Two cases of airway dysfunction related to diacetyl exposure / 中华劳动卫生职业病杂志

Occupational exposure to diacetyl can lead to bronchiolitis obliterans. In this paper, two patients with severe obstructive ventilation disorder who were exposed to diacetyl at a fragrance and flavours factory were analyzed. The clinical manifestations were cough and shortness of breath. One of them showed Mosaic shadows and uneven perfusion in both lungs on CT, while the other was normal. Field investigation found that 4 of the 8 workers in the factory were found to have obstructive ventilation disorder, and 2 had small airway dysfunction. This paper summarizes the diagnostic process of patients in order to improve the understanding of airway dysfunction caused by occupational exposure to diacetyl and promote the development of relevant standards.

Effect of pralidoxime on coronary perfusion pressure during cardiopulmonary resuscitation in a pig model

OBJECTIVE: Pralidoxime is widely used for the treatment of organophosphate poisoning. Multiple studies have reported its vasoconstrictive property, which may facilitate the restoration of spontaneous circulation (ROSC) after cardiac arrest by increasing the coronary perfusion pressure (CPP). 2,3-Butanedione monoxime, which belongs to the same oxime family, has been shown to facilitate ROSC by reducing left ventricular ischemic contracture. Because pralidoxime and 2,3-butanedione monoxime have several common mechanisms of action, both drugs may have similar effects on ischemic contracture. Thus, we investigated the effects of pralidoxime administration during cardiopulmonary resuscitation in a pig model with a focus on ischemic contracture and CPP.METHODS: After 14 minutes of untreated ventricular fibrillation, followed by 8 minutes of basic life support, 16 pigs randomly received either 80 mg/kg of pralidoxime (pralidoxime group) or an equivalent volume of saline (control group) during advanced cardiovascular life support (ACLS).RESULTS: Mixed-model analyses of left ventricular wall thickness and chamber area during ACLS revealed no significant group effects or group-time interactions, whereas a mixed-model analysis of the CPP during ACLS revealed a significant group effect (P=0.038) and group-time interaction (P<0.001). Post-hoc analyses revealed significant increases in CPP in the pralidoxime group, starting at 5 minutes after pralidoxime administration. No animal, except one in the pralidoxime group, achieved ROSC; thus, the rate of ROSC did not differ between the two groups.CONCLUSION: In a pig model of cardiac arrest, pralidoxime administered during cardiopulmonary resuscitation did not reduce ischemic contracture; however, it significantly improved CPP.

Effect of 2,3-butanedione monoxime on calcium paradox-induced heart injury in rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the Effect of 2,3-butanedione monoxime (BDM) on calcium paradox-induced heart injury and its underlying mechanisms.</p><p><b>METHODS</b>Thirty-two adult male SD rats were randomized into 4 groups, namely the control group, BDM treatment control group, calcium paradox group, and BDM treatment group. Isolated Sprague Dawley male rat hearts underwent Langendorff perfusion and the left ventricular pressure (LVP) and left ventricular end-diastolic pressure (LVEDP) were monitored. Left ventricular developed pressure (LVDP) was calculated to evaluate the myocardial performance. Lactate dehydrogenase (LDH) content in the coronary flow was determined. Triphenyltetrazolium chloride staining was used to measure the infarct size, and myocardial cell apoptosis was tested with TUNEL method. Western blotting was used to determine the expression of cleaved caspase-3 and cytochrome c.</p><p><b>RESULTS</b>Compared with the control group, BDM at 20 mmol/L had no effect on cardiac performance, cell death, apoptotic index or the content of LDH, cleaved caspase-3 and cytochrome c at the end of perfusion under control conditions (P>0.05). Calcium paradox treatment significantly decreased the cardiac function and the level of LVDP and induced a larger infarct size (P<0.01), an increased myocardial apoptosis index (P<0.01), and up-regulated expressions of cleaved caspase-3 and cytochrome c (P<0.01). BDM (20 mmol/L) significantly attenuated these effects induced by calcium paradox, and markedly down-regulated the levels of LVEDP and LDH (P<0.01), lowered myocardial apoptosis index, decreased the content of cleaved caspase-3 and cytochrome c (P<0.01), increased LVDP, and reduced the infarct size (P<0.01).</p><p><b>CONCLUSION</b>BDM suppresses cell apoptosis and contracture and improves heart function and cell survival in rat hearts exposed to calcium paradox, suggesting the value of BDM as an potential drug for myocardial ischemia reperfusion injur.</p>

Polyamines and Their Metabolites as Diagnostic Markers of Human Diseases

Polyamines, putrescine, spermidine and spermine, are ubiquitous in living cells and are essential for eukaryotic cell growth. These polycations interact with negatively charged molecules such as DNA, RNA, acidic proteins and phospholipids and modulate various cellular functions including macromolecular synthesis. Dysregulation of the polyamine pathway leads to pathological conditions including cancer, inflammation, stroke, renal failure and diabetes. Increase in polyamines and polyamine synthesis enzymes is often associated with tumor growth, and urinary and plasma contents of polyamines and their metabolites have been investigated as diagnostic markers for cancers. Of these, diacetylated derivatives of spermidine and spermine are elevated in the urine of cancer patients and present potential markers for early detection. Enhanced catabolism of cellular polyamines by polyamine oxidases (PAO), spermine oxidase (SMO) or acetylpolyamine oxidase (AcPAO), increases cellular oxidative stress and generates hydrogen peroxide and a reactive toxic metabolite, acrolein, which covalently incorporates into lysine residues of cellular proteins. Levels of protein-conjuagated acrolein (PC-Acro) and polyamine oxidizing enzymes were increased in the locus of brain infarction and in plasma in a mouse model of stroke and also in the plasma of stroke patients. When the combined measurements of PC-Acro, interleukin 6 (IL-6), and C-reactive protein (CRP) were evaluated, even silent brain infarction (SBI) was detected with high sensitivity and specificity. Considering that there are no reliable biochemical markers for early stage of stroke, PC-Acro and PAOs present promising markers. Thus the polyamine metabolites in plasma or urine provide useful tools in early diagnosis of cancer and stroke.

Water sorption of CH3- and CF3-Bis-GMA based resins with additives

OBJECTIVES: To evaluate the effect of additives on the water sorption characteristics of Bis-GMA based copolymers and composites containing TEGDMA, CH3Bis-GMA or CF3Bis-GMA. MATERIAL AND METHODS: Fifteen experimental copolymers and corresponding composites were prepared combining Bis-GMA and TEGDMA, CH3Bis-GMA or CF3Bis-GMA, with aldehyde or diketone (24 and 32 mol%) totaling 30 groups. For composites, barium aluminosilicate glass and pyrogenic silica was added to comonomer mixtures. Photopolymerization was effected by 0.2 wt% each of camphorquinone and N,N-dimethyl-p-toluidine. Specimen densities in dry and water saturated conditions were obtained by Archimedes' method. Water sorption and desorption were evaluated in a desorption-sorption-desorption cycle. Water uptake (%WU), water desorption (%WD), equilibrium solubility (ES; µg/mm³), swelling (f) and volume increase (%V) were calculated using appropriate equations. RESULTS: All resins with additives had increased %WU and ES. TEGDMA-containing systems presented higher %WU, %WD, ES, f and %V values, followed by resins based on CH3Bis-GMA and CF3Bis-GMA. CONCLUSIONS: Aldehyde and diketone led to increases in the water sorption characteristics of experimental resins.

Insulin-like signaling pathway functions in integrative response to an olfactory and a gustatory stimuli in Caenorhabditis elegans

Animals integrate various environmental stimuli within the nervous system to generate proper behavioral responses. However, the underlying neural circuits and molecular mechanisms are largely unknown. The insulin-like signaling pathway is known to regulate dauer formation, fat metabolism, and longevity in Caenorhabditis elegans (C. Elegans). Here, we show that this highly conserved signaling pathway also functions in the integrative response to an olfactory diacetyl and a gustatory Cu(2+) stimuli. Worms of wild-type N2 Bristol displayed a strong avoidance to the Cu(2+) barrier in the migration pathway to the attractive diacetyl. Mutants of daf-2 (insulin receptor), daf-18 (PTEN lipid phosphatase), pdk-1 (phosphoinositide-dependent kinase), akt-1/-2 (Akt/PKB kinase) and sgk-1 (serum- and glucocorticoid-inducible kinase) show severe defects in the elusion from the Cu(2+). Mutations in DAF-16, a forkhead-type transcriptional factor, suppress the integrative defects of daf-2 and akt-1/-2 mutants. We further report that neither cGMP nor TGFβ pathways, two other dauer formation regulators, likely plays a role in the integrative learning. These results suggest that the insulin-like signaling pathway constitutes an essential component for sensory integration and decision-making behavior plasticity.

Construction of a new brewing yeast strain with secretive alpha-amylase activity and reduced diacetyl production / 生物工程学报

Saccharomycopsis fibuligera possesses high alpha-amylase and glucoamylase activities that enable it to utilize raw starch as a carbon source. A expression cassette containing the promoter sequence of 3-phosphogylycerate kinase gene (PGK1p), the alpha factor signal sequence from Saccharomyces cerevisiae and the alpha-amylase coding sequence of S. fibuligera was constructed. The alpha-amylase expression cassette was inserted in the ILV2 locus of industrial brewer's yeast strain YSF-5 encoding alpha-acetolactate synthase (AHAS) by homologous recombination. The transformed yeast strain was selected on the media with starch as the sole carbon source and verified by PCR. The transformant exhibited secretive alpha-amylase activity, low AHAS activity and reduced diacetyl production. Effects of temperature, pH, and metal ions on the activity of the alpha-amylase expressed by the transformant were examined. The fermentation performance of host strain YSF-5 and the transformant was also examined.

Genetically modified industrial brewing yeast with high-glutathione and low-diacetyl production / 生物工程学报

Recombinant plasmid pICG was constructed by replacing the internal fragment of a-acetohydroxyacid synthase (AHAS) gene (ILV2) with a copy of gamma-glutamylcysteine synthetase gene (GSH1) and copper chelatin gene (CUP1) from the industrial brewing yeast strain YSF31. YSF31 was transformed with plasmid pICG linearized by Kpn I and Pst I. A recombinant strain with high-glutathione and low-diacetyl production was selected. The results of fermentation in 100-L bioreactor showed that the lagering time of beer produced for recombinant strain T2 was shortened by 3 days and the shelf life of the beer was prolonged about 50%. It may be more acceptable for the commercial application, as it does not contain foreign DNA.

Non-specific effect of myosin inhibitor BDM on skeletal muscle contractile function / 中国应用生理学杂志

<p><b>AIM</b>In order to elucidate the underlying mechanism of depressed maximal isometric twitch tension normalized by cross sectional area of muscle strip in unloaded soleus.</p><p><b>METHODS</b>The soleus and extensor digitorum longus (EDL) muscle strips were perfused in vitro and treated by 2,3-Butanedione monoxime (BDM).</p><p><b>RESULTS</b>The BDM decreased Pt of soleus and EDL in a concentration-dependent manner. The Pt could restored completely to normal level after washing out BDM. The isometric twitch duration was not altered during 1 mmol/L BDM of perfusion, but was shortened at 10 mmol/L dose. The time from maximal to half Pt in EDL was shorter than that in soleus during 10 mmol/L BDM of perfusion. The inhibitory effects of BDM on myosin ATPase activity were higher in EDL than in soleus. The inhibitory extent of BDM on myosin ATPase activity of soleus and EDL was lower than that on Pt.</p><p><b>CONCLUSION</b>These results suggest that reduction in cross-bridge function of skeletal muscle may be one of reasons induced a decrease in its Pt. BDM is not a specific inhibitor on myosin ATPase activity and can affect multiple parts of excitation-contraction coupling in skeletal muscle.</p>

Genetic organization and expression of citrate permease in lactic acid bacteria

Citrate is present in many natural substrates, such as milk, vegetables and fruits, and its metabolism by lactic acid bacteria (LAB) plays an important role in food fermentation. The industrial importance of LAB stems mainly from their ability to convert carbohydrates into lactic acid and, in some species, like Lactococcus lactis and Leuconostoc mesenteroides, to produce C4 flavor compounds (diacetyl, acetoin) through citrate metabolism. Three types of genetic organization and gene locations, involving citrate metabolism, have been found in LAB. Citrate uptake is mediated by a citrate permease, which leads to a membrane potential upon electrogenic exchange of divalent citrate and monovalent lactate. The internal citrate is cleaved into acetate and oxaloacetate by a citrate lyase, and oxaloacetate is decarboxylated into pyruvate by an oxaloacetate decarboxylase, yielding a pH gradient through the consumption of scalar protons.

Contenido de diacetilo en queso venezolano tipo palmita / Diacetyl content in venezuelan palmita type cheese

Veinte muestras de queso venezolano tipo Palmita, proveniente de dos expendios comerciales en la ciudad de Maracaibo, fueron analizadas en su contenido de diacetilo durante un lapso experimental de cinco semanas. Las muestras de queso fueron sometidas a destilación para recuperar el diacetilo formado. A 10 ml del destilado de cada queso, se le adicionó 0,5 ml de o-fenilendiamina y 2 ml de HCI para obtener valores de absorbancia del diacetilo a 340 nm, en un espectrofotómetro UV perkin-Elmer, lambda 3-ß. La concentración de diacetilo en cada muestra de queso se obtuvo a través de una curva estándar. Los resultados revelaron diferencias significativas (P<0,05) entre los quesos analizados. Las concentraciones de diacetilo variaron entre niveles de 0,92 y 6,92 ppm, los cuales están dentro del rango encontrado en los quesos Emmental, Cheddar y Parmesano

Synthesis of d- and l-Form of 99mTc-HMPAO, and Comparison of Brain Uptake / 대한핵의학회잡지

PURPOSE: 99mTc-HMPAO is a radiopharmaceutical for imaging cerebral blood flow. HMPAO (RR, SS)-4,8- diaza-3,6,6,9-tetramethylundecan-2,10- dione bisoxime) has three stereoismers such as, meso-, d-, and l-HMPAO. Techentium complexes of meso-HMPAO and d,l-HMPAO are known to have different in vivo brain uptakes. In this study, enantiomers of HMPAO (d-HMPAO and l-HMPAO) were separated from d,l-HMPAO. These enantiomers were labeled with 99mTc and the biodistribution studies were performed in mice. MATERIALS AND METHODS: An intermediate imine product was produced from 2,3-butanedione monooxime and 2,2-dimethyl- 1,3-propanediamine (54% yield) and was reduced into a mixture of three isomers (35% yield). The meso-isomer was separated from d,l-mixture by repeated fractional crystallization (11% yield). The d- and l-enantiomers were subsequently separated by co-crystallization with optical isomers of tartaric acid (25% and 5% yield, respectively). Each enantiomeric HMPAO was labeled with 99mTc by reacting with SnCl2 2H2O and 99mTc-pertechnetate. Biodistribution study was performed 1 hr after tail vein injection to ICR mice. RESULTS: Radiochemical purities of each compound were over 80%. In biodistribution study, the brain uptakes of d,l- d- and l-form were 1.34, 1.12 and 1.67% ID/g, respectively. In case of l-Isomer the brain uptake was higher (1.5 fold) than d-isomer. CONCLUSION: We successfully purified each enantiomeric HMPAO. In biodistribution study of stereoismers of 99mTc-HMPAO in mice, l-HMPAO may show better brain image than d,l-HMPAO which was supplied in a commercial kit.

The Effects of Excitation-Contraction Uncouplers on the Dynamics of Ventricular Fibrillation in Isolated Swine Right Ventricles

BACKGROUND: Whether or not the excitation-contraction (EC) uncoupler, diacetyl monoxime (DAM) and cytochalacin D (Cyto D) alter the ventricular fibrillation activation patterns is unclear. METHODS: We recorded single cell action potentials and performed optical mapping in isolated perfused swine right ventricles at different concentrations of DAM and cyto D during ventricular fibrillation and dynamic pacing. RESULTS: Increasing concentration of DAM results in progressively shortened action potential duration measured to 90% repolarization (APD90), reduced slope of the action potential duration restitution(APDR) curve, decreased Kolmogorov-Sinai entropy, and reduced number of ventricular fibrillation wavefronts. In all right ventricles, 15 to 20 mmol/l DAM converted ventricular fibrillation to ventricular tachycardia. The ventricular fibrillation could be reinduced after the DAM was washed out. In comparison, cyto D (10 to 40 mol/l) has no effects on APDR curve or the dynamics of ventricular fibrillation. The effects of DAM on ventricular fibrillation are associated with reduced number of wavefronts and dynamic complexities in ventricular fibrillation. CONCLUSION: These results are compatible with Restitution Hypothesis of ventricular fibrillation and suggest that DAM may be unsuitable as an EC uncoupler for optical mapping studies of ventricular fibrillation in the swine right ventricles.

Diacetyl formation by lactic bacteria

Los aromas o sustancias aromatizantes son compuestos intermediarios empleados ampliamente en la industria alimentaria. Estos aditivos pueden ser producidos por síntesis química o naturalmente por fermentación. Ultimamente los más solicitados por los industriales debido a la tendencia que tienen los consumidores hacia los productos naturales son los producidos por fermentación. El diacetilo es uno de los componentes primordiales del aroma a mantequilla, aunque también deben estar presentes otros compuestos como la acetoína, el acetaldehído y el 2,3-butanodiol en menor proporción. La mezcla de todos estos compuestos en proporciones adecuadas es lo que origina el aroma característico a mantequilla. El diacetilo, así como los compuestos de acompañamiento son producidos por la fermentación de las bacterias lácticas. La ruta metabólica del piruvato. En este caso la biosíntesis del diacetilo depende de la presencia de citrato en el medio. Otra ruta alternativa es a partir del acetaldehído, en esta ruta parece que no interviene el citrato. En este trabajo se hace una revisión de los mecanismos de formación del diacetilo por bacterias lácticas; así como de los factores más importantes que influyen en la biosíntesis de este metabolito