Acetoacetate and Glucose as Lipid Precursors and Energy Substrates in Primary Cultures of Astrocytes and Neurons from Mouse Cerebral Cortex

Primary cultures of astrocytes and neurons derived from neonatal and embryonic mouse cerebral cortex, respectively, were incubated with [3-14C]acetoacetate or [2-14C]glucose. The utilization of glucose and acetoacetate, the production of lactate, D-3-hydroxybutyrate, and 14CO2, and the incorporation of 14C and of 3H from 3H2O into lipids and lipid fractions were measured. Both cell types used acetoacetate as an energy substrate and as a lipid precursor; lactate was the major product of glucose metabolism. About 60% of the acetoacetate that was utilized by neurons was oxidized to CO2, whereas this was only approximately 20% in the case of cultured astrocytes. This indicates that the rate at which 14C-labeled Krebs cycle intermediates exchange with pools of unlabeled intermediates is much higher in astrocytes than in neurons. Acetoacetate is a better precursor for the synthesis of fatty acids and cholesterol than glucose, presumably because it can be used directly in the cytosol for these processes; preferential incorporation into cholesterol was not observed in these in vitro systems. We conclude that ketone bodies can be metabolized both by the glial cells and by the neuronal cells of developing mouse brain.     

Uptake and metabolism of fluorescent ceramide analogs by rat oligodendrocytes in culture.

We studied the metabolism of sphingolipids by oligodendrocytes derived from rat spinal cord by providing lipid vesicles with either N-lissamine-rhodaminyl-ceramide (LRh-Cer) or N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-ceramide (NBD-Cer) to the cells cultured in a chemically-defined medium. With both probes the major fluorescent product turned out to be sphingomyelin (SM). Most of LRh-SM was not cell-associated but recovered from the culture medium, probably due to back-exchange to the lipid vesicles. The accumulation of LRh-SM, both in the cells and in the medium, was inhibited in the presence of monensin or brefeldin A, whereas the production of NBD-SM was much less affected by these Golgi perturbing drugs. With LRh-Cer as substrate, LRh-labelled fatty acid (FA), galactosyl- and sulfogalactosyl-ceramides (GalCer and SGalCer) were also formed. NBD-Cer, however, was metabolized to glucosylceramide (GlcCer) and GalCer but not to SGalCer or NBD-FA. These data demonstrate that chemical modifications of ceramide alter its metabolism in oligodendrocytes and that the metabolites of LRh-Cer reflect the glycolipid composition of myelin more closely than those of NBD-Cer.     

Iron in granulocytes of nephrotic patients determined by Zeeman electrothermal atomic absorption spectrophotometry

One of the major threats to patients undergoing maintenance hemodialysis is an increased susceptibility to infections caused by microorganisms, among whichYersinia orListeria are frequently recovered. In patients receiving hemodialysis, iron overload owing to multiple transfusions plays an important role in the mechanisms underlying the susceptibility to bacterial infections, partially mediated by impaired neutrophil function. In order to assess the true role of iron at the cellular level, an AAS method was developed to measure the iron content of granulocytes. Iron levels in the granulocytes were determined in an apparently healthy population and in a population of iron-overloaded renal hemodialysis patients. Granulocytes were isolated by a method modified from Böyum. The analyses were performed using pyrocoated graphite tubes, and in one of the char steps, oxygen was used to facilitate ashing. The mean iron level found in the granulocytes from apparently normal persons was 4.07 fg/cell (n=17) with a CV of 44%; the mean value for the dialysis patient group was 4.59 fg/cell (n=8) with a CV of 37%. There was no significant difference between the two groups,p=0.70.     

Molecular imaging of rheumatoid arthritis: emerging markers,tools, and techniques

Early diagnosis and effective monitoring of rheumatoid arthritis (RA) are important for a positive outcome. Instant treatment often results in faster reduction of inflammation and, as a consequence, less structural damage. Anatomical imaging techniques have been in use for a long time, facilitating diagnosis and monitoring of RA. However, mere imaging of anatomical structures provides little information on the processes preceding changes in synovial tissue, cartilage, and bone. Molecular imaging might facilitate more effective diagnosis and monitoring in addition to providing new information on the disease pathogenesis. A limiting factor in the development of new molecular imaging techniques is the availability of suitable probes. Here, we review which cells and molecules can be targeted in the RA joint and discuss the advances that have been made in imaging of arthritis with a focus on such molecular targets as folate receptor, F4/80, macrophage mannose receptor, E-selectin, intercellular adhesion molecule-1, phosphatidylserine, and matrix metalloproteinases. In addition, we discuss a new tool that is being introduced in the field, namely the use of nanobodies as tracers. Finally, we describe additional molecules displaying specific features in joint inflammation and propose these as potential new molecular imaging targets, more specifically receptor activator of nuclear factor κB and its ligand, chemokine receptors, vascular cell adhesion molecule-1, α_Vβ₃ integrin, P2X7 receptor, suppression of tumorigenicity 2, dendritic cell-specific transmembrane protein, and osteoclast-stimulatory transmembrane protein.     

Macrophage size determinations in the diagnosis of tuberculous effusions

This study investigated the usefulness of macrophage size determinations in lymphocyte-rich pleural effusions to improve the cytologic diagnosis of tuberculous pleurisy. The size of pleural macrophages was analyzed by quantitative morphometric planimetry in 18 effusions due to tuberculosis, 21 effusions following radiotherapy for malignant disease and 10 effusions due to congestive heart failure. Macrophages were identified and clearly separated from mesothelial cells by latex phagocytosis and immunostaining with the monoclonal antibody My4 (CD14). The mean macrophage area (+/- standard deviation) in tuberculous effusions (92 +/- 14 sq micron) was significantly smaller than in postradiation (141 +/- 28 sq micron) and heart-failure effusions (154 +/- 22 sq micron) (P less than .0001). There was also a smaller ratio of mesothelial cells in tuberculous effusions (0.5 +/- 0.9%) in comparison with effusions following radiotherapy (4 +/- 5%) or congestive heart failure (10 +/- 12%). In summary, this study demonstrated some cytomorphologic parameters that may be helpful in the differential diagnosis of tuberculous effusions.