trans-10,cis-12-Conjugated Linoleic Acid Instigates Inflammation in Human Adipocytes Compared with Preadipocytes

We showed previously in cultures of primary human adipocytes and preadipocytes that lipopolysaccharide and trans-10,cis-12-conjugated linoleic acid (10,12-CLA) activate the inflammatory signaling that promotes insulin resistance. Because our published data demonstrated that preadipocytes are the primary instigators of inflammatory signaling in lipopolysaccharide-treated cultures, we hypothesized that they played the same role in 10,12-CLA-mediated inflammation. To test this hypothesis, we employed four distinct models. In model 1, a differentiation model, CLA activation of MAPK and induction of interleukin-8 (IL-8), IL-6, IL-1β, and cyclo-oxygenase-2 (COX-2) were greatest in differentiated compared with undifferentiated cultures. In model 2, a cell separation model, the mRNA levels of these inflammatory proteins were increased by 10,12-CLA compared with bovine serum albumin vehicle in the adipocyte fraction and the preadipocyte fraction. In model 3, a co-culture insert model, inserts containing ∼50% adipocytes (AD50) or ∼100% preadipocytes (AD0) were suspended over wells containing AD50 or AD0 cultures. 10,12-CLA-induced IL-8, IL-6, IL-1β, and COX-2 mRNA levels were highest in AD50 cultures when co-cultured with AD0 inserts. In model 4, a conditioned medium (CM) model, CM collected from CLA-treated AD50 but not AD0 cultures induced IL-8 and IL-6 mRNA levels and activated phosphorylation of MAPK in naive AD0 and AD50 cultures. Consistent with these data, 10,12-CLA-mediated secretions of IL-8 and IL-6 from AD50 cultures were higher than from AD0 cultures. Notably, blocking adipocytokine secretion prevented the inflammatory capacity of CM from 10,12-CLA-treated cultures. These data suggest that CLA instigates the release of inflammatory signals from adipocytes that subsequently activate adjacent preadipocytes.     

Die bakterienflora der pupiparen (Diptera). Eine symbiosestudie an blutsaugenden insekten

Ohne Zusammenfassung     

Evaluation of materials for louse control

A simple procedure for evaluation of the effectiveness of different louse-killing substances is described. Factors likely to influence the results are discussed, and it is shown to what extent differences in age, mode of application and interaction of carriers are able to influence the insecticidal effect. A number of substances was tested by the methods described and their potency against lice determined by comparison of the minimum time of exposure necessary to give 100% kill.     

Das verhalten der kleiderlaus bei ausschaltung ihrer symbionten

Ohne Zusammenfassung     

Thrombin receptor activating peptides induce Ca2+ mobilization,barrier dysfunction,prostaglandin synthesis,and platelet-derived growth factor mRNA expression in cultured endothelium

Endothelial cell activation by thrombin is a key event in wound healing, Inflammation, and hemostasis. To better define thrombin-endothelial cell interactions we synthesized several peptides of varying length corresponding to the initial 14 amino acid sequence of the cloned human platelet thrombin receptor after cleavage at an arginine⁴¹ site (R/SFLLRNPNDKYEPF). Thrombin receptor activating peptides (TRAPs) as short as 5 amino acids induced significant levels of PGl₂ synthesis and expression of PDGF mRNA in human endothelium and produced dose-dependent cellular contraction and permeability of confluent human umbilical vein and bovine pulmonary artery endothelial monolayers. To explore whether TRAPs utilized similar signal transducing pathways as α-thrombin to accomplish endothelial cell activation, phospholipase C production of the Ca²⁺ secretagogue IP₃ was measured and detected 10 seconds after either TRAP 7 or α-thrombin. Furthermore, TRAPs ranging from 5-14 residues induced significant dose-dependent incsreases in Fura-2 fluorescence indicative of Ca²⁺ ₁ mobilization. These results indicate that thrombin-mediated proteolytic cleavage of the human and bovine thrombin receptor initiates stimulus/coupling respones such phospholipase C activation, Ca²⁺ mobilization, and protein kinase C activation. The functional consequence of this cellular activation via the cleaved receptor is enhanced cellular contraction, barrier dysfunction, PGI₂ synthesis, and expression of PDGF mRNA. © 1993 Wiley-Liss, Inc.     

Determining the oxidation states of manganese in PC12 and nerve growth factor-induced PC12 cells

Excessive brain Mn can produce toxicity with symptoms resembling parkinsonism. This syndrome, called "manganism," correlates with loss of dopamine in the striatum and cell death in the striatum and globus pallidus. A common hypothesis is that cell damage in Mn toxicity is caused by oxidation of important cell components by Mn3+. Determination of the amount of Mn3+ present, under a range of conditions, in neuronal cells and brain mitochondria represents an important step in evaluating the "damage through oxidation by Mn3+ hypothesis." In an earlier paper we used X-ray absorption near-edge structure (XANES) spectroscopy to determine the amount of Mn2+ and Mn3+ in brain mitochondria under a range of conditions. Here we extend the study to investigate the evidence for formation of Mn3+ through oxidation of Mn2+ by ROS in PC12 cells and in PC12 cells induced with nerve growth factor (NGF) to display a phenotype more like that of neurons. Although the results suggest that very small amounts of Mn3+ might be present at low Mn levels, probably in Mn superoxide dismutase, Mn3+ is not stabilized by complex formation in these cells and therefore does not accumulate to detectable amounts.     

Role of Branched-Chain Aminotransferase Isoenzymes and Gabapentin in Neurotransmitter Metabolism

Abstract: Because it is well known that excess branched-chain amino acids (BCAAs) have a profound influence on neurological function, studies were conducted to determine the impact of BCAAs on neuronal and astrocytic metabolism and on trafficking between neurons and astrocytes. The first step in the metabolism of BCAAs is transamination with α-ketoglutarate to form the branched-chain α-keto acids (BCKAs). The brain is unique in that it expresses two separate branched-chain aminotransferase (BCAT) isoenzymes. One is the common peripheral form [mitochondrial (BCATm)], and the other [cytosolic (BCATc)] is unique to cerebral tissue, placenta, and ovaries. Therefore, attempts were made to define the isoenzymes' spatial distribution and whether they might play separate metabolic roles. Studies were conducted on primary rat brain cell cultures enriched in either astroglia or neurons. The data show that over time BCATm becomes the predominant isoenzyme in astrocyte cultures and that BCATc is prominent in early neuronal cultures. The data also show that gabapentin, a structural analogue of leucine with anticonvulsant properties, is a competitive inhibitor of BCATc but that it does not inhibit BCATm. Metabolic studies indicated that BCAAs promote the efflux of glutamine from astrocytes and that gabapentin can replace leucine as an exchange substrate. Studying astrocyte-enriched cultures in the presence of [U-¹⁴C]glutamate we found that BCKAs, but not BCAAs, stimulate glutamate transamination to α-ketoglutarate and thus irreversible decarboxylation of glutamate to pyruvate and lactate, thereby promoting glutamate oxidative breakdown. Oxidation of glutamate appeared to be largely dependent on the presence of an α-keto acid acceptor for transamination in astrocyte cultures and independent of astrocytic glutamate dehydrogenase activity. The data are discussed in terms of a putative BCAA/BCKA shuttle, where BCATs and BCAAs provide the amino group for glutamate synthesis from α-ketoglutarate via BCATm in astrocytes and thereby promote glutamine transfer to neurons, whereas BCATc reaminates the amino acids in neurons for another cycle.     

Lipid Peroxidation and Changes of Trace Elements in Mice Treated with Paradichlorobenzene

Paradichlorobenzene (pDCB) has been used as a space deodorant and moth repellant, as well as an intermediate in the chemical industry. Given its broad applications and high volatility, considerable concern exists regarding the adverse health effects of pDCB in the home and the workplace. In this study, changes in lipid peroxidation, antioxidants, and trace element levels in the liver and kidney of pDCB-treated mice were investigated to determine their roles in toxicity. Mice were orally gavaged once daily for seven consecutive days with pDCB (0 (corn oil control), 450, and 900 mg/kg). The level of malondialdehyde (MDA), an end product of lipid peroxidation, markedly increased in the high-dose pDCB group in both the liver and kidney compared with the control group. Changes in hepatic levels of reduced glutathione (GSH) in the pDCB groups were indistinguishable from the control group, while renal levels of reduced GSH in the high-dose pDCB group were significantly lowered in comparison to the control and the low-dose groups. Superoxide dismutase (SOD) activity in the liver of mice treated with pDCB showed a downward trend, whereas there was no consistent trend associated with changes in SOD activity in the kidney. Additionally, renal iron levels in the high-dose pDCB group were significantly decreased compared with the low-dose group and the controls, whereas hepatic iron content in the low-dose pDCB group was significantly lower compared with the controls. Selenium and zinc levels in the kidney were both significantly decreased in the high-dose pDCB group vs. the control and low-dose groups. There were no treatment-induced changes in copper levels in either the kidney or liver. However, a significant increase was found in the liver zinc/copper ratio in the high-dose pDCB group vs. the controls. In addition, blood zinc levels showed a downward trend with increased pDCB dosage. These results suggest that pDCB toxicity is mediated by oxidative damage and tissue-specific alterations in trace element levels both in the liver and the kidney of mice.