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Biomedical subjects

B I Roots

Publications and source records attributed to B I Roots.

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

The effect of temperature- and oxygen-acclimation on phospholipids of goldfish (Carassius auratus L.) brain mitochondria.

Goldfish (Carassius auratus L.) were temperature- and oxygen-acclimated and the composition of the phospholipids and their acyl groups in brain mitochondria was determined. The proportion of ethanolamine to choline phospholipid was greater while the plasmenyl ethanolamine value (P-GPE/D- + P-GPE) was lower at the low acclimation temperature. For the ethanolamine glycerophospholipids, a rise in the ratio n-6/n-3 fatty acyl groups occurred with cold acclimation. No significant change in the ratio was exhibited by phosphatidyl choline. When the oxygen level was increased, at either acclimation temperature, a rise in the GPE/GPC ratio and the plasmenyl ethanolamine value resulted. The n-6/n-3 ratio was generally increased for the ethanolamine classes when the oxygen concentration was raised. The possible significance of these changes is discussed.

Acclimatization↗
PubMed1984

Immunoblot identification of 13.5 kilodalton myelin basic protein in goldfish brain myelin.

Myelin isolated from goldfish brain shows a multilamellar structure with a major dense line and two intraperiod lines. Sodium dodecyl sulfate gel electrophoresis revealed that the protein profile of goldfish brain myelin is distinctly different from that of rat brain myelin. No protein migrating to the position of proteolipid protein or DM-20 was seen in goldfish myelin. Goldfish acclimated to 5 degrees, 15 degrees, and 30 degrees C showed no qualitative differences in myelin proteins. The 13.5 kD protein in goldfish brain myelin and brain homogenate was intensely immunostained with the antiserum to human basic protein by the immunoblot technique. In contrast, none of the proteins of goldfish myelin were immunostained with antiproteolipid protein serum; however, both proteolipid protein and DM-20 of rat brain myelin were immunostained. The significance of the synthesis of myelin proteins by astrocytes in the goldfish brain is discussed.

Adaptation, Physiological↗
PubMed1983

Neurofilament accumulation induced in synapses by leupeptin.

The hypothesis that the usual absence of neurofilaments in synaptic terminals is due to their degradation by the calcium-activated protease present in axoplasm was tested by injecting leupeptin, which inhibits the protease, into the optic tectum of goldfish kept at 15 degrees and at 25 degrees C. The resulting accumulation of neurofilaments in synaptic terminals provides in vivo evidence in support of the hypothesis. The significance of these results and the potential uses of this pharmacological tool are discussed.

Animals↗
PubMed1983

Myelinating glia of earthworm giant axons: thermally induced intramembranous changes.

The median and lateral giant axons in the ventral nerve cord of the earthworm Lumbricus terrestris are ensheathed by extensive spiral glial cell wrappings which resemble vertebrate myelin. The other, smaller, axons are encompassed by attenuated glial processes, as is typical of invertebrates. The fine structural details of the glial cells have been studied in thin sections and in replicas produced by freeze-fracturing where the intramembranous particle (IMP) populations within the lipid bilayer are visible. These consist of both low-profile IMPs as well as prominent ones 6-8 nm in diameter, scattered at random over the lipid interface in the myelinating glia. The larger IMPs on both P and E faces number about 80/mum2 at 16 degrees C in contrast to the IMP density of 400/mum2 in the other glial membranes. After acclimation to 5, 16 and 26 degrees C, the loose myelin glial membranes show variations in the density of their larger IMP population; in animals acclimated over 3 or more weeks to 5 degrees C, the number of these IMPs is significantly (P less than 0.001) less per unit area than in animals acclimated to 16 or 26 degrees C. The size of the particles at 5 degrees C is significantly (P less than 0.001) smaller than those at 16 or 26 degrees C. When animals are subjected to a sudden differential in ambient temperature, from 26 or 16 to 5 degrees C, or from 5 to 26 degrees C, and their giant axons with encompassing glia are fixed and frozen 30 min after this temperature change, the IMP population of the glial membranes remaining does not appear to alter. The differences in the IMP population of the myelinating glial membranes at different temperatures may reflect the extent to which they insulate and/or influence the velocity of impulse propagation.

Acclimatization↗
PubMed1981

Effect of dietary lipid on the acyl group composition of glycerophospholipids of brain endothelial cells in the developing rat.

The effects of dietary lipid on the acyl group composition of glycerophospholipids of isolated brain endothelial cell fractions have been determined in the developing rat. Rats were fed high-protein diets containing differing dietary linoleic/linolenic acid ratios but having a similar caloric percentage, or were fed a fat-free diet. With a diet supplemented with corn oil (linoleic/linolenic ratio, 47:1), the proportion of acyl groups of the linolenic acid series (n-3) declines in all glycerophospholipid fractions compared with the controls (linoleic/linolenic ratio, 8.5:1), but the proportion of linoleic acid series (n-6) tends to rise. Consequently, the n-6/n-3 ratio of these glycerophospholipids is markedly higher with corn oil than the control diet. N-9 groups (oleic acid series) are consistently lower in proportion. With fat-free diet, the proportion of n-9 groups is higher in these glycerophospholipids than in the controls, but there is no change in the n-6/n-3 ratio. Comparing the changes produced in the adult and the developing cell fraction, the developing cell fraction is more responsive to dietary influence than that of the adult.

Animals↗
PubMed1981

Glycerophospholipids and acyl group changes in rat brain capillary endothelial cell fraction and the liver during development.

The glycerophospholipid (GPL) content and the acyl group compositions of the ethanolamine and choline glycerophospholipids (EGP, CGP) of the isolated brain capillary cell fractions of the developing rat have been determined. The proportion of EGP/GPL increases during development, whilst CGP/GPL declines: consequently EGP/CGP increases with age. The acyl group compositions of the plasmenylethanolamine (P-GPE) and the diacyl glycerophosphocholine (D-GPC) also change during development, the proportions of saturated fatty acids (SFAs) declining and n-6 groups rising. The rates of accumulation of individual acyl groups of EGP and CGP are highest between the ages of 15 and 20 days; particularly evident is the increase in the medium chain SFAs: 16:0 and 18:0, the monoene 18:1n-9 (oleic acid) and the major-occurring polyunsaturated fatty acid, arachidonic acid, in these GPLs. These changes are compared with those of the liver where the proportion of EGP/CGP remains constant and the acyl group compositions are relatively unchanged during development. Consequently, the rates of accumulation of individual acyl groups of EGP and CGP in liver remain constant or rise slightly during this age period. These results are compared with existing accounts of the desaturation capabilities of brain and liver with age.

Aging↗
PubMed1981

Comparative studies on glial markers.

Macromolecular markers for glial cells have been sought for a variety of reasons. One of the earliest was the need for a means of assessing the purity of cell and subcellular fractions prepared from nervous tissue. While there is still a requirement for this kind of tool, emphasis has shifted towards seeking information on biochemical differentiation among cells and their functional interactions. A brief general review will be made of glial markers and two of these, 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) and glutamine synthetase (GS), will be considered in detail. Until recently studies of markers have been concentrated on the higher vertebrates and those on lower vertebrates and invertebrates have hardly begun. However, such comparative studies may lead to fresh insight into old problems. For example, CNP has long been regarded as a marker for myelin and oligodendrocytes but it has not been possible to attribute a functional role to it and its relation to myelination has remained obscure. The finding that it is present in the glia of a moth Manduca sexta which lacks myelin provides a stimulus for a fresh approach to the problem. Another example is provided by studies on GS. This enzyme is found in astrocyte feet and preliminary results indicate that it is localized also in the perineurial glia of Aplysia ganglia. These results lead to a reconsideration of the perennial question of the possible role of astrocyte feet in barrier mechanisms. Extension of comparative studies may not only raise new questions but also provide some answers.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1980

Influence of diet on the acyl composition of phospholipids in endothelial cells and mitochondria of rat brain.

The effect of diet on phospholipid acyl groups of rat brain endothelial cells and mitochondria and of liver was determined. Rats were fed high-protein diets with a 4:1 linoleate/linolenate ratio but with 4.4%, 1.9%, or 0.8% of the caloric content provided by these essential fatty acids (cal % EFA) or were fed a fat-free diet. In capillary endothelial cells the greatest change occurred in the plasmalogen ethanolamine fraction, there being a significant reduction in the n-3 series of acyl groups and increase in the n-9 series as the cal % EFA was reduced. Other phospholipid fractions changed little. More pronounced changes occurred in brain mitochondria and liver phospholipids. The small changes in capillary endothelia with cal % EFA are in contrast to the great changes produced by a change in the linoleate/linolenate ratio. As the ratio is reduced, there is a progressive increase in the n-3 series in all phospholipid fractions.

Animals↗
PubMed1980

Changes in the content and acyl group composition of glycerophospholipids of brain endothelial cells of the developing rat.

The glycerophospholipid (GPL) content and acyl group compositions of isolated brain endothelial fractions have been determined in the developing rat. During development there is a marked change in the proportions of ethanolamine glycerophospholipids (EGP) to choline glycerophospholipids (CGP), the former rising while CGP falls with age. The acyl group compositions of plasmenylethanolamine (P-GPE) and 1,2-diacyl-sn-glycero-3-phosphocholine (D-GPC) after significantly during development; both show a decline in saturated fatty acids (SFAs) and a rise in the n-6/SFA ratio, in contrast to a constancy in composition of 1,2-diacyl-sn-glycero-3-phosphoethanolamine (D-GPE). The degree of change in the acyl group composition in a particular GPL fraction is related to the rate of its accumulation and to the proportional increase in concentration, fractions accumulating most rapidly or increasing markedly in concentration showing the greatest acyl group compositional change. The possible significance of the high proportion of SFAs in P-GPE and D-GPC fractions in the developing brain endothelial fraction is discussed in relation to the altering blood-brain barrier capacities observed with age.

Animals↗
PubMed1980

Distribution of neurofilaments in myelinated axons of the optic nerve of goldfish (Carassius auratus L.).

Neurofilaments were counted in myelinated axons of the optic nerve of goldfish which were acclimated to 5 degrees and 25 degrees C. The number of neurofilaments increases markedly with increasing axonal size; axons of less than 0.1 micrometer 2 in area contain between 25 and 60 neurofilaments, while in the larger axons of area greater than 1.0 micrometer 2 there are approximately 190. The densities of the neurofilaments in the small axons are noticeably higher than in the larger ones (507 and 160, respectively). A variety of fixation procedures i.e. osmium tetroxide (OsO4) in phosphate buffer, glutaraldehyde (4%) in phosphate buffer or in ethyleneglycol-bis-(beta-aminoethyl ether)-N,N'-tetraacetic acid (EGTA) and piperazine-N-N'-bis-(2-ethanesulphonic acid) (PIPES) and post-fixed with OsO4 had no effect on the numbers of neurofilaments relative to the size of axon. The anaesthetic MS-222 (tricaine methanesulphonate) likewise had no effect on the numbers of neurofilaments. It is proposed that temperature acclimation alters the axon diameter concomitant with an alteration in the number of neurofilaments to fit the new diameter of the axons.

Acclimatization↗
PubMed1979

Isolated brain capillary endothelia: influence of various levels of essential fatty acids on the acyl group composition of glycerophospholipids.

On day seven of gestation. Wistar rats were assigned to a high essential fatty acid (EFA), low EFA, or a fat free diet. The same diets were continued during lactation. On weaning, the offspring were fed the same diets as their mother. Rats were killed at 222 days, brain capillary endothelia isolated, and total lipids extracted from the purified capillaries. The composition of the constituent fatty acids of ethanolamine glycerophospholipid (EGP), choline glycerophospholipid (CGP), and the alk-1-enyl EGP composition from each diet is reported. A decrease in dietary EFA led to reduced proportions of total saturated acyl groups in EGP with no change observed in the total saturated acyl groups from CGP, and an increase in monoenoic fatty acids, particularly 18:1n-9 for each phospholipid class. The proportions of 20:4n-6 in alk-1-enyl EGP were reduced in fat-free fed animals. In addition, the relationship between 20:3n-9 and 20:4n-6 fatty acids in brain capillary endothelia were markedly increased with a reduction in dietary fat. Low EFA and fat deficient animals showed a tendency to sequester 22:6n-3.

Animals↗
PubMed1977

Neurofibrillar changes in goldfish (Carassius auratus L.) brain in relation to environmental temperature.

Neurofibrillar changes occur in the brains of goldfish, Carassius auratus L., maintained at 5 degrees C for 177 days or more under a 12-hour photoperiod. In paraffin sections impregnated by the silver method of Holmes, the light microscopic appearance of the neurofibrillary change was evidenced by black rings 1 micrometer to 2 micrometer in outside diameter. A quantitative study showed the mean number of rings to be: optic tectum layer 3, 1.34 X 10(2)/mm(3), layer 5, 1.14 X 10(2)/MM(3), nucleus prerotundus 4.63 X 10(2)/mm(3), olfactory bulbs, 6.2 X 10(2)/mm3. In the brains of fish kept at 15 degrees C a few rings are found only in some olfactory bulbs and not in any other region of the brain. The brain wet weight also changes and was found to be significantly (p less than 0.01) less in 5 degrees C than in 15 degrees C fish, the mean values being 0.1588 g and 0.2091 g respectively. The significance of the observed changes is discussed. It is suggested that the smaller brain wet weight may reflect a change in the vasculature of the brain and be related to the acclimation process. It is hypothesized that the rings are a morphological expression of a physiological change caused by prolonged exposure to low temperatures; a neuronal response reflecting either early degeneration or a functional adaptation which may involve an alteration in axoplasmic transport. It is suggested that this system is a useful model for the study of relationships between neurofibrillar disturbances and neuronal function.

Animals↗
PubMed1977

Lipid and fatty acyl composition of rat brain capillary endothelia isolated by a new technique.

A method is described for the isolation of pure capillary endothelia from rat brain and the phosphlipid composition of these cells is reported. This method is rapid and requires only a small amount of starting material. It involves: (a) tissue disruption by high speed homogenization, (b) separation of the capillary endothelia from other brain structures using sucrose gradients, and (c) a final purification using a glass bead column. Choline and ethanolamine phosphoglycerides were found to be the predominant lipid classes of these cells amounting to 31.9% and 24.4%, respectively, of total phospholipids. The choline phosphoglycerides consisted almost exclusively of 1,2-diacyl glycerophosphorylcholine, whereas the ethanolamine phosphoglycerides consisted of approximately equal amounts of 1,2-diacyl and 1-alk-1'-enyl-2-acyl glycerophosphorylethanolamine. The composition of the constituent fatty acids of both choline and ethanolamine phosphoglycerides and the alk-1-enyl composition of ethanolamine phosphoglycerides is reported. Saturated fatty acids accounted for 45% of the total fatty acids in choline phosphoglycerides and for 53% in ethanolamine phosphoglycerides. Arachidonic acid accounted for approximately 48% of the total fatty acids in alk-1-enyl ethanolamine phosphoglyceride.

Animals↗
PubMed1977

Neurofilamentous changes in goldfish (Carassius auratus L.) brain in relation to environmental temperature.

The presence of neurofilaments in the synaptic boutons in the brains of goldfish maintained at 5 degrees C for 177 days or more is reported. Neurofilaments are not found in boutons of control fish kept at 15degreesC. It is suggested that the neurofilaments may be equated with neurofibrillary rings seen by light microscopy. Neurofilaments have been implicated in axoplasmic transport and, therefore, irregularities in the occurrence or appearance of these filaments may reflect alterations in their functions. The unusual occurrence of neurofilaments in the boutons of cold temperature goldfish may be an expression of early degenerative changes or may represent a modification of axoplasmic transport. The suitability of goldfish as a model for the study of the functional effects of neurofibrillary/neurofilamentous accumulations is discussed.

Animals↗
PubMed1976

Morphological and biochemical characterization of light and heavy myelin isolated from developing rat brain.

Myelin from developing rat brains was separated on a discontinuous sucrose gradient into subfractions of two different densities, i.e. light and heavy myelin. Electron photomicrographs showed that heavy myelin consisted primarily of large compacted multilamellar structures with a distinct intraperiod line characteristic of myelin in situ. Light myelin, on the other hand, was composed of small vesicles having a unilamellar structure. Similar to whole myelin, both membrane subfractions were highly enriched in 2',3'-cyclic nucleotide-3'-phosphohydrolase. The specific activity of the enzyme, however, showed no developmental trend. Both subfractions contained all the four major proteins characteristic of the whole myelin membrane. There were, however, quantitative differences in the relative distribution of these proteins between light and heavy myelin. Basic protein accounted for 55% and proteolipid protein for 46% of the total myelin proteins of light and heavy myelin, respectively. DM-20 (Agrawal, H.C., Burton, R. M., Fishman, M.A., Mitchell, R.F. and Prensky, A.L. (1972) J. Neurochem. 19, 2083-2089) exhibited a developmental "switch" between light and heavy myelin. Light myelin appeared to contain more DM-20 in 15- to 20-day-old rat brain, whereas the concentration of this protein was higher in heavy myelin at subsequent ages studied.

Aging↗