Effect of roasting on ochratoxin A level in green coffee beans inoculated with Aspergillus ochraceus

The heat stability of ochratoxin A in green coffee beans inoculated with Aspergillus ochraceus was studied. Heat treatment (roasting) at 200 °C for 10 or 20 min reduced the levels of ochratoxin A by only 0–12% in the dried whole beans. Almost all of the ochratoxin A was infused into the coffee decoction when the roasted samples were ground and extracted with boiling water. Therefore, the reduction of ochratoxin A concentration of contaminated coffee beans by roasting under these conditions is ineffective.     

Localization of ornithine decarboxylase in the chick embryo during organogenesis

Summary The localization of ornithine decarboxylase (ODC), a key enzyme in polyamine biosynthesis and thus in cell growth, was determined in the 4.5-day-old chick embryo, using two independent methods of analysis. ODC protein was identified by indirect immunofluorescence with a monospecific ODC antibody, and catalytically active ODC was identified by autoradiography with -(5-³H) difluoromethylornithine. Both methods revealed a basically similar distribution of ODC within the embryo. Among the organs, the brain exhibited the highest ODC levels. ODC levels were also high in spinal cord, mesonephric tubules and heart. Similar levels, but confined to limited areas, were found in liver tissue, head mesenchyme, and the oral and pharyngeal regions. Organs that exhibited high ODC levels are all engaged in rapid growth, as well as in extensive tissue remodeling and differentiation.     

Stellate cells storing retinol in the liver of adult lamprey,Lampetra japonica

Summary Distribution, localization and fine structure of the stellate cells in the liver of lamprey, Lampetra japonica, were studied during the spawning migration by use of Kupffer's gold-chloride method, fluorescence microscopy for vitamin A (retinol) and electron microscopy. The stellate cells in the lamprey liver differ in some of their properties from those in mammalian livers. Stellate cells which store abundant retinol in lipid droplets, occur not only in the hepatic parenchyma, but also in the dense perivascular and capsular connective tissue of the liver and in the interstitium of pancreatic tissue. In the hepatic parenchyma these cells are located perisinusoidally or along thick bundles of collagen fibrils. The stellate cells display a number of large retinol-containing lipid droplets, granular endoplasmic reticulum, tubular structures, dense bodies, Golgi complex, microtubules, and microfilaments. In the space of Disse, the stellate cells and extracellular fibrilar components such as collagen fibrils and microfibrils (11–12 nm in diameter) are intervened between the two layers of basal laminae. Differentiation and possible functions of the stellate cells in the lamprey liver are discussed.     

Enzymic arrangement and allosteric regulation of the aromatic amino acid pathway in Neisseria gonorrhoeae

The pathway construction and allosteric regulation of phenylalanine and tyrosine biosynthesis was examined in Neisseria gonorrhoeae. A single 3-deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthase enzyme sensitive to feedback inhibition by l-phenylalanine was found. Chorismate mutase and prephenate dehydratase appear to co-exist as catalytic components of a bifunctional enzyme, known to be present in related genera. The latter enzyme activities were both feedback inhibited by l-phenylalanine. Prephenate dehydratase was strongly activated by l-tyrosine. NAD⁺-linked prephenate dehydrogenase and arogenate dehydrogenase activities coeluted following ion-exchange chromatography, suggesting their identity as catalytic properties of a single broad-specificity cyclohexadienyl dehydrogenase. Each dehydrogenase activity was inhibited by 4-hydroxyphenylpyruvate, but not by l-tyrosine. Two aromatic aminotransferases were resolved, one preferring the l-phenylalanine:2-ketoglutarate substrate combination and the other preferring the l-tyrosine: 2-ketoglutarate substrate combination. Each aminotransferase was also able to transaminate prephenate. The overall picture of regulation is one in which l-tyrosine modulates l-phenylalanine synthesis via activation of prephenate dehydratase. l-Phenylalanine in turn regulates early-pathway flow through inhibition of DAHP synthase. The recent phylogenetic positioning of N. gonorrhoeae makes it a key reference organism for emerging interpretations about aromatic-pathway evolution.     

The lipopolysaccharide of the green sulfur bacterium Chlorobium vibrioforme f. thiosulfatophilum

The cell wall lipopolysaccharide of the green sulfur bacterium Chlorobium vibrioforme f. thiosulfatophilum was obtained by the phenol-chloroform-petroleum ether and the hot phenol-water methods, respectively. It contained mannose, glucose, galacturonic acid, glucosamine, glycine, and small amounts of rhamnose, galactose and glucuronic acid. In addition to d-glycero-d-mannoheptose, the corespecific constituents 2-keto-3-deoxyoctonate and l-glycero-d-mannoheptose were found. Polyacrylamide gel-electrophoresis in the presence of sodium deoxycholate gave no indication for the presence of O-specific repeating units. Degradation of the lipopolysaccharide required 10% acetic acid (100° C, 2 h). The lipid A moiety contained the total of glucosamine of the lipopolysaccharide as well as small amounts of 2,3-diamino-2,3-dideoxy-glucose. It was phosphate-free. The fatty acid spectrum comprised 3-OH-14:0, 3-OH-16:0, and iso-3-OH-18:0 besides little 12:0, 14:0 and 16:0. Hydroxylaminolysis and sodium methylate treatment revealed all of the three hydroxy fatty acids to be amidebound.Abbreviations DOC sodium deoxycholate - PAGE polyacrylamide gel-electrophoresis     

Role of phospholipases in myocardial ischemia: effect of cardioprotective agents on the phospholipases A of heart cytosol and sarcoplasmic reticulum in vitro

Increased breakdown of myocardial phospholipids to fatty acids and lysophosphoglycerides is an early feature of myocardial ischemic injury and many investigators believe that enhanced phospholipase action is an important factor in the process. Several recent reports indicate that inhibitors of phospholipase A, such as mepacrine, chloroquine and chlorpromazine, can prevent heart phosphoglyceride breakdown in vivo. We isolated the phospholipases A from rat heart cytosol and sarcoplasmic reticulum and examined the effects of various cardioprotective substances on their activity. Most of the cardioprotective agents studied inhibited the heart phospholipases in vitro, providing further evidence that phospholipid degradation in ischemic myocardial injury may be modulated by pharmacologic agents.     

Algesia and local responses induced by neurokinin A and substance P in human skin and temporal muscle

Neurokinin A (NKA), substance P (SP) and the two peptides combined (SP + NKA) were injected intracutaneously on the forearm and into the temporal muscle of healthy volunteers. Pain intensity, cutaneous wheal and flare responses and tenderness of the temporal muscle were quantitated. SP but not NKA induced cutaneous pain. This relates the algesic effect of SP to the specific N-terminal amino acid sequence of the peptide, not shared by NKA. NKA, however, potentiated the algesic effect of SP as SP + NKA induced a significantly prolonged cutaneous pain sensation. Both peptides induced wheals, but only SP induced flare. These results confirm previous studies relating wheal formation to the identical C-terminal amino acid sequence of the two peptides and flare reaction to the N-terminal part of SP. Injections into the temporal muscle did not cause pain or tenderness.     

丽江乌头中的一个新二萜生物碱

从丽江乌头根中分离、鉴定了三个二萜生物碱成分,其中碱Ⅰ、碱Ⅱ分别为已知成分阿克诺辛(aconosine)和嘟拉碱(dolaconine);碱Ⅲ为一新的C_(18)-型二萜生物碱,从MS、IR、~1H NMR、~(13)C NMR等光谱数据推定了其结构,并命名为丽日碱甲(liconosine A)。