scholarly journals Quantitative Studies of White Matter

1961 ◽  
Vol 44 (3) ◽  
pp. 487-498 ◽  
Author(s):  
D. B. McDougal ◽  
D.W. Schulz ◽  
J.V. Passonneau ◽  
J. R. Clark ◽  
M. A. Reynolds ◽  
...  
Keyword(s):  
White Matter ◽  
Glucose Metabolism ◽  
Olfactory Bulb ◽  
Metabolic Activity ◽  
Lipid Content ◽  
O2 Uptake ◽  
Phosphogluconate Dehydrogenase ◽  
Quantitative Studies ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
High Metabolic Activity

Total lipid and six enzymes closely related to the metabolism of glucose-6-phosphate have been measured in ten tracts of the rabbit. Lipid content appears to be a valid indicator of the degree of myelination. Heavily myelinated tracts have much larger amounts of glucose-6-phosphate dehydrogenase than lightly myelinated ones but there is no corresponding difference in 6-phosphogluconate dehydrogenase. In fact the ratios between the two enzymes were found to vary over a ninefold range. Hexokinase is found in largest amounts in tracts with relatively little lipid, and this tends to be true for phosphofructokinase as well. The fibrillar layer of olfactory bulb is exceptional with regard to both enzymes, and to glucose-6-phosphate dehydrogenase. The enzymes are present in amounts which are more than adequate to support glucose metabolism at a rate commensurate with the known rates of O2 uptake by various tracts. The distribution of some of the enzymes is compatible with the notion that the nodes of Ranvier are regions of high metabolic activity. A simple algebraic relationship is found to hold fairly well for the distribution of four of the enzymes among the tracts.

scholarly journals Quantitative Studies of White Matter

1964 ◽  
Vol 47 (3) ◽  
pp. 419-432 ◽  
Author(s):  
D. B. McDougal ◽  
Robert T. Schimke ◽  
Elizabeth M. Jones ◽  
Elizabeth Touhill
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
White Matter ◽  
Olfactory Bulb ◽  
Dehydrogenase Activity ◽  
Lipid Content ◽  
Lipid Synthesis ◽  
Adult Brain ◽  
Primary Role ◽  
Quantitative Studies

Methods for measurement of glyceraldehyde-P dehydrogenase, triose-P isomerase, fructose 1,6-diphosphate aldolase, and the DPN-linked and flavin-linked α-glycero-P dehydrogenases in small amounts of tissue have been worked out. These enzymes have been measured in ten tracts in rabbit central nervous system. The activities of all the enzymes measured, except the flavin-linked α-glycero-P dehydrogenase, are present in larger amounts in lightly myelinated than in heavily myelinated tracts, but are relatively low in fibrillar layer of olfactory bulb, which is unmyelinated. Aldolase, like P-fructokinase (measured previously), is especially low in fibrillar layer. Taken together with relatively high 6-P-gluconate dehydrogenase activity found earlier this supports the hypothesis that the pentose-P shunt is particularly active in this tract. The activity of DPN-linked α-glycero-P dehydrogenase is inversely proportional to the lipid content of the myelinated tracts, which suggests that its primary role is not related to lipid synthesis in adult brain. The activities of flavin-linked α-glycero-P dehydrogenase are unrelated to those of the DPN-linked enzyme, which is contrary to expectation if the two enzymes function as partners in the "α-glycerophosphate shuttle."

Role of pentose phosphate pathway in lipid accumulation of oleaginous fungus Mucor circinelloides

RSC Advances ◽  
2015 ◽  
Vol 5 (118) ◽  
pp. 97658-97664 ◽  
Author(s):  
Lina Zhao ◽  
Xin Tang ◽  
Xiao Luan ◽  
Haiqin Chen ◽  
Yong Q. Chen ◽  
...  
Keyword(s):  
Lipid Content ◽  
Pentose Phosphate Pathway ◽  
Lipid Accumulation ◽  
Dry Weight ◽  
Mucor Circinelloides ◽  
Pentose Phosphate ◽  
Phosphogluconate Dehydrogenase ◽  
Oleaginous Fungus ◽  
Glucose 6 Phosphate Dehydrogenase

Overexpressing the genes coding for glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase from the pentose phosphate pathway in the oleaginous fungusMucor circinelloidesincreased the lipid content of cell dry weight by 20–30%.

Ultrastructural aspects of gymnosperms reproductive organs tissues due to their functional condition

1978 ◽  
Vol 36 (2) ◽  
pp. 440-441
Author(s):  
G. M. Kozubov
Keyword(s):  
Metabolic Activity ◽  
Functional Condition ◽  
Reproductive Organs ◽  
Considerable Change ◽  
Complicated Structure ◽  
Tetrad Stage ◽  
Ubisch Bodies ◽  
Similar Organization ◽  
Female Reproductive Organs ◽  
High Metabolic Activity

The ultrastructure of reproductive organs of pine, spruce, larch and ginkgo was investigated. It was found that the male reproductive organs possess similar organization. The most considerable change in the ultrastructure of the microsporocytes occur in meiosis. Sporoderm is being laid at the late tetrad stage. The cells of the male gameto-phyte are distinguished according to the metabolic activity of the or- ganells. They are most weakly developed in the spermiogenic cell. Ta-petum of the gymnosperms is of the periplasmodic - secretorial type. The Ubisch bodies which possess similar structure in the types investigated but are specific in details in different species are produced in tapetum.Parietal and subepidermal layers are distinguished for their high metabolic activity and are capable of the autonomous photosynthesis. Female reproductive organs differ more greatly in their struture and have the most complicated structure in primitive groups. On the first stages of their formation the inner cells of nucellus are transformed into the nucellar tapetum in which the structures similar to the Ubisch bodies taking part in the formation of the sporoderm of female gametophyte have been found.

scholarly journals Topographic patterns of white matter hyperintensities are associated with multimodal neuroimaging biomarkers of Alzheimer’s disease

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Malo Gaubert ◽  
Catharina Lange ◽  
Antoine Garnier-Crussard ◽  
Theresa Köbe ◽  
Salma Bougacha ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
White Matter ◽  
Glucose Metabolism ◽  
Corpus Callosum ◽  
Gray Matter ◽  
Fdg Pet ◽  
White Matter Hyperintensities ◽  
Gray Matter Volume ◽  
Matter Volume

Abstract Background White matter hyperintensities (WMH) are frequently found in Alzheimer’s disease (AD). Commonly considered as a marker of cerebrovascular disease, regional WMH may be related to pathological hallmarks of AD, including beta-amyloid (Aβ) plaques and neurodegeneration. The aim of this study was to examine the regional distribution of WMH associated with Aβ burden, glucose hypometabolism, and gray matter volume reduction. Methods In a total of 155 participants (IMAP+ cohort) across the cognitive continuum from normal cognition to AD dementia, FLAIR MRI, AV45-PET, FDG-PET, and T1 MRI were acquired. WMH were automatically segmented from FLAIR images. Mean levels of neocortical Aβ deposition (AV45-PET), temporo-parietal glucose metabolism (FDG-PET), and medial-temporal gray matter volume (GMV) were extracted from processed images using established AD meta-signature templates. Associations between AD brain biomarkers and WMH, as assessed in region-of-interest and voxel-wise, were examined, adjusting for age, sex, education, and systolic blood pressure. Results There were no significant associations between global Aβ burden and region-specific WMH. Voxel-wise WMH in the splenium of the corpus callosum correlated with greater Aβ deposition at a more liberal threshold. Region- and voxel-based WMH in the posterior corpus callosum, along with parietal, occipital, and frontal areas, were associated with lower temporo-parietal glucose metabolism. Similarly, lower medial-temporal GMV correlated with WMH in the posterior corpus callosum in addition to parietal, occipital, and fontal areas. Conclusions This study demonstrates that local white matter damage is correlated with multimodal brain biomarkers of AD. Our results highlight modality-specific topographic patterns of WMH, which converged in the posterior white matter. Overall, these cross-sectional findings corroborate associations of regional WMH with AD-typical Aß deposition and neurodegeneration.

scholarly journals Simultaneous Catabolite Repression between Glucose and Toluene Metabolism in Pseudomonas putida Is Channeled through Different Signaling Pathways

2007 ◽  
Vol 189 (18) ◽  
pp. 6602-6610 ◽  
Author(s):  
Teresa del Castillo ◽  
Juan L. Ramos
Keyword(s):  
Glucose Metabolism ◽  
Pseudomonas Putida ◽  
Catabolite Repression ◽  
Carbon Sources ◽  
Flux Analysis ◽  
Glucose Determination ◽  
Net Flux ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Metabolism Gene

ABSTRACT Pseudomonas putida KT2440(pWW0) can use toluene via the TOL plasmid-encoded catabolic pathways and can use glucose via a series of three peripheral chromosome-encoded routes that convert glucose into 6-phosphogluconate (6PG), namely, the glucokinase pathway, in which glucose is transformed to 6PG through the action of glucokinase and glucose-6-phosphate dehydrogenase. Alternatively, glucose can be oxidized to gluconate, which can be phosphorylated by gluconokinase to 6PG or oxidized to 2-ketogluconate, which, in turn, is converted into 6PG. Our results show that KT2440 metabolizes glucose and toluene simultaneously, as revealed by net flux analysis of [13C]glucose. Determination of glucokinase and gluconokinase activities in glucose metabolism, gene expression assays using a fusion of the promoter of the Pu TOL upper pathway to ′lacZ, and global transcriptomic assays revealed simultaneous catabolite repression in the use of these two carbon sources. The effect of toluene on glucose metabolism was directed to the glucokinase branch and did not affect gluconate metabolism. Catabolite repression of the glucokinase pathway and the TOL pathway was triggered by two different catabolite repression systems. Expression from Pu was repressed mainly via PtsN in response to high levels of 2-dehydro-3-deoxygluconate-6-phosphate, whereas repression of the glucokinase pathway was channeled through Crc.

scholarly journals Effects on Cancellous Bone in the Metaphysis

2017 ◽  
Vol 45 (7) ◽  
pp. 876-878 ◽  
Author(s):  
Kathryn E. Gropp
Keyword(s):  
Cancellous Bone ◽  
Metabolic Activity ◽  
Morphologic Changes ◽  
High Metabolic Activity

Cancellous bone has high metabolic activity compared to many other bone compartments and can be affected not only by changes in physeal activity but also by perturbations in homeostasis caused by changes in physiology or on-target pharmacology. Examples of several types of resulting morphologic findings were presented; if known, the pathways causing morphologic changes were discussed.

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