Embryonic surface antigens: A “quasi-endodermal” teratoma antigen

Hyperimmune antisera against a teratoma-derived endodermal carcinoma of the mouse were used in cytotoxicity tests and by absorption analysis to define a surface antigen. This antigen was found to be present on all tumor cells tested that were of endodermal origin as well as on embryonic liver, and was therefore designated “Endo.” Further testing, however, revealed that Endo was represented on several inappropriate cell types such as young embryos before the appearance of endoderm, sperm, and a small proportion of non-endodermal tumors. Endo must therefore be considered a “quasi-endodermal” antigen.     

A new model for very low density lipoprotein metabolism—Nomenclature for very low density lipoprotein derivatives

A new model for the catabolism of very low density lipoprotein will be proposed following a brief discussion of the relevant information about its metabolism. This model is based on the assumption that each very low density lipoprotein derivative has a distinct structural feature which determines its biological fate. Since this unique determinant may reside in only a small portion of the particles, such as apoprotein, the different very low density lipoprotein derivatives may possess similar or even identical electrophoretic mobility or hydrated density. For this reason, we propose that very low density lipoprotein derivatives be defined according to their putative position in the metabolic pathways rather than according to their hydrated density or their electrophoretic behavior. Thus it is recommended that biochemical separation methods based on principles other than electrophoretic mobility or hydrated density be used to isolate, purify and define very low density lipoprotein derivatives. The position that a lipoprotein particle occupies in the catabolic pathways should be determined by its ability to interact with liver cells or its ability to become converted to low density lipoprotein. This new nomenclature would eliminate unnecessary confusion and stimulate more research toward elucidating the unique structural feature of each very low density lipoprotein derivative.     

“Silenced” polydendrocytes: a new cell type within the oligodendrocyte progenitor cell population?

Oligodendrocyte progenitor cells (OPCs) were first described more than two decades ago. Novel labeling techniques have shown them to be cells with more than just progenitor functions, with their classification as a fourth glial cell type in addition to astrocytes, oligodendrocytes, and microglial cells. Another term used for this cell type is polydendrocytes, owing to both their morphology and to the evolving knowledge about their diverse functions. Recently, an exclusive hallmark of neurons—the generation of action potentials—became debatable, because a subset of polydendrocytes was reported to generate action potentials in response to adequate stimuli. The new technique of inducible reporter gene expression has brought new insights into the fate and function of polydendrocytes. In recent studies, so-called “silenced” OPCs were detected in cortical tissue, and which underwent proliferation with subsequent cell cycle exit, but without any signs of differentiation. Within this review, we focus on the identification of this new subset of polydendrocytes and their possible functions within cortical networks.     

A new polymorphic marker of the T-cell antigen receptor α chain genes in man

The restriction fragment length polymorphism of the unrearranged T-cell antigen receptor (Tcr) chain gene was investigated. Taq I digests, when probed with a Tcr chain cDNA probe, revealed polymorphic bands of 7.0, 2.0, and 1.4 kb, due to variations around the C gene, and the V gene cluster. Family studies confirmed the segregation of these polymorphic bands as allelic markers. These polymorphisms provide a new marker for the analysis of genetic variation of the Tcr a chain, and the influence of variation of the Tcr genes on the immune response.     

5-hydroxymethylcytosine in DNA repair: A new player or a red herring?

Active DNA demethylation performed by ten-eleven translocation (TET) enzymes produces 5-hydroxymethylcytosines, 5-formylcytosines, and 5-carboxylcytosines. Recent observations suggest that 5-hydroxymethylcytosine is a stable epigenetic mark rather than merely an intermediate of DNA demethylation. However, the clear functional role of this new epigenetic player is elusive. The contribution of 5-hydroxymethylation to DNA repair is being discussed currently. Recently, Jiang and colleagues have demonstrated that DNA damage response-activated ATR kinase phosphorylates TET3 in mammalian cells and promotes DNA demethylation and 5-hydroxymethylcytosine accumulation. Moreover, TET3 catalytic activity is important for proper DNA repair and cell survival. Here, we discuss recent studies on the potential role of 5-hydroxymethylation in DNA repair and genome integrity maintenance.     

Red blood cell washing,nitrite therapy,and antiheme therapies prevent stored red blood cell toxicity after trauma–hemorrhage

Transfusion of stored red blood cells (RBCs) is associated with increased morbidity and mortality in trauma patients. Pro-oxidant, pro-inflammatory, and nitric oxide (NO) scavenging properties of stored RBCs are thought to underlie this association. In this study we determined the effects of RBC washing and nitrite and antiheme therapy on stored RBC-dependent toxicity in the setting of trauma-induced hemorrhage. A murine (C57BL/6) model of trauma–hemorrhage and resuscitation with 1 or 3 units of RBCs stored for 0–10 days was used. Tested variables included washing RBCs to remove lower MW components that scavenge NO, NO-repletion therapy using nitrite, or mitigation of free heme toxicity by heme scavenging or preventing TLR4 activation. Stored RBC toxicity was determined by assessment of acute lung injury indices (airway edema and inflammation) and survival. Transfusion with 5 day RBCs increased acute lung injury indexed by BAL protein and neutrophil accumulation. Washing 5 day RBCs prior to transfusion did not decrease this injury, whereas nitrite therapy did. Transfusion with 10 day RBCs elicited a more severe injury resulting in ~90% lethality, compared to <15% with 5 day RBCs. Both washing and nitrite therapy significantly protected against 10 day RBC-induced lethality, suggesting that washing may be protective when the injury stimulus is more severe. Finally, a spectral deconvolution assay was developed to simultaneously measure free heme and hemoglobin in stored RBC supernatants, which demonstrated significant increases of both in stored human and mouse RBCs. Transfusion with free heme partially recapitulated the toxicity mediated by stored RBCs. Furthermore, inhibition of TLR4 signaling, which is stimulated by heme, using TAK-242, or hemopexin-dependent sequestration of free heme significantly protected against both 5 day and 10 day mouse RBC-dependent toxicity. These data suggest that RBC washing, nitrite therapy, and/or antiheme and TLR4 strategies may prevent stored RBC toxicities.     

Hibernation in reptiles—II. Changes in blood cell glucose,haemoglobin, red blood cell count,protein and non-protein nitrogen

• 1.1. The level of blood glucose, red blood cell count, haemoglobin, serum protein and non-protein nitrogen were studied during summer and winter periods.
• 2.2. During hibernation, the first four blood constituents were respectively decreased by 62·35 per cent, 34·18 per cent, 35·33 per cent and 7·19 per cent as there is no food supply during the inactive hibernation season.
• 3.3. Non-protein nitrogen was increased by 115·27 per cent during hibernation. This is due to the accumulation of nitrogenous excretory end metabolites as excretion of the animal is impaired during this period.

     

Maplexins, new α-glucosidase inhibitors from red maple (Acer rubrum) stems

Thirteen gallic acid derivatives including five new gallotannins, named maplexins A-E, were isolated from red maple (Acer rubrum) stems. The compounds were identified by spectral analyses. The maplexins varied in number and location of galloyl groups attached to 1,5-anhydro-d-glucitol. The isolates were evaluated for α-glucosidase inhibitory and antioxidant activities. Maplexin E, the first compound identified with three galloyl groups linked to three different positions of 1,5-anhydro-d-glucitol, was 20 fold more potent than the α-glucosidase inhibitory drug, Acarbose (IC(50)=8 vs 160 μM). Structure-activity related studies suggested that both number and position of galloyls attached to 1,5-anhydro-d-glucitol were important for α-glucosidase inhibition.     

A new complementing cell line for replication-incompetent E1–deleted adenovirus propagation

Recombinant adenoviruses (Ad) are being explored as promising delivery systems for gene therapy and vaccination. However, there is a concern about the possibility of generating replication-competent adenoviruses (RCA) using the human embryonic kidney 293 cell line. We have constructed a new cell line named the UR cell line which can be used to produce Ad vectors free of RCA. This cell line is based on the human embryonic lung HEL 299 cell. We first constructed a shuttle plasmid which encodes the E1A/E1B sequence that is necessary for adenovirus replication. The shuttle plasmid was then transfected into HEL 299 cells. The presence of the E1A/E1B sequence and protein expression in the stably transformed UR cells was confirmed. Viruses produced in UR cells were still RCA-free after ten test passages, while adenovirus produced in 293 cells had generated RCA during the fourth passage. We conclude that the UR cell line is sufficiently stable, can effectively produce a virus yield comparable with 293 cells, and does not generate RCA formation during Ad propagation.     

A new protein (J1-31 antigen, 30 kD) is expressed by astrocytes,Müller glia and ependyma

Monoclonal antibody (MAb) J1-31 raised using human brain homogenate as immunogen in mice can be used as a cell type marker for certain types of CNS macroglia, namely astrocytes, Müller cells and tanycytes as well as ciliated ependymal cells. Except for the ciliated ependymal cells, these types of macroglia express glial fibrillary acidic protein (GFAP). J1-31 antigen is an intracellular protein which has a MW of 30 kD under reducing conditions for gel electrophoresis (Singhet al., 1986). This protein is distinct from GFAP (MW 50 kD) and vimentin (MW 55 kD), the two core proteins of 10 nm IFs known to be expressed in the above types ofmacroglia. This conclusion is based on several criteria including temporal differences in the onset of expression of GFAP and J1-31 antigen during development of the rat cerebellum. Also, there is no detectable (by immunofluorescence microscopy) expression of J1-31 antigen in the prenatal CNS or outside the CNS where vimentin has been reported to be abundant. The most direct evidence that J 1-31 antigen and GFAP are distinct proteins comes from studies on the mature ciliated ependymal cells which do not express GFAP and yet show intense immunostaining for J1-31 antigen.     

A new method of bipolymerase sequencing prevents “stop-bands”

This article presents a relatively quick and cost-effective DNA sequencing method that prevents the formation of stop-bands. This method uses a combination ofTaq and Sequenase that allows sequencing at both low and high temperatures. The ability to sequence at a high temperature appears to be the fundamental component in preventing stop-band formation in G + C rich regions.     

“Natural” chicken antibodies to red blood cells are mainly directed against the B-G antigen,and their occurrence is independent of spontaneous autoimmune thyroiditis

Using an indirect hemagglutination assay we tested sera from 94 healthy normal White Leghorn (NWL) and 117 Obese strain (OS) chickens with spontaneous autoimmune thyroiditis for the presence of natural antibodies against major histocompatibility complex (MHC) antigens expressed on red blood cells (RBC). In both groups older animals had a significantly increased frequency of such antibodies, but the titer was age-independent. OS chickens showed almost the same frequency of natural antibodies as NWL, and a comparison between OS birds with high antithyroglobulin autoantibody (Tg-AAb) titers and those with low titers also did not reveal a significant difference. We conclude that the occurrence of natural antibodies has no relation to Tg-AAb. The specificity of natural antibodies for MHC-encoded antigens was investigated in indirect immunofluorescence tests including absorption experiments with RBC and white blood cells (WBC). This analysis revealed that of 14 MHC-specific sera 13 were reacting with the B-G antigen, which is present on RBC only. One serum reacted with the B-F antigen, expressed on all somatic cells, i. e., both on RBC and WBC.     

A symbiotic relationship of energy metabolism between a ‘non-glycolytic’ mammalian red cell and the liver

The red cell of newborn pig loses the ability to carry out glycolysis within a month after birth. The metabolic energy source for this ‘non-glycolytic’ mammalian red cell is unknown. Hepatectomy of an adult pig results in the loss of red cell ATP with a characteristic half-time of 7–8 h which is identical to the rate with which ATP disappears in the pig cells under in vitro substrate-free incubation. Exposure of pig red cells with either normal or depleted levels of ATP to isolated hepatocytes causes a net synthesis of red cell ATP during a 12 h incubation. These findings suggest that a symbiotic relationship of energy metabolism may exist between the red cell and the liver of the pig.     

A new method for choosing the computational cell in stochastic reaction–diffusion systems

How to choose the computational compartment or cell size for the stochastic simulation of a reaction–diffusion system is still an open problem, and a number of criteria have been suggested. A generalized measure of the noise for finite-dimensional systems based on the largest eigenvalue of the covariance matrix of the number of molecules of all species has been suggested as a measure of the overall fluctuations in a multivariate system, and we apply it here to a discretized reaction–diffusion system. We show that for a broad class of first-order reaction networks this measure converges to the square root of the reciprocal of the smallest mean species number in a compartment at the steady state. We show that a suitably re-normalized measure stabilizes as the volume of a cell approaches zero, which leads to a criterion for the maximum volume of the compartments in a computational grid. We then derive a new criterion based on the sensitivity of the entire network, not just of the fastest step, that predicts a grid size that assures that the concentrations of all species converge to a spatially-uniform solution. This criterion applies for all orders of reactions and for reaction rate functions derived from singular perturbation or other reduction methods, and encompasses both diffusing and non-diffusing species. We show that this predicts the maximal allowable volume found in a linear problem, and we illustrate our results with an example motivated by anterior-posterior pattern formation in Drosophila, and with several other examples.