Changes of Exponential Growth Rates in Relation to Differentiation of Geotrichum candidum in Submerged Culture

Growth and differentiation of the imperfect fungus Geotrichum candidum were followed in submerged cultures containing a simple synthetic glucose salt medium. Uptake of glucose, ammonium and oxygen from the medium were measured during the entire growth perod. In 0.1% glucose the fungus grows with one exponential growth phase until all the glucose has been consumed. The arthrospores are formed in the stationary phase. In 0.5% glucose the growth curve has two exponential growth phases, one with a doubling time of 1.8 h and a second one with a doubling time of 4.9 h. The second exponential growth phase, which starts when less than 15% of the glucose and less than 30% of the ammonium have been consumed, is shown to be the sporulation phase. During this growth phase the oxygen saturation in the culture remained constant at about 50%.     

产木聚糖酶白地霉培养特性及部分纯化的酶学特性

本文对白地霉Ref1的培养特性、产酶条件和酶学特性进行了初步研究。结果表明:该菌为低温型菌株,其最佳生长条件为pH6、20℃和酵母膏作为氮源;最佳产酶条件为pH3-7、15℃及以酵母膏氮源;条件优化后产酶可达118.7U/mL,可溶蛋白含量可达到60μg/mL,酶溶液的比活可达到1250U/mg蛋白质;该木聚糖酶的最适反应温度和pH分别为50℃和5,金属离子Mg2+、Na+和8mmol/L的Fe2+、Cu2+、Zn2+等对木聚糖酶的活性有抑制作用,而Ca2+、4mmol/L的Fe2+、Cu2+、Zn2+和8mmol/L的Mn2+等对该酶反应则有促进作用;该木聚糖酶在保温2h后在15-40℃范围内能保持80%以上的酶活性,在50℃时能保持68%的酶活性;用lineweaver-Burk作图法(双倒数作图法)求得该酶的最大反应速度Vmax和Km值分别为163.38mmol/mg/min和0.75mg/mL。     

Chiral synthesis of secondary alcohols using Geotrichum candidum

Chiral synthesis of secondary alcohols of both the (S)- and (R)-enantiomer with extremely high enantioselectivities (up to >99% ee) using a biocatalyst, Geotrichum candidum, is reviewed. Resting cell and dried-cell preparation using acetone were applied to oxidation, reduction, and deracemization reactions. Many methods to improve the reactivity and enantioselectivity of the reactions were developed. For example, additives such as secondary alcohols and hydrophobic resin (Amberlite XAD) were used in nonaqueous reaction media such as organic and supercritical solvents as well as in aqueous ones. As a result, optically pure alcohols of both enantiomers were synthesized on a gram scale.     

二氧化碳安乐死在实验动物中的应用与最新进展

本文概述了二氧化碳（CO2）安乐死法的作用机制、CO2使用浓度、应用范围和操作注意事项,并讨论了该方法的动物福利、设备改进等问题。     

Growth of Geotrichum candidum and Penicillium camemberti Cultivated on Liquid Media Correlated with Ammonia and Methanethiol Emission

The growth of Geotrichum candidum and Penicillium camemberti plays an important role in the ripening of Camembert‐type cheeses, but the monitoring of the corresponding kinetics for fungal cocultures on solid media appears difficult. Continuous and non‐intrusive methods to characterize the growth of both species (like the monitoring of the emissions of ammonia and volatile sulphur compounds) may be highly relevant, under the condition that such emissions could be correlated with growth. This would be easier to investigate in submerged culture, since total biomass concentration is known to vary in proportion to broth turbidity. For this reason, growth kinetics, ammonia and flavour gas emission of both Geotrichum candidum and Penicillium camemberti grown separately in submerged cultures under the conditions of low aeration rate and uncontrolled pH were continuously recorded.In the basal medium (peptone+lactate supplemented with both glutamic acid and methionine [1 g/l]each), no significant gas emission was observed during the growth of both fungi. Ammonia and sulphur gas emissions by G. candidum were a little stimulated by supplementing the basal medium with trace elements, and, at a larger extent, by the addition of inorganic phosphate: Such a gaseous emission took place at the end of the growth phase of G. candidum. Irrespective of the basal medium supplementation, no significant emission ofammonia and sulphur gas was observed during the growth of P. camemberti. For the media and strains used, ammonia and volatile sulphur compounds emissions unequivocally showed the growth of Geotrichum candidum.     

腹腔镜术中二氧化碳异常弥散所致并发症

气腹是腹腔镜手术顺利进行的重要条件,二氧化碳(CO2)是气腹时最常用的气体。然而,腹腔镜手术除可引起开放式手术类似的并发症外,尚可引起腹腔镜技术相关的并发症。临床医生应当充分重视并及时处理各种并发症。这些并发症中以CO2异常弥散引起的并发症较为常见,且症状较严重。该类并发症主要包括CO2气体栓塞、气肿和气胸等,本文将就此进行综述。     

Potential of pure and mixed cultures of Cladosporium cladosporioides and Geotrichum candidum for application in bioremediation and detergent industry

The effect of ethoxylated oleyl–cetyl alcohol (Henkel, “Merima”, Serbia) on the growth and metabolic activity of Cladosporium cladosporioides, Geotrichum candidum and their mixed culture was in the focus of this paper. The cultures were grown in Czapek-Dox liquid nutrient medium with the addition of 0.5% pollutant and without it. The physico-chemical and biochemical changes of pH, the total biomass dry weight, the quantity of free and total organic acids, proteolytic activity and the quality of carbohydrates were evaluated from 4th to 19th day of fungal growth. The pollutant caused an inhibitory effect on biomass dry weight of C. cladosporioides and G. candidum for 10.36% and 4.65% respectively, and stimulatory effect on biomass of mixed culture for 3.80%. The pollutant had influence on the decrease in pH value of the media in the phase of culture growth, and pH changes were correlated with the amount of excreted total organic acids. The highest quantity of free and total organic acids was noted in media with pollutant of mixed culture and C. cladosporioides, respectively. The alkaline protease activities of C. cladosporioides, G. candidum and mixed culture were enhanced by addition of pollutant for 56.88%, 55.84% and 30.94% respectively. The obtained results indicate the potential of both pure and mixed cultures in mycoremediation environment contaminated by alcohol ethoxylated and detergent industry.     

Model-Based Analysis of Mechanisms Responsible for Sleep-Induced Carbon Dioxide Differences

This work describes a comprehensive mathematical model of the human respiratory control system which incorporates the central mechanisms for predicting sleep-induced changes in chemical regulation of ventilation. The model integrates four individual compartments for gas storage and exchange, namely alveolar air, pulmonary blood, tissue capillary blood, body tissues, and gas transport between them. An essential mechanism in the carbon dioxide transport is its dissociation into bicarbonate and acid, where a buffering mechanism through hemoglobin is used to prevent harmfully low pH levels. In the current model, we assume high oxygen levels and consider intracellular hydrogen ion concentration as the principal respiratory control variable. The resulting system of delayed differential equations is solved numerically. With an appropriate choice of key parameters, such as velocity of blood flow and gain of a non-linear controller function, the model provides steady-state results consistent with our experimental observations measured in subjects across sleep onset. Dynamic predictions from the model give new insights into the behaviour of the system in subjects with different buffering capacities and suggest novel hypotheses for future experimental and clinical studies.     

二氧化碳激光治疗联合5-氟尿嘧啶对扁平疣的疗效分析

目的:探讨二氧化碳激光治疗联合5-氟尿嘧啶对扁平疣的疗效。方法:选择2012年2月~2015年9月在我院进行诊治的扁平疣患者121例,男62例,女59例,其中观察组61例给予二氧化碳激光联合5-氟尿嘧啶注射液治疗,对照组60例给予二氧化碳激光治疗,比较两组的疗效,T淋巴细胞亚群,复发率及不良反应。结果:观察组总有效率为98.36%,明显高于对照组91.67%(P0.05);经治疗后,两组治疗后的CD4+、CD8+和CD4+/CD8+均较治疗前有显著性差异(P0.05);与对照组相比,观察组治疗后的CD4+和CD4+/CD8+明显升高,CD8+明显降低,差异均有统计学意义(P0.05);观察组的复发率为5.88%,明显低于对照组的15.00%(P0.05);两组的不良反应发生情况无明显差异(P0.05)。结论:二氧化碳激光治疗联合5-氟尿嘧啶对扁平疣疗效显著,可明显提高患者免疫功能,降低扁平疣的复发率,值得临床应用推广。     

慢性间断性缺氧伴二氧化碳潴留小鼠模型的建立

目的建立慢性间断性缺氧伴二氧化碳潴留（chronic intermittent hypoxia with carbon dioxide retention,CIH-CR）小鼠模型。方法选取雄性昆明小鼠22只,随机分为常氧组（normal control group,NC）和CIH-CR组,每组11只。CIH-CR组小鼠每天CIH-CR处理8 h,共4周,实验期间监测箱内O2和CO2浓度及小鼠尾部末端血氧饱和度（SO2）。实验终点测定右室肥厚指数并观察心、肺、肾、脑组织病理改变。结果 CIH-CR组箱内O2浓度、CO2浓度和小鼠尾部末端SO2随实验仓的关闭和开启出现周期性的变化;与NC组相比CIH-CR组右心室明显肥大（P〈0.01）;小鼠心、肺、肾和脑组织均出现明显缺氧改变。结论成功建立了CIH-CR小鼠模型。     

常用功率密度CO2激光治疗尖锐湿疣时烟尘中HPV DNA的检测

目的 :了解临床常用功率密度的 CO2 激光治疗尖锐湿疣术中烟尘是否含有 HPVDNA。方法 :选择皮损较多的尖锐湿疣 ,病程在 6个月以内的患者作为研究对象 ,分别用 5 W、1 0 W、1 5 W对应功率密度下的 CO2 激光汽化在体疣体组织 ,离光斑 5 cm或 5 0 cm处用吸尘器抽吸烟尘于 PBS中 ,经固定后观察烟尘的细胞形态学 ,并用 HPV通用型引物作 PCR检测烟尘是否含有 HPV-DNA。结果 :三种功率密度的烟尘主要由炭化颗粒组成 ,其中含有少量破碎的上皮细胞及形态完整和不完整的单个表皮细胞或细胞团 ;PCR检测 CO2 激光在 5 W、1 0 W、1 5 W对应功率密度下治疗时的烟尘 ,HPV DNA阳性数分别为 :1 /1 3、3 /9、3 /1 5例。结论 :CO2激光常用功率密度治疗尖锐湿疣时 ,烟尘中有 HPV DNA存在 ,为防其对人体造成的危害 ,需要及时抽排烟尘。     

Carbon Dioxide Exchange of Spring-wheat in Relation to Age and Photon-flux Density at Different Growth Temperatures

CO₂-exchange rates (CER) of the sixth and the flag leaves oftwo spring-wheat varieties, Kolibri and Famos, were comparedusing an open-circuit infrared gas analysing system. Measurementswere repeated every two weeks starting when leaf blades werefully expanded. Single plants were grown in a controlled environmenthaving a photopuiod of 15 h and a day/night temperature of 24/19°C(H), 18/13 °C (M), and 12/7 °C (L) respectively untilapprox. 2 weeks after anthesis and at 18/13 °C until maturity.The photosynthetic photon-flux density (PPFD) at the top ofthe plants was 500 µE m^–2 sec^–1. During themeasurements PPFD was gradually reduced from 2000 to 0 µEm^–2 sec^–1 whereas the temperature was maintainedat the respctive growth-temperatures during the light period.The CER of the sixth leaf declined fairly similarly for bothvarieties, except for Kolibri where a faster decline was observedduring the first two weeks after full leaf expansion. The CERof the flag leaf declined more slowly than that of the sixthleaf. With the flag leaf of Famos, the decline was nearly linear,whereas with Kolibri it was very slow during the first few weeksbut rapid as the leaves further senesced. This pattern becamemore pronounced as the growth temperature decreased. The declinein relation to leaf age was much smaller at low PPFD than athigh PPFD during the same period. At full leaf expansion Kolibrireached higher maximum CER than Famos except at H. As the PPFDwas reduced the difference became smaller and at very low PPFDsuch as 50 µE m^–2 sec^–1 was reversed for thesixth leaf. Under optimum growth conditions maximum values ofCER were greater than 50mg CO₂ dm^–2h^–1 and PPFDfor light saturation was close to 2000 µE m^–2 sec^–1.A comparison between the actual CER and a fitted curve widelyused, PN=(a+b/l)^–1–DR, showed that the goodnessof fit strongly depends on cultivar, treatment and leaf ageas well as on the number and the level of PPFD from which datafor calculations are taken. Triticum aestivum, L., wheat, photosynthesis, photon-flux density, light response, carbon, dioxide exchange     

The Analysis of Correlative Growth in the Etiolated Oat Seedling in Relation to Carbon Dioxide and Nutrient Supply

To overcome the reduced extension growth of the coleoptile whichoccurs when oats are grown in air enriched with 5 per cent.CO¹, plants have been provided with nutrients via the roots.2 per cent, sucrose, glucose or mannitol so applied furtherpromoted the mesocotyl and further depressed the coleoptile.Root growth was also depressed. To induce promotion of coleoptile growth by externally appliedsucrose, seedlings were heated in darkness at 40° C. for3 hours so restricting selectively the growth of the mesocotyl.Promotion of the coleoptile, however, was not observed. Application of mixed Na and K nitrates occasioned an immediategrowth promotion of doleoptile and leaves in both the presenceand absence of CO², and also a.much less pronounced promotionof the mesocotyl in CO²; there was no effect in air. This enhancedgrowth of the coleoptile and leaves was coupled with a correspondinglygreater dry weight and also with an increased outflow of reservesfrom the endosperm into the plumule. Thus, while externally applied sugars seemed not to reach thecoleoptile, those made available from the endosperm as a resultof improved nitrogen supply were rapidly translocated to it.Simultaneous provision to the roots of nitrate and sucrose didnot improve the absorption and translocation of sugar. An analysis of covariance has been computed using the mesocotyland coleoptile length data together with the outflow from theendosperm and the conclusions so derived are discussed in relationto the problem of growth integration in etiolated oat seedlings.     

Extracellular and cell-bound lipase activity in relation to growth of Geotrichum candidum

Summary The imperfect fungus Geotrichum candidum produced extracellular lipase in a basic peptone-salt medium. By adding olive oil or Tween 80 to the basic medium the lipase yields could be enhanced and the maximal yields were found with Tween 80, which resulted in a sixfold increase in extracellular lipase activity as compared with basic medium. During the early phase of growth in medium with olive oil the proportion of cell-bound activity was higher than that of extracellular activity, and a delay in the secretion of extracellular lipase was found. The proportion of cell-bound activity from growth in basic medium and in basic medium with Tween 80 was lower than that of extracellular activity during the entire growth phase. Analyses by polyacrylamide gel electrophoresis showed that the lipase activity from growth in all three media could be ascribed to equivalent protein bands at 57 000 and 61 000 daltons. Immunodiffusion showed that the cell-bound preparation contained lipase that was immunologically identical with purified extracellular lipase from G. candidum.     

Temporal accumulation of mannitol and arabitol in Geotrichum candidum

The temporal depletion and accumulation of polyols were investigated in the fungus Geotrichum candidum. The major intracellular polyols were tentatively identified by paper chromatography as mannitol and arabitol. Inositol was also present in small quantities, and trehalose was also detected in appreciable concentrations.Germination and vegetative growth depended on the type and concentration of the sole exogenous carbon source. Mannitol occurred in arthrospores at 9.4% of the dry weight after several days growth in 2% (w/v) glucose solid medium, and became depleted during germination and vegetative growth in liquid medium containing 2% (w/v) glucose, 2% (w/v) sodium acetate or 25% (w/v) glucose as sole carbon source. This hexitol latter accumulated during arthrosporulation. The depletion and accumulation of ethanol-soluble carbohydrate believed to be primarily trehalose was temporally similar to that of mannitol. Arabitol accumulated intracellularly during germination and vegetative growth in sodium acetate medium and 25% glucose medium. This pentitol was not detected intracellularly at any culture age during growth in 2% glucose medium.Prolonged incubation of the culture in 25% glucose medium after stationary phase was reached resulted in the gradual disappearance of arabitol from the arthrospores simultaneously with an increase in intracellular mannitol. In comparison, ethanol-soluble carbohydrate did not change with prolonged incubation in this medium.     

A Mathematical Model for Vegetative Growth of Bacillus Thuringiensis

A structured but unsegregated model was developed for the vegetative growth of Bacillus thuringiensis (Bt) cells. This model included cell growth, limiting‐substrate consumption, production and consumption of acetic acid, and production of poly‐β‐hydroxy butyric acid. The parameter estimation and model validation were conducted using data from carbon‐limited batch experiments. The model successfully predicted batch behavior of biomass and glucose concentrations.     

Direct Observation of Spin-Trapped Carbon Dioxide Radicals in Hepatocytes Exposed to Carbon Tetrachloride

Carbon dioxide radical adducts of the spin trapping agent, α-phenyl N-t-butyl nitrone (PBN), have been observed to occur in the urine and bile of rats exposed to carbon tetrachloride as well as in perfusates of liver in which the perfusion medium contained carbon tetrachloride (Connor er al., J. Biol. Chem., 261, 4542, (1986)). The carbon dioxide adduct was proven to be derived from CCI, by use of 13-C-labelled compound. These adducts were not observed in the liver itself suggesting that they might be rapidly secreted from the liver. However, using isolated hepatocytes, we have demonstrated that the carbon dioxide radical adduct can be observed directly in the liver cells as it is formed. Since this water-soluble adduct cannot be extracted by non-aqueous solvents such as chloroform or toluene, its formation in liver in vivo or in perfused livers was not detected. Lowering the oxygen tension in the system diminished the intensity of production of the carbon dioxide adduct, consistent with the adduct being produced as a result of ·OOCCl₃ generation. It is not clear the extent to which this adduct is formed as a result of the ·CO₂ radical or is produced by metabolic oxidation of the trichloromethyl radical adduct of PBN per se to the carbon dioxide radical adduct. The intensity of the signal of the carbon dioxide radical adduct suggests that adduct conversion may be the route of formation since it seems unlikely that a sufficient amount of the halocarbon could be metabolized to ·COCl or ·CO₂ radicals to generate a signal of the magnitude involved. The ·CO₂ adduct is readily observed in intact hepatocytes, but the ·CCl₃ adduct is not (although we know the ·CCl₃ adduct has been produced in these cells), indicating that the ·CO₂ adduct is present in considerable abundance compared to the ·CCl₃ adduct.     

Altered Circadian Relationship Between Serum Nitric Oxide, Carbon Dioxide, and Uric Acid in Multiple Sclerosis

The free radical nitric oxide (NO^·) is involved in a variety of diverse biological processes from acting as a vasodilator in the cardiovascular system to being the rate-limiting component in the production of peroxynitrite (ONOO^-), a contributor to neurodegenerative disorders such as multiple sclerosis (MS). Uric acid (UA), the end product of purine metabolism in humans and a selective inhibitor of toxic reactions attributed to radicals formed by the interaction of ONOO^- and CO₂, is generally low in MS patients. We investigated the relationship between serum ONOO^-, CO₂, and UA in MS patients and normal controls by comparing the circadian characteristics of the NO^· metabolites nitrite/nitrate (NO), CO₂, and UA. In this preliminary study, we found the functional relationship ascribed to the circadian timing of the peak and trough levels of NO, CO₂, and UA in healthy subjects to be clearly altered in MS patients. These findings suggest that alterations in the temporal relationship between the 24 h pattern in serum ONOO^- formation and UA may either contribute to or reflect the disease processes in MS.     

Altered Circadian Relationship Between Serum Nitric Oxide,Carbon Dioxide,and Uric Acid in Multiple Sclerosis

The free radical nitric oxide (NO^·) is involved in a variety of diverse biological processes from acting as a vasodilator in the cardiovascular system to being the rate-limiting component in the production of peroxynitrite (ONOO^?), a contributor to neurodegenerative disorders such as multiple sclerosis (MS). Uric acid (UA), the end product of purine metabolism in humans and a selective inhibitor of toxic reactions attributed to radicals formed by the interaction of ONOO^? and CO₂, is generally low in MS patients. We investigated the relationship between serum ONOO^?, CO₂, and UA in MS patients and normal controls by comparing the circadian characteristics of the NO^· metabolites nitrite/nitrate (NO), CO₂, and UA. In this preliminary study, we found the functional relationship ascribed to the circadian timing of the peak and trough levels of NO, CO₂, and UA in healthy subjects to be clearly altered in MS patients. These findings suggest that alterations in the temporal relationship between the 24 h pattern in serum ONOO^? formation and UA may either contribute to or reflect the disease processes in MS.