Quantitation of 13-hydroxyoctadecadienoic acid (13-HODE) by radioimmunoassay

Antibodies against 13-hydroxyoctadecadienoic acid (13-HODE) were produced in rabbits by immunizing the animal with 13-HODE-thyroglobulin conjugate. The antibodies appeared to be rather specific for 13-HODE since other hydroxy fatty acids showed minimal crossreaction. The radioimmunoassay was capable of detecting 50 pg per assay tube and was applied to the study of the biosynthesis of 13-HODE in platelets and leukocytes. In contrast to reported findings from endothelial cells, A-23187, thrombin and collagen stimulated synthesis and release of 13-HODE from platelets. However, insignificant synthesis of 13-HODE was found in leukocytes following A-23187 stimulation. Exogenous addition of linoleic acid stimulated the synthesis of 13-HODE from both platelets and leukocytes. The majority of 13-HODE synthesized was found in the medium. These studies suggest that both types of blood cells possess active (omega-6) lipoxygenase. Platelets may use endogenously released linoleic acid to synthesize 13-HODE, whereas leukocytes may utilize linoleic acid released from other cell types for 13-HODE synthesis.     

Recovery of (13)CO2 during rest and exercise after [1-(13)C]acetate, [2-(13)C]acetate, and NaH(13)CO3 infusions

For estimating the oxidation rates (Rox) of glucose and other substrates by use of (13)C-labeled tracers, we obtained correction factors to account for label dilution in endogenous bicarbonate pools and TCA cycle exchange reactions. Fractional recoveries of (13)C label in respiratory gases were determined during 225 min of rest and 90 min of leg cycle ergometry at 45 and 65% peak oxygen uptake (VO(2 peak)) after continuous infusions of [1-(13)C]acetate, [2-(13)C]acetate, or NaH(13)CO(3). In parallel trials, [6,6-(2)H]glucose and [1-(13)C]glucose were given. Experiments were conducted after an overnight fast with exercise commencing 12 h after the last meal. During the transition from rest to exercise, CO(2) production increased (P < 0.05) in an intensity-dependent manner. Significant differences were observed in the fractional recoveries of (13)C label as (13)CO(2) at rest (NaH(13)CO(3), 77.5 +/- 2.8%; [1-(13)C]acetate, 49.8 +/- 2.4%; [2-(13)C]acetate, 26.1 +/- 1.4%). During exercise, fractional recoveries of (13)C label from [1-(13)C]acetate, [2-(13)C]acetate, and NaH(13)CO(3) were increased compared with rest. Magnitudes of label recoveries during both exercise intensities were tracer specific (NaH(13)CO(3), 93%; [1-(13)C]acetate, 80%; [2-(13)C]acetate, 65%). Use of an acetate-derived correction factor for estimating glucose oxidation resulted in Rox values in excess (P < 0.05) of glucose rate of disappearance during hard exercise. We conclude that, after an overnight fast: 1) recovery of (13)C label as (13)CO(2) from [(13)C]acetate is decreased compared with bicarbonate; 2) the position of (13)C acetate label affects carbon dilution estimations; 3) recovery of (13)C label increases in the transition from rest to exercise in an isotope-dependent manner; and 4) application of an acetate correction factor in glucose oxidation measurements results in oxidation rates in excess of glucose disappearance during exercise at 65% of VO(2 peak). Therefore, bicarbonate, not acetate, correction factors are advocated for estimating glucose oxidation from carbon tracers in exercising men.     

Translocation (13q21q)

Summary A (13q21q) translocation was found in an infant with Down's syndrome. The 17-year-old mother and the grandmother carried the translocation 45,XX,t(13;21)(p12;q11). The great grandparents had normal karyotypes. Fluorescence marker studies suggested that the translocation originated in the great grandmother. The hypothesis was supported by satellite association studies which showed a significant excess of 13–21 and 13–15 associations in the great grandmother.     

C(13)-substituted bacteriorhodopsin analogs

13-Ethyl-, 13-isopropyl-, 13-tert-butyl-, 13-phenyl-, 13-alpha-naphthyl-, and 13-demethyl-retinals were synthesized and incubated with bacterioopsin (bO) to give the corresponding bacteriorhodopsin (bR) analogs. The capability of the 13-tert-butyl- and 13-alpha-naphthyl-bRs to exist and to photocycle shows that apparently around C(13) of the chromophore there lies a large enough cavity. A study of the light-induced conversions of the artificial pigments prepared has shown that the introduction at position 13 of the chromophore of the hydrocarbon substituents bulkier than that of the natural bR diminished the amplitudes of the electric photoresponses. Bulky C(13)-substituents or absence of substitution at that position decelerated the relaxation of the M-intermediates and disturbed the 13-cis-in equilibrium all-trans-isomerization.     

Author index Volume 13 (2004)

Authors Index

Author index Volume 13 (2004)     

A homologous tandem translocation [45,XX,-13,-13,+t(13;13) (q12;q34)

Chromosomal investigation of a young girl with mental and motor retardation and congenital anomalies revealed a translocation between both members of pair No. 13. Banding analysis showed that the translocation was "tandem," leading to monosomy for segments in both the long and short arms of No. 13.     

The 13th International Workshops on Opportunistic Protists (IWOP13)

The 13th International Workshops on Opportunistic Protists (IWOP‐13) was held November 13–15, 2014 in Seville, Spain. The objectives of the IWOP meetings are to: (1) serve as a forum for exchange of new information among active researchers concerning the basic biology, molecular genetics, immunology, biochemistry, pathogenesis, drug development, therapy, and epidemiology of these immunodeficiency‐associated pathogenic eukaryotic microorganisms that are seen in patients with AIDS and; (2) to foster the entry of new and young investigators into these underserved research areas. The IWOP meeting focuses on opportunistic protists; e.g. the free‐living amoebae, Pneumocystis, Cryptosporidium, Toxoplasma, the Microsporidia, and kinetoplastid flagellates. This conference represents the major conference which brings together research groups working on these opportunistic pathogens. Progress has been achieved on understanding the biology of these pathogenic organisms, their involvement in disease causation in both immune deficient and immune competent hosts and is providing important insights into these emerging and reemerging pathogens. A continuing concern of the participants is the ongoing loss of scientific expertise and diversity in this research community. This decline is due to the small size of these research communities and an ongoing lack of understanding by the broader scientific community of the challenges and limitations faced by researchers working on these organisms, which makes these research communities very sensitive to declines in research funding.     

Interferonregulatoryfactor-8(IRF-8) regulates the expression of matrix metalloproteinase-13 (MMP-13) in chondrocytes

Low levels of inflammation-induced expression of matrix metalloproteinase (MMP) play a crucial role in articular cartilage matrix destruction in osteoarthritis (OA) patients. Interferon regulatory factor-8 (IRF-8), an important member in the IRF family, plays a key role in regulating the inflammation-related signaling pathway. The aim of this study is to investigate the physiological roles of IRF-8 in the pathological progression of OA. We found that IRF-8 was expressed in human primary chondrocytes. Interestingly, the expression of IRF-8 was upregulated in OA chondrocytes. In addition, IRF-8 was increased in response to interleukin-1β (IL-1β) treatment, mediated by the Janus kinase 2 (JAK2) pathway. Overexpression of IRF-8 in human chondrocytes by transduction with lentiviral-IRF-8 exacerbated IL-1β-induced expression of matrix metalloproteinase-13 (MMP-13) in human chondrocytes. In contrast, knockdown of IRF-8 inhibited IL-1β-induced expression of MMP-13. Importantly, IRF-8 could bind to the promoter of MMP-13 and stimulate its activity. Additionally, overexpression of IRF-8 exacerbated IL-1β-induced degradation of type II collagen. However, silencing IRF-8 abrogated the degradation of type II collagen. Taken together, our findings identified a novel function of IRF-8 in regulating articular cartilage matrix destruction by promoting the expression of MMP-13.     

Partial trisomy of 13(pter→q12) due to 47,XY,+der(13),t(13;22)(q12;q13)mat

Summary A 36-month-old boy presented with short stature, short neck, shield-shaped chest, and mental retardation. Chromosome analysis showed trisomy for the short arm and the proximal portion of the long arm of chromosome 13 [47,XY,+der(13),t(13;22)(q12;q13)mat]. The patient's mother has a balanced translocation between the long arms of chromosomes 13 and 22 [46,XX,t(13;22)(q12;q13)]. The patient's neutrophils showed an elevated number of nuclear projections and his fetal hemoglobin level was undetectable.     

Matrix Metalloproteinase-13 (MMP-13) Directly and Indirectly Promotes Tumor Angiogenesis

Matrix metalloproteinases (MMPs) are extracellular zinc-dependent endopeptidases involved in the degradation and remodeling of extracellular matrix in physiological and pathological processes. MMPs also have a role in cell proliferation, migration, differentiation, angiogenesis, and apoptosis. We previously identified cancer invasion-related factors by comparing the gene expression profiles between parent and the highly invasive clone of cancer cells. Matrix metalloproteinase-13 (MMP-13) was identified as a common up-regulated gene by cancer invasion-related factors. Although MMP-13 slightly promoted tumor invasion, we found that MMP-13 was involved in tumor angiogenesis. Conditioned medium from MMP-13-overexpressing cells promoted capillary formation of immortalized human umbilical vein endothelial cells. Furthermore, treatment with recombinant MMP-13 protein enhanced capillary tube formation both in vitro and in vivo. MMP-13-promoted capillary tube formation was mediated by activation of focal adhesion kinase and ERK. Interestingly, MMP-13 promoted the secretion of VEGF-A from fibroblasts and endothelial cells. By immunohistochemical analysis, we found a possible correlation between MMP-13 expression and the number of blood vessels in human cancer cases. In summary, these findings suggest that MMP-13 may directly and indirectly promote tumor angiogenesis.     

13-(S)-hydroxyoctadecadienoic acid (13-HODE) incorporation and conversion to novel products by endothelial cells

13(S)-Hydroxy-[12,13-3H]octadecadienoic acid (13-HODE), a linoleic acid oxidation product that has vasoactive properties, was rapidly taken up by bovine aortic endothelial cells. Most of the 13-HODE was incorporated into phosphatidylcholine, and 80% was present in the sn -2 position. The amount of 13-HODE retained in the cells gradually decreased, and radiolabeled metabolites with shorter reverse-phase high-performance liquid chromatography retention times (RT) than 13-HODE accumulated in the extracellular fluid. The three major metabolites were identified by gas chromatography combined with mass spectrometry as 11-hydroxyhexadecadienoic acid (11-OH-16:2), 9-hydroxytetradecadienoic acid (9-OH-14:2), and 7-hydroxydodecadienoic acid (7-OH-12:2). Most of the radioactivity contained in the cell lipids remained as 13-HODE. However, some 11-OH-16:2 and several unidentified products with longer RT than 13-HODE were detected in the cell lipids. Normal human skin fibroblasts also converted 13-HODE to the three major chain-shortened metabolites, but Zellweger syndrome fibroblasts produced only a very small amount of 11-OH-16:2. Therefore, the chain-shortened products probably are formed primarily by peroxisomal beta-oxidation. These findings suggest that peroxisomal beta-oxidation may constitute a mechanism for the inactivation and removal of 13-HODE from the vascular wall. Because this is a gradual process, some 13-HODE that is initially incorporated remains in endothelial phospholipids, especially phosphatidylcholine. This may be the cause of some of the functional perturbations produced by 13-HODE in the vascular wall.