

These studies were designed to determine whether chemical parameters can be used to quantify the demyelinative potency of anti-CNS sera or other demyelinating factors as revealed by cultured nerve tissue. The activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) and the amount of some major myelin lipids were measured in cultured embryonic mouse spinal cord during different stages of demyelination. Cultures exposed to anti-white matter serum for various times (6-60 h) or various concentrations (2.5-25%) showed a decrease (up to -70%) in CNPase activity. This change paralleled the degree of demyelination as evaluated by light microscopic examination. Cultures exposed to normal rabbit serum under the same conditions did not show changes in the amount of myelin or in the activity of CNPase. Conversely, changes in the lipid content did not correlate with the morphologic evaluation of demyelination. Glycolipids were found to decrease in cultures exposed to anti-white matter as well as in those exposed to normal rabbit sera. The decrease in cerebrosides was higher with anti-white matter serum than with normal serum, but sulfatides were altered in similar amounts in both groups. In contrast, under the same conditions, the amount of total protein or other lipid such as total cholesterol is not altered. Therefore, biochemical analysis of some myelin components could constitute a more sensitive and reliable quantitative method for early evaluation of the time course of demyelination in cultured nerve tissues.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1984

The evolution of cellular degeneration in dorsal root ganglia exposed to doxorubicin in tissue culture.

Doxorubicin (Adriamycin) is a drug having both antibiotic and antimitotic properties. It intercalates between base pairs of DNA causing breaks in the helical strands. It is widely used as a cancer chemotherapeutic agent but is limited in use by a dose-related cardiomyopathy and necrosis of peripheral ganglia. This study of cultured mouse spinal cord and dorsal root ganglia examined the sequential pathological changes of living tissue by light and fluorescence microscopy and of fixed tissue by electron microscopy. Fluorescence microscopy showed that doxorubicin has rapid access to ganglia cells and preferentially binds to the nucleus and nucleolus. Pathological changes of the peripheral neurons include clumping of nuclear chromatin, relocation of the indented nucleus to an eccentric position, occasional loss of the nuclear envelope, dissociation of the nucleolus into the pars granulosa and the pars fibrosa, accumulation of inclusion bodies in the cytoplasm, swollen cisternae and a loss of Nissl substance. Axons display changes in localization of organelles prior to undergoing proximal Wallerian-like degeneration. Schwann cells occasionally display clumped nuclear chromatin. Some satellite cells undergo necrosis. These findings are dose- and time-related and essentially duplicate those previously reported in animal studies. Thus, the in vitro model may provide a useful tool for ascertaining the sequence of events occurring in sensory neuronopathy.

Animals↗
PubMed1983

The twitcher mouse: myelinogenesis in organotypic culture.

Myelinogenesis was followed in organotypic cultures of the spinal cord of the neurological mutant mouse, the Twitcher. As a clinically, pathologically and biochemically equivalent model of Krabbe disease this mutant is an important tool for investigating the nervous system. Normal initiation and development of myelination was observed. At 35 days in vitro (DIV) the Twitcher cultures exhibited blisters attached to the intact myelin sheath and bubbling of myelin suggestive of myelin breakdown. Myelin degeneration progressed thereafter. The Twitcher spinal cord survived in culture for more than two months, a period much longer than the life span of affected mice. In order to correlate pathological and biochemical changes, the activity of UDP-galactose:ceramide galactosyltransferase was quantitated in normal and Twitcher cultures. In both the Twitcher and the control groups the galactosyltransferase activity rapidly increased up to 20-25 DIV and then declined. The galactosyltransferase activity of the Twitcher tended to be lower than the controls even during the early myelination period. At 35 DIV the activity in the Twitcher was definitely lower than the controls, and at 52 DIV it was nearly negligible. The galactosyltransferase activity therefore correlated well with the morphologically observed early normal myelination and subsequent myelin degeneration.

Animals↗
PubMed1983

Chemical analysis of organotypic cultures of mouse spinal cord in normal, demyelinative, and nondemyelinative conditions.

Several biochemical parameters were analyzed in cultured embryonic mouse spinal cord during various stages of normal myelinogenesis or demyelination. In cultures demyelinated by exposure to anti-whole CNS tissue serum plus complement, the activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase (EC 3.1.4.37) was decreased 70%, whereas in cultures that did not show morphological changes with complement-inactivated anti-CNS serum or anti-myelin basic protein serum, the activity was 30% lower than in control cultures. The lipid composition of these cultures was quantitated by means of high-performance thin-layer chromatography densitometry technique. Cultures with normal nutrient medium alone or with the addition of 5% normal rabbit serum plus 10% guinea pig serum had 30% of the total lipid content of that present in newborn mouse spinal cord of the corresponding age. There were, however, relatively more lysophospholipids, cholesterol esters, triglycerides, and free fatty acids and less phosphatidylethanolamine and galactolipids in cultures as compared with normal spinal cord. Explants demyelinated by exposure to anti-CNS serum plus complement demonstrated principally a 70% decrease in the content of galactolipids with respect to normal cultures. When complement was inactivated, total lipids increased 42% (with increases of 40-70% in individual lipids). Inclusion of anti-myelin basic protein serum plus complement in the medium produced no significant changes in the lipid composition of the cultures.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗
PubMed1983

Ultrastructural studies of the dying-back process. VI. Examination of nerve fibers undergoing giant axonal degeneration in organotypic culture.

Organotypic tissue cultures, composed of structurally and functionally coupled explants of mouse spinal cord, dorsal root ganglia, and striated muscle, have been used to create a model of the distal (dying-back) axonopathy found in animals and humans with aliphatic hexacarbon neuropathy. Mature explants were treated with 50-650 micrograms/ml of the following hexacarbons dissolved in nutrient fluid: n-hexane, 2-hexanol, 2,5-hexanediol, methyl n-butyl ketone, 5-hydroxy-2-hexanone, 2,5-hexanedione (all neurotoxic), or 2,4-hexanedione (a non-neurotoxic diketone). High concentrations (400-650 micrograms/ml) induced pancytotoxic damage and necrosis of tissue within days, while the lower doses (50-100 micrograms/ml) induced no pathological changes over a period of several weeks. Continuous exposure of explants to 245-325 micrograms/ml (2.8 mM) of the neurotoxic hexacarbons caused specific pathological changes to develop in distal nerve fibers after three to six weeks. Initial changes seen in distal, nonterminal regions of myelinated fibers included: nodal elongation, axonal swellings on proximal-side paranodes, and paranodal myelin retraction. Prolonged treatment was associated with Wallerian-like degeneration of distal nerve fibers. Denuded paranodal swellings in more proximal regions of affected myelinated fibers adopted a more-normal size and underwent remyelination; this occurred during and after the course of treatment. Remyelination by lateral extension from adjacent Schwann cells was documented in living and fixed tissue. The observations confirm the spatial-temporal evolution of hexacarbon distal axonopathy previously suggested from comparable studies in vivo.

Animals↗
PubMed1982

Multiple sclerosis: trial of a synthetic polypeptide.

A synthetic polypeptide, copolymer I (COP I), composed of alanine, glutamic acid, lysine, and tyrosine, has been demonstrated to be nonencephalitogenic and nontoxic in laboratory animals, yet it is capable of suppressing experimental allergic encephalomyelitis. A preliminary open trial examined the ability of COP I to alter the course of disease in 12 patients with chronic progressive and 4 with exacerbating-remitting multiple sclerosis (MS). After therapy for as long as two years or more, no undesirable side reaction was noted in any patient. Three patients with chronic progressive MS and 2 with exacerbating-remitting disease are better. These results, which may represent simply a placebo effect or may be a significant response, are now being examined in randomized, placebo-controlled, double-blind pilot trials.

Adult↗
PubMed1982

Myelination in organotypic cultures of sympathetic ganglia.

Explants of mouse superior cervical ganglion (SCG), co-cultured with dorsal spinal cord, were grown for up to 4 weeks in vitro. In such cultures, scattered internodes of peripheral nervous system (PNS) myelin were observed, apparently associated with SCG neurites. Although rare, the incidence of PNS myelination in this system might merit further experimentation to provide a model facilitating the evaluation of postganglionic sympathetic myelination, which in vivo may be both extensive and morphologically unusual.

Animals↗
PubMed1982

Buckthorn neuropathy in vitro : evidence for a primary neuronal effect.

The neuropathy produced by toxins isolated from the buckthorn shrub (Karwinskia humboldtiana) has previously been proposed as a model for primary PNS demyelination in vivo. These toxins have been suggested to act through a metabolic effect on the Schwann cell. The aim of the present study was to use myelinated organotypic cultures of nervous tissue to dissect further the pathologic effects of these compounds. Combination cultures of mouse spinal cord and dorsal root ganglia were exposed to buckthorn toxins T/496 or T/544 at doses of 1-5 microgram/ml for periods of 48 hours (h) to 14 days. Ultrastructural findings from toxin-treated cultures indicated a primary effect upon the PNS axon, both myelinated and unmyelinated. The effect was expressed mainly as a widening of the periaxonal space, and also as a redistribution of most axonal organelles to a marginal position within the axon or to their close association with stacks of smooth endoplasmic reticulum, leaving more central regions occupied largely by neurofilaments. These changes were followed by focal axonal swelling, floccular disruption of the axoplasm and, ultimately, Wallerian degeneration. Myelin degeneration and chromatolytic changes in ganglion cell bodies appeared to be secondary to axonal alterations. This tissue culture model reproduces many of the features of buckthorn intoxication in vivo. However, the present results suggest that the toxic effect is primarily upon the axon rather than the Schwann cell, and would appear to be consistent with an abnormality in axoplasmic transport.

Animals↗