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Biomedical subjects

E L Hogan

Publications and source records attributed to E L Hogan.

At least 127 records · Page 7Linked to original sources
PubMed1984

Myelin basic protein gene expression in quaking, jimpy, and myelin synthesis-deficient mice.

Jimpy (jp), myelin synthesis-deficient (jpmsd), and quaking (qk) are mutations which affect myelination to different degrees in the mouse central nervous system (CNS). Total messenger RNA (mRNA) and myelin basic protein (MBP)-specific mRNA from brains of these three mutants have been analyzed by in vitro translation and immunoprecipitation with antibody to MBP. The results indicate that the three mutations do not affect the level of total MBP-specific mRNA in the CNS but do affect the relative proportions of the various MBP-related translation products encoded in vitro. In each case the proportions of 14K and 12K Mr MBP-related translation products are reduced and the proportions of 21.5K, 18.5K, and 17K Mr MBP-related translation products are increased relative to wild type. This effect is most pronounced in jp, less so in jpmsd, and least pronounced in qk animals. The MBP-related polypeptides that accumulate in vivo have also been analyzed in the three mutants by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting with antibody to MBP. The levels of all the major MBP-related polypeptides that accumulate in vivo are reduced in all three mutations. The reduction is most pronounced in jp, less in jpmsd, and least pronounced in qk animals. These results indicate that the jp, jpmsd, and qk mutations exhibit qualitatively similar phenotypic effects on MBP gene expression but the magnitude of the effect is proportional to the extent of hypomyelination in each mutant.

Animals↗
PubMed1984

Changes in myelin and axonal proteins in CaCl2-induced myelopathy in rat spinal cord.

Calcium-induced myelopathy was produced in rats by dripping 1.0 ml of a 10% solution of CaCl2 at pH 7.4 upon exposed spinal cord. Changes in spinal cord proteins were examined following application of calcium. Analysis of proteins by SDS-PAGE revealed progressive losses of neurofilament, microtubular, and glial filament proteins over a period of 8 hours to 5 days. Large losses of myelin proteins were also evident. The protein alterations observed correlate well with ultrastructural changes and resemble those previously found with physical trauma. These observations indicate that Ca2+ plays a pivotal role, possibly by activating proteinase(s), in the degeneration of axons and myelin sheath in both Ca2+-induced myelopathy and spinal cord injury.

Animals↗
PubMed1984

Orthostatic hypotension with brainstem tumors.

Three patients with brainstem tumors had orthostatic hypotension as the major presenting manifestation. Two patients had primary tumors that involved the dorsal medulla, pons, and rostral spinal cord; one was a malignant astrocytoma and the other a hemangioblastoma. The third patient had an oat cell carcinoma of the lung with subependymal spread to the medulla, pons, hypothalamus, and thalamus. Evaluation of baroreceptor function in the patient with the malignant astrocytoma showed a defect in the efferent sympathetic limb of the baroreceptor reflex arc.

Adolescent↗
PubMed1983

Novel pentahexosyl ganglioside of the globo series purified from chicken muscle.

A monosialosyl ganglioside, sialosylpentaglycosyl-ceramide, has been isolated from chicken pectoral muscle. This ganglioside is the first to be found which contains the glycosphingolipid structure of the globo series. It was extracted from tissue with a mixture of tetrahydrofuran and aqueous KCl and purified by anion exchange and silicic acid chromatography. Enzymic hydrolysis utilizing specific glycosidases and methylation technique were employed to establish the structure which is proposed to be: NeuAc alpha 2 leads to 3Gal beta 1 leads to 3GalNAc beta 1 leads to 3Gal alpha 1 leads to 4Gal beta 1 leads to 4GlcCer. The chain base was predominantly sphingosine and the fatty acids present were mainly stearate and oleate.

Animals↗
PubMed1983

High-performance liquid chromatographic resolution of p-nitrobenzyloxyamine derivatives of brain gangliosides.

A new quantitative procedure for the high-performance liquid chromatographic (HPLC) resolution of human brain gangliosides employing reversed-phase chromatography is described. To provide a derivative which can be determined by UV absorption techniques, p-nitrobenzyloxyamine was coupled to the gangliosides. Derivatization involves ozonation and cleavage of the ceramide double bond followed by oxime formation to the nascent aldehyde. Individual gangliosides, as they were resolved by HPLC, were collected. These fractions were then identified by thin-layer chromatography (TLC) and by gas chromatography of their monosaccharides. Quantitative results were obtained along with a marked increase in sensitivity over conventional resorcinol-hydrochloric acid quantitation of TLC-resolved gangliosides.

Brain Chemistry↗
PubMed1983

Purification of a calcium-activated neutral proteinase from bovine brain.

A calcium-activated neutral proteinase (CANP) resolved into three components has been partially purified from bovine brain. The method of isolation has resulted in 22,000, 7,100, and 8,000-fold purification for CANP I, II and III respectively. All three fractions require Ca2+ for activation. The characterization of the purified CANP I has shown that it is activated by 250 microM Ca2+ and the enzyme loses its activity when incubated in the presence of Ca2+ without substrate. Mg2+ is ineffective. The enzyme degrades neurofilament triplet proteins, tubulin and casein efficiently. The myelin basic protein is hydrolyzed after longer incubation. Bovine serum albumin and histones are unaffected. The enzyme is active at pH 5.5 to 9.0 with optimum between pH 7.5 and 8.5. It has a Km of 1.8 X 10(-7) M for the 69,000 dalton neurofilament protein. The enzyme is inhibited by sulphydryl blocking reagents and also by EGTA, leupeptin and E-64c. The SDS-PAGE analysis of the enzyme fractions has shown a major band at 66-68,000 daltons and two minor bands at 60,000 and 48-50,000 daltons for CANP I; a major band at 48-50,000 daltons and a minor band at 30-32,000 daltons for CANP II and a predominant doublet at 30-32,000 daltons with a minor band at 48-50,000 daltons for CANP III. The degradation of neurofilament proteins suggests that the CANP(s) may be involved in the turnover of these proteins.

Animals↗
PubMed1983

Protein composition of PNS myelin: developmental comparison of control and quaking mice.

Protein compositions were determined for sciatic nerve myelin isolated from young and adult control and quaking (Qk) mice. Age-related changes in the relative amounts of large (Pl) and small (Pr) basic proteins were found. In control animals, the ratio Pr/Pl increased with age, a change similar to that observed for the large (Bl) and small (Bs) CNS myelin basic proteins of adult mice. Pr/Pl also increased with age in the Qk mouse sciatic nerve, but only to the point that the value in the adult Qk mouse was similar to that observed for young control animals, a situation reminiscent of the effect of the Qk mutation on CNS basic proteins. Thus, our data suggest that the Qk mutation has a similar effect on peripheral nervous system (PNS) and CNS basic proteins. Our findings are consistent with recent electrophoretic and immunochemical data showing that PNS and CNS myelin basic proteins in rodents are analogous, and they suggest that the genetic program controlling basic protein expression is common to oligodendroglia and Schwann cells.

Aging↗
PubMed1983

Studies on subcellular fractions which are involved in myelin assembly: labeling of myelin proteins by a double radioisotope approach indicates developmental relationships.

The question of developmental relationships amongst myelin-related membranes in subfractions of myelinating mouse brain (15 days) was investigated by a time-staggered double isotope protocol using [3H]leucine and [14C]leucine. Preliminary results are interpreted and discussed in the context of a mathematical conceptualization of pulse-labeling kinetic analyses of myelin proteins in subcellular membrane compartments. Differences in ratio of the two leucine labels among proteins of myelin-containing subfractions are interpreted as confirming metabolic differences relating to various stages of development rather than precursor-product relationships. The incorporation into myelin of 14K, 17K, and 18.5K basic proteins (MBPs) occurs with relatively short delay times, following their synthesis (less than 5 min), and seems to occur simultaneously into all compartments. The 21.5K MBP and the proteolipid protein, on the other hand, require 10-14 min and 14-20 min, respectively. A scheme is presented to illustrate the probable assignment of subfractions to various myelin "compartments" during myelination, and to serve as a working hypothesis for studies on precursor-product relationships.

Animals↗
PubMed1982

Degradation of cytoskeletal proteins in experimental spinal cord injury.

Spinal cord injury was produced in rats by dropping a 10 g weight from 30 cm upon dura-invested exposed spinal cord. Examination of the fine structure of the traumatic lesion (15 min to 30 min) revealed granular degeneration of axons and occasional loosening of myelin lamellae. Older lesions (4 to 72 hours) showed degeneration of axons and vesiculation of myelin. At 15 minutes there is more loss of neurofilament proteins than of myelin proteins. Substantial decreases in the neurofilament and myelin proteins were observed at 30 minutes and the losses were even greater 2-72 hours after injury. This indicates that degeneration of axons may precede degradation of the myelin sheath and also that increased proteinase(s) activity, possibly activated by calcium, mediates the traumatic axonolysis and myelinolysis in experimental spinal cord trauma.

Animals↗
PubMed1982

Basic proteins of rodent peripheral nerve myelin: immunochemical identification of the 21.5K, 18.5K, 17K, 14K, and P2 proteins.

Proteins in peripheral nervous system and central nervous system myelin and homogenates of sciatic nerve and brain from young and adult mice and rats were characterized with affinity-purified anti-P2 and anti-myelin basic protein sera after electrophoretic transfer from sodium dodecyl sulfate-polyacrylamide gels to nitrocellulose sheets. Using this method we have identified a component of rodent peripheral nervous system myelin as P2 protein. Peripheral nervous system myelin also showed the presence of four basic proteins in addition to P2 protein. These were found to be analogous to the 14, 17, 18.5, and 21.5K species found in the central nervous system myelin. A number of high-molecular-weight proteins were also detected with anti-myelin basic protein serum in peripheral nervous system, as well as central nervous system myelin. In addition, we report the presence of a high-molecular-weight P2 cross-reactive protein in rodent brain stem homogenates, but not in central nervous system myelin. Key Words: Basic proteins--PNS myelin--CNS myelin--Immunocharacterization. Greenfield S. et al. Basic proteins of rodent peripheral nerve myelin: Immunochemical identification of the 21.5K, 18.5K, 17K, 14K, and P2 proteins.

Animals↗
PubMed1982

Abnormal regulation of IgG production in multiple sclerosis.

After stimulation with pokeweed mitogen (PWM), peripheral blood mononuclear cells (MNC) from patients with active multiple sclerosis (MS) produced significantly more IgG (8595 ng per milliliter, p less than 0.01) then MNC from normal age-matched controls (5477 ng per milliliter), whereas those tested during stable periods produced less IgG (4076 ng per milliliter, p less than 0.01). Treatment of MNC with sodium periodate (SP) generated suppressor cells for PWM-driven IgG production in normal controls and in most of the stable MS patients but in only 26% of those during active disease, in whom an increase in IgG production was often seen. This suggests a deficiency of inducible suppressor T cells associated with a supranormal B-cell response to polyclonal activation; T lymphocytes obtained from MS patients during active episodes strongly suppressed IgG production by normal B lymphocytes, whereas their B cells often produced more IgG in the presence of normal T cells. In active MS, a relative B-cell unresponsiveness to activated suppressor T cells would leave helper signals unbalanced, thus leading to increased B-cell activation, which might deplete the pool of inducible suppressor cells for IgG production.

B-Lymphocytes↗
PubMed1982

Familial myoadenylate deaminase deficiency and exertional myalgia.

In 14 members of four families with a hereditary syndrome of exertional myalgia, five of eight muscle biopsies from symptomatic individuals showed histochemical and biochemical absence of myoadenylate deaminase (MADA). In the others, MADA biochemical activity was normal in two and reduced but not absent (intermediate level) in one. Asymptomatic relatives had normal histochemical MADA activity, but three had intermediate biochemical levels. In a survey of 302 routine muscle biopsies, 3 of 36 patient with myalgia had absence of MADA. Three of 266 biopsied for other conditions were MADA-deficient. Despite some inconsistencies, MADA deficiency seems to be relevant to this clinical syndrome.

AMP Deaminase↗
PubMed1981

Ca2+-accumulation in experimental spinal cord trauma.

Quantitative measurements of the time course of calcium levels in experimental spinal cord trauma have been made. The injury was produced in rats by dropping a 10 g weight from 30 cm upon exposed dura-invested spinal cord. Lumbar sections of traumatized spinal cord and internal controls from remote cervical cord were excised and analyzed for calcium using atomic absorption spectroscopy. Total calcium levels in the lesioned cord were significantly elevated over control values within 45 min post-trauma (P less than 0.005), with maximal increase at 8 h. The increased levels of calcium in the lesion tissue confirm the previous morphologic finding of calcium deposits within axons in the lesion.

Animals↗
PubMed1980

Characterization of two gangliosides of the paragloboside series from chicken skeletal muscle.

Two glucosamine-containing gangliosides, a ceramide pentasaccharide and ceramide heptasaccharide, have been purified from the gangliosides of chicken skeletal muscle. The lipids were extracted with a mixture of tetrahydrofuran and aqueous KCl and purified by anion-exchange and silicic acid column chromatography. Their structures were determined by specific enzymatic hydrolysis and methylation analysis. The proposed structures are sialosyl derivates of: (a) paragloboside, and (b) paragloboside with an additional lactosamine disaccharide: (a) NeuAc alpha 2 leads to 3Gal beta 1 leads to 4GlcNAc beta 1 leads to 3Gal beta 1 leads to 4GlcCer, (b) NeuAc alpha 2 leads to 3Gal beta 1 leads to 4GlcNAc beta 1 leads to 3Gal beta 1 leads to 4GlcNAc beta 1 leads to 3Gal beta 1 leads to 4GlcCer. The long base was predominantly sphingosine and the acyl groups were mainly palmitate, stearate and oleate.

Animals↗
PubMed1980

Defective immunoregulation in multiple sclerosis.

Imbalances in T cell subpopulations have been reported in multiple sclerosis (MS). In the present study of 31 MS patients, the percentage of T cells with Fc receptors for IgG (Tg) was found to be increased in patients with chronic progressive disease, and another T cell subset binding to the Raji B lymphoid cell line was decreased. An inverse correlation (r = -0.675; < 95% confidence limit) was found between these two subsets, suggesting that they vary inversely in MS. The mitogenic responses of MS mononuclear cells, isolated T cells, and recombinet T and non-T cells to the lectins phytohemagglutinin and pokeweek mitogen (PWM) did not differ from those of normal cells. However, more immunoglobulin (Ig)-producing cells were generated in a PWM-driven system with cells from MS patients than with cells from age-matched controls (p < 0.05). Autologous recombination of separated T and non-T cells did not significantly modify these results. T cells from MS patients added to B cells from normal controls exerted an effect that was related to their percentage of Tg cells; that is, values above 15% were associated with a suppression of Ig production, whereas for Tg values below 12%, a helper effect or no modification was observed. These results suggest that changes in T cell subsets in MS are related to changes in functional ability to modulate Ig production by normal B cells. However, MS B cells partly escape regulation by their own T cells, suggesting an associated B cell hyperactivity.

Humans↗