Karl Bernhard

Bio: Karl Bernhard is an academic researcher from University of Basel. The author has contributed to research in topics: Fatty acid & Triple bond. The author has an hindex of 13, co-authored 49 publications receiving 580 citations.

Fettsäuresynthese im Rattenhirn

Abstract: Pure cerebrosides, sphingomyelines, lecithines and neutral fats were isolated from brains of young rats 6 and 72 hours after intracerebral injection of 14C acetate. We detected the composition of their fatty acids and determined the specific activities. The highest value was always found in palmitic acid which obviously is the precursor for the formation of the other fatty acids. The applied activity incorporated in the fatty acids of lecithines and neutral fats was much higher than the amount concerning cerebrosides and sphingomyelines. Therefore these two lipid fractions showed a much lower turnover.

Über eine biologische Bedeutung der Gallenfarbstoffe. Bilirubin und Biliverdin als Antioxydantien für das Vitamin A und die essentiellen Fettsäuren

Abstract: Rats with a thoracic duct fistula absorb vitamin A and β-carotene very poorly in the total absence of bile from the intestine. Administration of taurocholic acid improves the degree of absorption but fails to raise it to its normal level. It was demonstrated in vitro that small quantities of bilirubin and biliverdin exert a stabilizing action towards vitamin A. Consequently, it may be assumed that the bile pigments play the same role in vivo, serving as natural antioxidants which protect easily oxidizable substances from destruction in the intestinal tract.

Zur papierchromatographischen Analyse von Fettsäuregemischen aus gesättigten und ungesättigten Fettsäuren mit 12 bis 22 C-Atomen

Abstract: A method is described by which saturated and unsaturated fatty acids with 12–22 C atoms can be separated by paper chromatography. By measuring the light absorption of the copper-ferrocyanide complexes developed from the fatty acids on the paper a satisfactory quantitative analysis of such fatty acid mixtures was possible.

Versuche zur quantitativen Erfassung der bei der Resorption von Neutralfett eintretenden Spaltung

Abstract: An investigation was carried out on the absorption of neutral fats, with the purpose of studying the hydrolysis taking place during this process.

Vitamin E und Arachidonsäure‐Bildung in der Leber

Abstract: The liver lipids of rats on a vitamin E-free diet showed much higher contents of arachidonic acid than control animals receiving α-Tocopherol.

Bilirubin is an antioxidant of possible physiological importance

Abstract: Bilirubin, the end product of heme catabolism in mammals, is generally regarded as a potentially cytotoxic, lipid-soluble waste product that needs to be excreted. However, it is here that bilirubin, at micromolar concentrations in vitro, efficiently scavenges peroxyl radicals generated chemically in either homogeneous solution or multilamellar liposomes. The antioxidant activity of bilirubin increases as the experimental concentration of oxygen is decreased from 20% (that of normal air) to 2% (physiologically relevant concentration). Furthermore, under 2% oxygen, in liposomes, bilirubin suppresses the oxidation more than alpha-tocopherol, which is regarded as the best antioxidant of lipid peroxidation. The data support the idea of a "beneficial" role for bilirubin as a physiological, chain-breaking antioxidant.

Different faces of the heme-heme oxygenase system in inflammation

Abstract: The heme-heme oxygenase system has recently been recognized to possess important regulatory properties. It is tightly involved in both physiological as well as pathophysiological processes, such as cytoprotection, apoptosis, and inflammation. Heme functions as a double-edged sword. In moderate quantities and bound to protein, it forms an essential element for various biological processes, but when unleashed in large amounts, it can become toxic by mediating oxidative stress and inflammation. The effect of this free heme on the vascular system is determined by extracellular factors, such as hemoglobin/heme-binding proteins, haptoglobin, albumin, and hemopexin, and intracellular factors, including heme oxygenases and ferritin. Heme oxygenase (HO) enzyme activity results in the degradation of heme and the production of iron, carbon monoxide, and biliverdin. All these heme-degradation products are potentially toxic, but may also provide strong cytoprotection, depending on the generated amounts and the microenvironment. Pre-induction of HO activity has been demonstrated to ameliorate inflammation and mediate potent resistance to oxidative injury. A better understanding of the complex heme-heme

Heme oxygenase-1-derived bilirubin ameliorates postischemic myocardial dysfunction.

Abstract: Bilirubin is a potent antioxidant generated intracellularly during the degradation of heme by the enzyme heme oxygenase. The purpose of this study was to determine the role of increased cardiac bilirubin in protection against postischemic myocardial dysfunction. Rat hearts were isolated and perfused according to the Langendorff technique to evaluate the recovery of myocardial function after 30 min of global ischemia and 60 min of reperfusion. We found that upregulation of the inducible isoform of heme oxygenase (HO-1) by treatment of animals with hemin 24 h before ischemia ameliorated myocardial function and reduced infarct size (tetrazolium staining) on reperfusion of isolated hearts. Tin protoporphyrin IX, an inhibitor of heme oxygenase activity, completely abolished the improved postischemic myocardial performance observed after hemin-mediated HO-1 induction. Likewise, cardiac tissue injury was exacerbated by treatment with tin protoporphyrin IX. Increased cardiac HO-1 expression and heme oxygenase activity were associated with enhanced tissue bilirubin content and an increased rate of bilirubin release into the perfusion buffer. Furthermore, exogenously administered bilirubin at concentrations as low as 100 nanomolar significantly restored myocardial function and minimized both infarct size and mitochondrial damage on reperfusion. Our data provide strong evidence for a primary role of HO-1-derived bilirubin in cardioprotection against reperfusion injury.

Bilirubin Benefits: Cellular Protection by a Biliverdin Reductase Antioxidant Cycle

Abstract: Bilirubin is widely known as an end product of heme metabolism. Very high levels of serum bilirubin lead to its accumulation in the brain, causing kernicterus.1,2 Almost all newborns display some level of jaundice, and some display high enough serum bilirubin levels that phototherapy or exchange transfusion is considered. What most of the medical profession has not appreciated is that, from a teleologic perspective, biosynthesis of bilirubin as the key catabolite of heme does not seem to make sense. Bilirubin is a secondary degradation product of heme. Heme is best known as a constituent of hemoglobin, which is released in association with the breakdown of aging red blood cells. Heme also is contained in a wide range of enzymes whose turnover also leads to free heme release. Free heme can be toxic, so nature evolved a family of heme oxygenase enzymes to degrade heme,3,4 and their blockade leads to greatly increased excretion of unmetabolized heme in the bile.5 These enzymes cleave the heme ring to form biliverdin, iron, and a 1-carbon fragment as carbon monoxide (CO; Fig 1). CO is increasingly appreciated as a neurotransmitter,6,7 and iron, itself toxic, is excreted from cells by a recently characterized pump.8–11 Biliverdin would seem to be an appropriate end product of the pathway, being readily excreted in the bile to enter the intestine and leave the body in the feces. Indeed, in birds, reptiles, and amphibians, biliverdin is the predominant end product of heme degradation.12 For reasons that until now have seemed obscure, in mammals, biliverdin undergoes additional metabolism, being reduced by biliverdin reductase (BVR) to bilirubin, a step that consumes the energy resource nicotinamide adenine dinucleotide phosphate (NADPH).13 As bilirubin is more hydrophobic and insoluble than biliverdin, … Reprint requests to (S.H.S.) Department of Neuroscience, Johns Hopkins School of Medicine, 725 North Wolfe St, Baltimore, MD 21205. E-mail: ssnyder{at}bs.jhmi.edu