Iodomethylated fatty acid metabolism in mice and dogs

The myocardial uptake of fatty acids labeled with radioactive iodine and injected i.v. can only be evaluated with SPECT if their oxidation kinetics is slow enough. For this reason, we evaluated different iodomethylated fatty acids in mice and dogs to determine which of them shows the highest myocardial uptake and the slowest oxidation. The most suitable was found to be 16-iodo-3-methyl hexadecanoic acid (mono ) since its myocardial fixation was the same as that of the reference, i.e. 16-iodo-9-hexadecenoic acid (IHA), whereas it was degraded more slowly. Thirty min after injection of mono into dogs, the decrease in myocardial activity with respect to the maximum was two fold less than after IHA injection. The myocardial uptake of the two dimethylated fatty acids studied, i.e. 16-iodo-2,2-methyl hexadecanoic acid and 16-iodo-3,3-methyl hexadecanoic acid, was less than that of IHA in mice and dogs. In the latter, the myocardial uptake was so small that we were unable to study the time course of its activity. Consequently, these dimethylated fatty acids are not suitable for the study of the myocardial uptake of fatty acids in man.     

An Immunotoxicological Evaluation of 4, 4'-Thiobis-(6-t-butyl-m-cresol) in Female B6C3F1 Mice: 1. Body and Organ Weights, Hematology, Serum Chemistries, Bone Marrow Cellularity, and Hepatic Microsomal Parameters

An Immunotoxicological Evaluation of 4,4'-Thiobis-(6-t-butyl-m77-cresol)in Female B6C3F1 Mice. 1. Body and Organ Weights, Hematology,Serum Chemistries, Bone Marrow Cellularity, and Hepatic MicrosomalParameters. MUNSON, A. E., WHITE, K. L., JR., BARNES, D. W.,MUS-GROVE, D. L., LYSY, H. H., AND HOLSAPPLE, M. P. (1988).Fundam. Appl. Toxicol. 10, 691–700. Adult female B6C3F1mice were gavaged with 4,4'-thiobis-(6-t-butyl-m-cresol) (TBBC)in corn oil at doses of 10, 100, or 200 mg/kg daily for 14 consecutivedays. There was no overt toxicity, as manifested by grosslyobservable behavioral changes, decreased growth rate over theexposure period, or mortality. There were also no marked effectson serum chemistries or hematology, with the exception of asignificant increase (41%) in the number of leukocytes at thehighest dose. Absolute differential counts indicated that significantincreases occurred in the number of lymphocytes (31%) and neutrophils(177%). Studies with bone marrow indicated a significant 30%increase in the number of cells/femur from animals treated withthe highest dose of TBBC. The number of macrophage progenitors(CFU-M)/femur was significantly increased by 28%, while thenumber of granulocyte-monocyte progenitors (CFU-GM)/femur wasnonsig-nificantly increased by 20% in the high dose animals.The weight of both the spleen and liver was increased in a dose-relatedfashion, although the histopathology of the spleen of TBBC-treatedmice was not different from control. The livers of mice receivingthe high dose showed mild focal hydropic degeneration, mildhepatitis, and a slight increase in the number of Kupffer cells.No other organs were affected. Liver microsomal protein andcytochrome P-450 levels were increased in a dose-related fashion.Enzyme activities of aminopyrine demethylase and aniline hydroxylase,but not arylhydrocarbon hydroxylase, were also increased ina dose-related fashion.     

Metabolism of methyl-branched iodo palmitic acids in cultured hepatocytes

The metabolic fate of methyl-branched iodo fatty acids was studied in primary culture of rat hepatocytes. We compared 16-iodo-2-R,S-methyl palmitic acid (2-Me), which can be oxidized, with 16-iodo-3-R,S-methyl palmitic acid (3-Me) which can be oxidized only after an initial oxydation and with 16-iodo-2,2-dimethyl palmitic acid (2,2-Me₂) and 16-iodo-3,3-dimethyl palmitic acid (3,3-Me₂) which cannot be oxidized at all. The normal fate of natural fatty acids was given by comparative experiments with [1-¹⁴C] palmitic acid. Monomethyl-branched iodo fatty acids were taken up in the same range as palmitic acid but more than dimethyl-branched iodo fatty acids. After a 15-h incubation, acido-soluble products (ASP) accounted for 75% of the radioactivity taken up as 16-iodo-2-methyl palmitic acid, 50% as other methyl-branched iodo fatty acids and only 30% as palmitic acid, which indicated that all the methyl-branched iodo fatty acids underwent a strong deiodination process. Fatty acids were esterified in the following order: palmitic acid >16-iodo-3-R,S-methyl palmitic acid>16-iodo-2-R,S-methyl palmitic acid>16-iodo-2,2-dimethyl palmitic acid>16-iodo-3,3-dimethyl palmitic acid. Cultured hepatocytes, labelled for 3 h with the various fatty acids and reincubated for 12 h without fatty acid, secreted large amounts of free dimethylbranched iodo fatty acids as compared to the monomethyl ones and palmitic acid. Only hepatocytes prelabelled with 16-[¹²⁵I]iodo-2,2-dimethyl palmitic acid exhibited an appreciable secretion of labeled triglycerides, but at a lower rate than with [1-¹⁴C] palmitic acid. Conversely, the 16-iodo-monomethyl palmitic acids remained chiefly in hepatocyte triglycerides. Minute amounts of 16-iodo-methyl-branched-palmitic acids were found in hepatocyte or secred phospholipids as compared with palmitic acid. This metabolic fate of methyl-branched iodo palmitic acids argues against their utilization as imaging probes to monitor in vivo the synthesis and the secretion of triglycerides by the liver.     

Immunotoxicity of the Semiconductor Gallium Arsenide in Female B6C3F1 Mice

The effects of gallium arsenide (GaAs) exposure on immunocompetenceof B6C3F1 female mice were investigated. GaAs was administeredas a single intratracheal instillation at doses of 50, 100,and 200 mg/kg. Fourteen days after exposure, various cellularand humoral immune parameters were assessed. GaAs exposure increasedspleen cellularity in a dose-dependent manner. However, thepercentages of Thy 1.2 positive and 1g positive cells were decreasedand that of F4/80 positive cells was increased dose dependency.The IgM and IgG antibody-forming cell response of the spleento the T-dependent antigen sheep erythrocytes was reduced by66 and 48%, respectively, at 200 mg/kg. Levels of the serumcomplement protein, C3, were increased by as much as 16% withno significant change in CH50 levels. The mitogenic responseof splenic T cells to Con A and PHA was unaffected by GaAs,but that of B cells to LPS was increased by 52%. The delayedhypersensitivity response to keyhole limpet hemocyanin and mixedlymphocyte response were significantly reduced in a dose-dependentmanner by GaAs exposure. Natural killer cell activity againstthe YAC-1 mouse lymphoma was enhanced in treated mice. Analysisof peritoneal exudate cells (PEC) revealed a dose-dependentdecrease in number and a shift in the composition of PECs. Thepercentage of PEC monocytes increased from 53% of the populationto 81%, while the lymphocytes decreased from 46 to 20%. Theadherent PEC population demonstrated decreased phagocytosisof covaspheres and increased phagocytosis of chicken erythrocytes(CRBC). GaAs exposure had no effect on host resistance to Plasmodiumyoelii or Streptococcus pneumoniae, but dose dependency increasedresistance of the mouse to Listeria monocytogenes Treated micedemonstrated a significantly decreased resistance to the B16F10melanoma with a sevenfold increase in tumor burden at 200 mg/kg.GaAs affects both humoral and cellular immune parameters inmice and impairs the ability of the immune system to protectagainst B16F10 tumor challenge.     

Auditory evoked potentials to tones and syllables in adults: evidence of specific influence on N250 wave

Brain-derived neurotrophic factor (BDNF) is involved in the differentiation and the survival of neurons. It has also been shown to be associated with the regrowth of neurons of damaged spinal cord and the modulation of ionic currents by acting on sodium channels and NMDA receptors through tyrosine kinase B (TrkB) receptors. We investigated the effects of BDNF on rhythm generation induced by disinhibition in dissociated cultures from embryonic rat spinal cord (E14), with extracellular multisite recordings (MultiElectrode Arrays, MEAs) or intracellular patch-clamp recordings. Exogenous BDNF had only minor effects on the bursting by increasing the activity during the burst. This increase of activity is suggested to be mediated by a potentiation of the postsynaptic NMDA receptors because it has been found that BDNF potentiates the NMDA-evoked depolarization in cultures incubated with BDNF for 10 min. Possible direct effects of BDNF on sodium channels were also investigated by local application of BDNF to the soma of patched neurons but no depolarization was observed. Long-term application of BDNF strongly decreased the activity during the burst and also the number of active electrodes, possibly due to a decrease in network density.     

The modulation of the Ne-like wave on correct responses foreshadows errors

In reaction time (RT) tasks, event-related potentials (ERPs) reveal a response-locked negative wave when subjects commit errors. This wave, termed "error negativity" (Ne) or "error-related negativity" (ERN), is thought to index response-monitoring processes. With conventional monopolar recordings, this negativity is hardly seen on correct responses, likely overlapped by a large positive wave. Indeed, after Laplacian transformation (a spatial high-pass filter), a small Ne-like wave is unmasked. Recently, it has been shown that the positivity on monopolar recordings was larger for correct responses preceding an error than for correct responses preceding a correct trial. After Laplacian transformation, it appears that this effect is due, at least in part, to a decrease of the Ne-like wave on correct responses preceding an error. This result indicates that, as the Ne on errors, the Ne-like wave on correct responses is sensitive to performance and hence is likely related to response-monitoring processes.     

Progress in Rhesus Histocompatibility Typing Resulting from the Second International Nonhuman Primate Histocompatibility Workshop (1973)

The Second International Nonhuman Primate Histocompatibility Workshop permitted comparison of rhesus monkey alloantisera developd in various laboratories on a single common panel of related and unrelated monkeys. Analysis of the data permits the conclusion that at least nine specificities are recognized by more than one laboratory, including six at the first locus and three at the second locus.     

Human ORFeome Version 1.1: A Platform for Reverse Proteomics

The advent of systems biology necessitates the cloning of nearly entire sets of protein-encoding open reading frames (ORFs), or ORFeomes, to allow functional studies of the corresponding proteomes. Here, we describe the generation of a first version of the human ORFeome using a newly improved Gateway recombinational cloning approach. Using the Mammalian Gene Collection (MGC) resource as a starting point, we report the successful cloning of 8076 human ORFs, representing at least 7263 human genes, as mini-pools of PCR-amplified products. These were assembled into the human ORFeome version 1.1 (hORFeome v1.1) collection. After assessing the overall quality of this version, we describe the use of hORFeome v1.1 for heterologous protein expression in two different expression systems at proteome scale. The hORFeome v1.1 represents a central resource for the cloning of large sets of human ORFs in various settings for functional proteomics of many types, and will serve as the foundation for subsequent improved versions of the human ORFeome.