[Entrez medline Query] 13 citations found Other Formats: [Citation Format] [MEDLINE Format] Links: [106 medline neighbors] Ciba Found Symp 1988;140:67-91 Localization and catabolism of cyanogenic glycosides. Poulton JE Department of Botany, University of Iowa, Iowa City 52242. The catabolism of cyanogenic glycosides is initiated by cleavage of the carbohydrate moiety by one or more beta-glycosidases, which yields the corresponding alpha-hydroxynitrile. Until recently, the mode by which cyanogenic disaccharides are hydrolysed was largely unclear. Investigation of highly purified beta-glycosidases from plants containing cyanogenic disaccharides has now indicated that these compounds may be degraded via two distinct pathways, depending on the plant species. beta-Glycosidases from Davallia trichomanoides and Vicia angustifolia hydrolysed (R)-vicianin and (R)-amygdalin at the aglycone-disaccharide bond producing mandelonitrile and the corresponding disaccharide. Alternatively, hydrolysis of cyanogenic disaccharides in Prunus serotina, almonds, and Linum usitatissimum involves stepwise removal of the sugar residues. The nature of these enzymes and of other beta-glycosidases responsible for hydrolysis of simple cyanogenic monosaccharides is discussed. Hydroxynitriles may decompose either spontaneously or enzymically in the presence of a hydroxynitrile lyase to produce hydrogen cyanide and an aldehyde or ketone. The major kinetic and molecular properties of hydroxynitrile lyases purified from species accumulating aromatic and aliphatic cyanogens are reviewed. Cyanogenesis occurs rapidly only after cyanogenic plant tissues are macerated, allowing glycosides access to their catabolic enzymes. The possible nature of the compartmentation which prevents cyanogenesis under normal physiological conditions is discussed in relation to our knowledge of the tissue and subcellular localizations of cyanogens and catabolic enzymes. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [202 medline neighbors] J Biochem (Tokyo) 1987 Apr;101(4):847-854 Purification and properties of beta-D-glucosidase (linamarase) from the butter bean, Phaseolus lunatus. Itoh-Nashida T, Hiraiwa M, Uda Y A beta-D-glucosidase (linamarase) was purified 11,700-fold from the butter bean, Phaseolus lunatus L., by means of successive procedures including extraction, ammonium sulfate fractionation, acetone treatment, and chromatographies on CM-Sephadex, DEAE-Sephadex, and Sephadex G-200. The final preparation gave a single protein band on both disc polyacrylamide gel electrophoresis and SDS-polyacrylamide gel electrophoresis. In spite of its electrophoretic purity, the final enzyme preparation showed four glycosidase activities; beta-D-glucosidase, beta-D-galactosidase, beta-D-fucosidase, and beta-D-xylosidase. The molecular weight of the enzyme was determined to be 124,000 +/- 9,000 by Sephadex G-200 gel filtration, and 59,000 +/- 2,400 by SDS-disc gel electrophoresis. The enzyme showed a pH optimum in the range of 5.1 to 6.0 with p-nitrophenyl beta-D-glucoside, 4-methylumbelliferyl beta-D-glucoside, and linamarin. Among natural substrates containing a beta-glucosyl terminal, linamarin, prunasin, and salicin were hydrolyzed by the enzyme from butter beans, but amygdalin, cellobiose, gentiobiose, and laminarin were hardly hydrolyzed. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [119 medline neighbors] Ann Emerg Med 1986 Sep;15(9):1067-1074 Clinical toxicology of cyanide. Hall AH, Rumack BH Cyanide poisoning causes a high incidence of severe symptomatology and fatality. There are numerous sources of potential cyanide exposure. Without the history of cyanide exposure, diagnosis is often difficult. Treatment with supportive measures and available specific and efficacious antidotes frequently allows survival. The toxicology of cyanide, including sources, clinical features, diagnosis, and treatment, is reviewed. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [122 medline neighbors] Chung Kuo Yao Li Hsueh Pao 1986 Sep;7(5):460-462 Pharmacokinetics of amygdalin in rabbits. [Article in Chinese] Zhang GM, Jin BQ --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [104 medline neighbors] Planta Med 1986 Aug;4:275-278 Antitussive effects of L-ephedrine, amygdalin, and makyokansekito (Chinese traditional medicine) using a cough model induced by sulfur dioxide gas in mice. Miyagoshi M, Amagaya S, Ogihara Y --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [159 medline neighbors] Pediatrics 1986 Aug;78(2):269-272 Cyanide poisoning from laetrile ingestion: role of nitrite therapy. Hall AH, Linden CH, Kulig KW, Rumack BH A 4-year-old child ingested laetrile and almost died of cyanide poisoning. Treatment with the Lilly cyanide antidote kit resulted in rapid, complete recovery. Extremely high whole blood cyanide levels were documented. The necessity for use of the antidote kit in serious cyanide poisoning has recently been questioned. This case demonstrates benefit from antidotal treatment. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [107 medline neighbors] Biochem Pharmacol 1986 Jul 1;35(13):2123-2128 Intestinal first pass metabolism of amygdalin in the rat in vitro. Strugala GJ, Rauws AG, Elbers R The intestinal first pass metabolism of amygdalin has been investigated in rat small intestine in vitro. The results show that amygdalin is hydrolyzed to prunasin, essentially in the wall of the proximal jejunum. This specific beta(1-6)hydrolytic cleavage of the terminal glucose residue is pH-dependent and can be inhibited by glucono-delta-lactone, a potent inhibitor of the lysosomal beta-glucosidase of the rat intestine. No substrate competition between phloridzin and lactose vs amygdalin was noted. None of the more common soluble beta- or alpha-enzymatic activities of mammalian intestine (alpha-glucosidase, alpha-amylase) or mammalian liver (beta-galactosidase, beta-glucuronidase) were capable of catalyzing the hydrolysis of the terminal glucose from amygdalin at pH's 5.0, 7.0 or 9.0. Furthermore, no metabolic activity of isolated rat livers toward amygdalin and prunasin was observed within two hours of recirculating perfusion. However, cecal contents of conventional rats, exhibited both amygdalin- and prunasin-hydrolyzing activities. The resulting mandelonitrile dissociates spontaneously into cyanide and benzaldehyde. Therefore, our findings indicate that metabolism of amygdalin to prunasin occurring in the proximal part of jejunum is apparently mediated by enzymatic beta(1-6)glucosidase activity of the gut wall. In contrast, the toxicity of amygdalin due to the release of cyanide obviously requires microbiological activities of the gut flora. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [127 medline neighbors] Arch Biochem Biophys 1986 Jun;247(2):433-439 Comparison of kinetic and molecular properties of two forms of amygdalin hydrolase from black cherry (Prunus serotina Ehrh.) seeds. Kuroki GW, Poulton JE Two forms of the beta-glucosidase amygdalin hydrolase (AH I and II), which catalyze the hydrolysis of (R)-amygdalin to (R)-prunasin and D-glucose, have been purified over 200-fold from mature black cherry (Prunus serotina Ehrh.) seeds. These proteins showed very similar molecular and kinetic properties but could be resolved by chromatofocusing and isoelectric focusing. AH I and II were monomeric (Mr 60,000) and had isoelectric points of 6.6 and 6.5, respectively. Their glycoprotein character was indicated by positive periodic acid-Schiff staining and by their binding to concanavalin A-Sepharose 4B with subsequent elution by alpha-Me-D-glucoside. Of the natural glycosidic substrates tested, both enzymes showed a pronounced preference for the endogenous cyanogenic disaccharide (R)-amygdalin. They also hydrolyzed at the same active site the synthetic substrates p-nitrophenyl-beta-D-glucoside and 4-methylumbelliferyl-beta-D-glucoside but were inactive towards (R)-prunasin, p-nitrophenyl-alpha-D-glucoside, and 4-methylumbelliferyl-alpha-D-glucoside. Maximum hydrolytic activity was shown in citrate-phosphate buffer in the pH range 4.5-5.0. AH I and II were inhibited competitively by the reaction product (R)-prunasin and noncompetitively (mixed type) by delta-gluconolactone and castanospermine. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [60 medline neighbors] Food Chem Toxicol 1986 May;24(5):417-420 Comparative metabolism of linamarin and amygdalin in hamsters. Frakes RA, Sharma RP, Willhite CC Rates of cyanide liberation resulting from hydrolysis of the cyanogenic glycosides linamarin, amygdalin and prunasin by a crude beta-glucosidase prepared from hamster caecum were studied in vitro. In addition, hamster blood cyanide and thiocyanate concentrations were determined at 0.5, 1, 2, 3 and 4 hr after an oral dose of 0.44 mmol linamarin or amygdalin/kg body weight. Plots of cyanide liberated v. time for linamarin and prunasin yielded straight lines. A similar plot for amygdalin was curvilinear, with the rate of cyanide release increasing with time. At 10(-3) M substrate concentrations, the average rates of hydrolysis of prunasin, amygdalin and linamarin were 1.39, 0.57 and 0.13 nmol/min/mg protein, respectively. Lineweaver-Burk plots yielded apparent Km and Vmax values of 3.63 X 10(-5) M and 0.35 nmol/min/mg protein, respectively, for amygdalin, and 7.33 X 10(-3) M and 1.04 nmol/min/mg protein, respectively, for linamarin. Blood cyanide concentrations following amygdalin treatment reached their highest level (130 nmol/ml) 1 hr after dosing and remained elevated until 3 hr after treatment. Blood cyanide concentrations following linamarin treatment reached their highest level (116 nmol/ml) after 3 hr and then declined immediately. Area under the blood cyanide concentration-time curve was 395 nmol-hr/ml for amygdalin and 318 nmol-hr/ml for linamarin. The results suggest a faster rate of enzymatic hydrolysis and cyanide absorption for amygdalin than for linamarin. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [115 medline neighbors] CA Cancer J Clin 1986 May;36(3):185-189 The metabolic cancer therapy of Harold W. Manner, Ph.D. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [117 medline neighbors] South Med J 1986 Feb;79(2):259-260 Laetrile intoxication and hepatic necrosis: a possible association. Leor R, Michaeli J, Brezis M, Stessman J A 65-year-old woman with cirrhosis and hepatoma lapsed into deep coma, hypotension, and acidosis after ingestion of 3 gm of Laetrile, a cyanogenetic glucoside. After initial treatment, the patient regained consciousness, but massive hepatic damage led to her death. We suggested a possible relationship between Laetrile poisoning and massive hepatic necrosis. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [107 medline neighbors] Women Health 1986;11(3-4):165-178 The deadliest delusion: unproven methods in the management of cancer. Brown HG In spite of major advances in cancer treatment over the past decades, unproven or ineffective methods of treatment continue to be offered to the public by unqualified or unscrupulous practitioners. These methods fall into five categories: devices, tests, drugs, diets, and psychological methods, as well as combinations of these. The emotional, physical, and financial burdens of cancer treatment make cancer patients and their families especially vulnerable to the pitch of these operators. Participation in worthless treatments can lead to loss of life or prolongation of illness which might otherwise have been avoided through orthodox cancer treatment. Ineffective treatments can generally be recognized by application of some simple guidelines. Lack of faith in the medical care system is an important motivation in the choice of alternative therapies. Health practitioners have an obligation to be sensitive to patients' needs, and to provide emotional as well as medical support, to communicate openly with patients and families, and to nurture the trust that will prevent abandonment of traditional medical care in favor of quackery. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [201 medline neighbors] Arch Biochem Biophys 1985 Dec;243(2):361-373 Isolation and characterization of two cyanogenic beta-glucosidases from flax seeds. Fan TW, Conn EE Two cyanogenic beta-glucosidases, linustatinase and linamarase, were isolated and purified from flax seeds (Linum ussitatissimum). They catalyze the sequential hydrolysis of linustatin and neolinustatin to yield acetone and methylethyl ketone cyanohydrins, respectively. The purification procedure for linustatinase involved acetone extraction, precipitation by polyethyleneimine and ammonium sulfate (40-80% saturation), and Red A gel, concanavalin A-Sepharose, and PBE 94 column chromatography; that for linamarase was similar except that polyethyleneimine precipitation was eliminated and DE-52 and Sepharose CL-6B replaced Red A gel column chromatography. The native substrates neolinustatin and linamarin were used for the assay during purification. Both proteins were purified to electrophoretic homogeneity. Linustatinase is an alpha beta dimer (molecular weights of alpha and beta = 39,000 and 19,000, respectively) while linamarase appears to be an alpha 5 beta 5 decamer (molecular weights of alpha and beta = 62,500 and 65,000, respectively). Both enzymes contain mannose or glucose. Linustatinase exists in five different isozymic forms (isoelectric points between 7 and 8) whereas linamarase occurs in one major form (isoelectric point 4 to 5). The kinetic parameters of the two enzymes are similar: acidic pH optima, Km's in the millimolar range, and competitive inhibition by delta-gluconolactone, a transition state analog. The presence of an aglycone structure in the substrates is important for both enzyme activities. In addition, both enzymes are specific towards the beta-glycosidic linkage; linustatinase (a beta-bis-glucosidase) readily hydrolyzes beta-bis-glucosides with 1,6 and 1,3 linkages whereas linamarase (a beta-monoglucosidase) exhibits little activity towards these substrates. --------------------------------------------------------------------------- the above reports in format. ---------------------------------------------------------------------------