[Phrenic nerve stimulation protects against mechanical ventilation-induced diaphragmatic dysfunction through myogenic regulatory factors]

Objective: To explore the protective effect of electrical stimulation of phrenic nerve on diaphragmatic function during mechanical ventilation. Methods: Forty healthy adult SD rats were randomly divided into 5 groups: blank control group (BC), spontaneous breathing group (SB), electrical stimulation group (ES), mechanical ventilation group (MV), and electrical stimulation and mechanical ventilation group (MS). The rats in each group were treated for 18 h except for the BC group. After treatment, the diaphragm muscle tissue was obtained and the diaphragm contractility including peak-to-peak value(Vpp) and maximum rate of contraction(+ dT/dt max) were measured. Expression of MyoD and myogenin were detected. Results: Except for the ES and the MS groups, there was a significant difference for peak-to-peak value (Vpp) between each 2 groups (P<0.05). Expression levels of MyoD in treatment groups were also significantly different (P<0.05). Expressions of MS(Q-PCR 2(-ΔΔCt) value: 11.66±2.80) and MV(Q-PCR 2(-ΔΔCt) value: 40.89±24.71) in the treatment group were significantly different (P<0.05). The expression of myogenin in the MS and the MV groups were significantly different from those of the BC group(P<0.05), however there was no significant difference between the MS(Q-PCR 2(-ΔΔCt) value: 2.58±2.75) and the MV group(Q-PCR 2(-ΔΔCt) value: 1.63±0.71). Conclusions: Electrical stimulation of the phrenic nerve can change the expression level of MyoD and myogenin to offset mechanical ventilation induced diaphragmatic function damage, and therefore plays a protective effect on the diaphragm.

[Value of heart rate as an optimum index in evaluating physical labor intensity]

Objective: To investigate the possibility of heart rate as an optimum index for evaluating physical labor intensity. Methods: From September to October, 2015, a total of 111 male young adults were selected as study subjects. A cycle ergometer was used for exercise at different intensities (20, 40, 60, 80, 100, 120, 140, 160, and 180 W) , and the exercise at each intensity lasted for 6 minutes. The subjects wore the K4b2 portable cardiopulmonary function testing instrument for the real-time monitoring of heart rate (HR) , pulmonary ventilation volume (Ve) , oxygen consumption (VO(2)) , and energy metabolic rate (E) . The origin software was used for correlation and regression analyses of HR, Ve, VO(2), and E collected at different intensities to establish Ve-HR, VO(2)-HR, and E-HR regression equations. Results: At different intensities, HR was positively correlated with Ve, VO(2), and E (r=0.8985, 0.8733, and 0.8973, all P<0.01) . There was a significant difference in the R(2) value of Ve-HR, VO(2)-HR, and E-HR regression equations (R(2)=0.8070, 0.7625, and 0.8049, all P <0.01) . The validation results showed that there was no significant difference between the calculated values and the measured ones (P>0.05) . Conclusion: HR can replace Ve, VO(2), and E and be used as an optimum index for evaluating physical labor intensity.

Cultivation of the carotenoid-hyperproducing mutant 2A2N of the red yeast Xanthophyllomyces dendrorhous (Phaffia rhodozyma) with molasses

The carotenoid-hyperproducing mutant 2A2N of the yeast Xanthophyllomyces dendrorhous (Phaffia rhodozyma) was cultivated using sugar beet blackstrap molasses. This molasses was composed of 70% (w/v) total solid and 50% (w/v) total sugar. Biomass yield (biomass/carbohydrate) significantly decreased at >5% (v/v) molasses. Atomic emission spectrometry revealed that Na and P were the limiting nutrients when molasses was used. Molasses (5%, v/v) containing urea (30 g/l molasses) and sodium phosphate (NaH2PO4, 5 g/l molasses) was formulated for biomass production by the mutant. The optimal pH for carotenoid production was 4.9 during the growth phase and 2.6-3.5 during the stationary phase. The three main sugars in molasses (sucrose, glucose, and fructose) were assimilated by the mutant but fructose was consumed slowly. When the formulated medium with pH 4.5-5.5 was used, the maximal biomass yield was 36 g/l (0.18 g of yeast l(-1)h(-1) and 40 mg of carotenoid l(-1)) in fed-batch pilot-scale 100-l cultivation.

Redirection of carbon flux to lysine in a recombinant of Corynebacterium lactofermentum ATCC 21799 by limited supply of pantothenate

To increase carbon flux to lysine, minimized production of amino acids that are biosynthetically related to lysine, for example, isoleucine and valine, is required. By limiting the supply of pantothenate, the precursor of coenzyme A, the carbon flux was redirected from isoleucine and valine to lysine in the recombinant of Corynebacterium lactofermentum ATCC 21799 containing the plasmid pGC77. The pGC77 contains hom(dr), thrB, and ilvA encoding feedback-deregulated homoserine dehydrogenase, homoserine kinase, and threonine dehydratase, respectively. At 250 microM of isopropyl-beta-d-thiogalactopyranoside, the recombinant (pGC77) produced lysine, valine, and isoleucine. Limiting the supply of pantothenate from 300 microg/l to 30 microg/l resulted in an increase in lysine (from 4.5 to 6.4 g/l) and decreases in valine (from 3.1 to 1.6 g/l) and isoleucine (from 0.9 to 0.3 g/l) production. The concentration of pyruvate was higher and that of acetate lower in the pantothenate-limited culture than in the control, suggesting that the limited supply of pantothenate delayed the conversion of pyruvate to acetyl-CoA. Increased availability of pyruvate by limiting the supply of pantothenate might favor the integration of pyruvate into the lysine branch. The results of this study are useful for the production of lysine with decreased concentrations of byproducts.

Effects of yeast (Saccharomyces cerevisiae) cell components on growth performance, meat quality, and ileal mucosa development of broiler chicks

An experiment was conducted with 240, 1-d-old, male broilers to investigate the effects of Saccharomyces cerevisiae (SC) cell components on the growth performance, meat quality, and ileal mucosa development. There were 4 dietary treatments, each consisting of 6 replicates. Whole yeast (WY), SC extract (YE), and SC cell wall (CW) were added at 0.5, 0.3, and 0.3%, respectively, to the control starter and finisher diets. From 0 to 3 wk of age, a lower feed/gain ratio (P < or = 0.05) was observed with CW, whereas the WY-fed birds at 4 to 5 wk of age showed a lower feed/gain ratio compared with the control. From 0 to 5 wk of age, WY and CW gave higher BW gains than did the control. The shear force of raw drumstick decreased in the WY treatment relative to the control, and YE and CW treatments were intermediate. The shear forces in cooked breast and drumstick in treatments WY and YE decreased when compared with the control. The amount of 2-thiobarbituric acid-reactive substances (TBARS) in the breast meats of WY, YE, and CW were lower than the control at 10 d of incubation. In raw drumstick meats, TBARS values were lower in treatments WY and YE than that of the control at 6 and 10 d of incubation. At 10 d of incubation, skins from YE and CW treatments had lower TBARS values than did the control. Villus height was greater in WY and CW compared with those in control and YE. No differences were found in crypt depth among the 4 treatments. The villus height/ crypt depth ratios in WY and CW were greater than those of the control and YE. It could be concluded that dietary yeast components, such as WY or CW supplementation improved growth performance. Meat tenderness could be improved by the WY or YE. Both YE and CW had oxidation-reducing effects. Yeast cell wall may improve ileal villus development.

Metabolic redirection of carbon flow toward isoleucine by expressing a catabolic threonine dehydratase in a threonine-overproducing Corynebacterium glutamicum

Carbon destined for lysine synthesis in Corynebacterium glutamicum ATCC 21799 can be diverted toward threonine by overexpression of genes encoding a feedback-insensitive homoserine dehydrogenase (hom(dr)) and homoserine kinase (thrB). We studied the effects of introducing two different threonine dehydratase genes into this threonine-producing system to gauge their effects on isoleucine production. Co-expression of hom(dr), thrB, and ilvA, which encodes a native threonine dehydratase, caused isoleucine to accumulate to a final concentration of 2.2+/-0.2 g l(-1), five-fold more than accumulates in the wild-type strain, and approximately twice as much as accumulates in the strain expressing only hom(dr) and thrB. Comparing these data with previous results, we found that overexpression of the three genes, hom(dr), thrB, and ilvA, in C. glutamicum ATCC 21799 is no better in terms of isoleucine production than the expression of a single gene, tdcB, encoding a catabolic threonine dehydratase from Escherichia coli. Co-expression of hom(dr), thrB, and tdcB, however, caused the concentration of isoleucine to increase 20-fold compared to the wild-type strain, about four times more than the corresponding ilvA-expressing strain. In this system, the apparent yield of isoleucine production was multiplied by a factor of two [2.1 mmol (g dry cell weight)(-1)]. While the balance of excreted metabolites showed that the carbon flow in this strain was completely redirected from the lysine pathway into the isoleucine pathway, it also showed that more pyruvate was diverted into amino acid synthesis.

Correlation of plasma homocysteine and mitochondrial DNA content in peripheral blood in healthy women

Hyperhomocysteinemia is an independent risk factor of cardiovascular disease and associated with insulin resistance, although their causal relationship remains unclear. A previous report has shown that high concentration of homocysteine damages mitochondrial gene expression, function and structure. As we found recently, the mitochondrial DNA (mtDNA) contents are inversely correlated with insulin resistance parameters. Thus there is possibility that plasma total homocysteine (tHcy) level is somewhat correlated with mtDNA content. Sixty healthy women (mean age 40.3+/-20.9 yr, range 18-78 yr) were recruited to investigate the correlation of plasma tHcy level and mtDNA content in peripheral blood. A significant negative correlation was found between plasma tHcy levels and mtDNA content (r=-0.507, P<0.01). Plasma tHcy and mtDNA content have an independent effect on each other and on insulin resistance (HOMA-insulin resistance (IR) score) respectively in multiple regression model. Plasma tHcy showed positive correlations with age (r=0.407), W/H ratio (r=0.370), total cholesterol (r=0.338), LDL-cholesterol (r=0.317) and insulin resistance (HOMA-IR score) (r=0.261); and a negative correlation with folate (r=-0.273). MtDNA content showed negative correlations with age (r=-0.407), BMI (r=-0.440), W/H ratio (r=-0.659), SBP (r=-0.350), total cholesterol (r=-0.340), triglyceride (r=-0.376), LDL-cholesterol (r=-0.349), fasting plasma insulin (r=-0.483), and insulin resistance (HOMA-IR score) (r=-0.423); and a positive correlation with folate (r=0.299). In this study, there was a significant inverse correlation between plasma tHcy level and mtDNA content. Further study will be warranted to elucidate the mechanism by which two factors are associated.

General pharmacology studies on beta-domain deleted recombinant factor VIII

beta-Domain deleted recombinant factor VIII (GC-rAHF), newly developed by Korea Green Cross Co., is a novel therapeutic for hemophiliacs and is currently under clinical evaluation. The general pharmacological properties of this drug were evaluated using mice, rats, guinea pigs and rabbits. Intravenous doses of 5 to 500 IU/kg were assayed in several tests to analyze their effects in vivo on various systems. The effect of the substance under study was also tested in vitro on isolated guinea pig ileum preparations at final concentrations of 5 to 50 IU/kg. The result of this study showed that GC-rAHF did not affect general behavior in the Irwin test. Similarly the drug was not found to affect neither normal body temperature nor the spontaneous activity in mice. In addition, it was not found to induce pharmacologically significant alterations of the cardiovascular and respiratory parameters in rats. No effects were observed either in the pentobarbital sodium-induced sleep-induction time and duration, in writhing test or in the test of pentetrazole-induced convulsion. Finally, the tested drug did not modify the gastrointestinal motility, acetylcholine or histamine-induced contraction of the isolated guinea pig ileum, nor gastric secretion. The results demonstrated that GC-rAHF has no effects on the central nervous, cardiovascular, respiratory and digestive systems in the doses of 5, 50 and 500 IU/kg in vivo and 5, 10, 50 and 100 IU/kg in vitro.

Monocyclic carotenoid biosynthetic pathway in the yeast Phaffia rhodozyma (Xanthophyllomyces dendrorhous)

The biosynthetic pathway of monocyclic carotenoids in the yeast Phaffia rhodozyma was studied by identifying carotenoids, applying inhibitors of carotenoid synthesis, and analyzing the carotenoids in carotenogenic mutants. Two carotenoids, torulene and 3,3'-dihydroxy-beta,phi-carotene-4,4'-dione (DCD), were identified from the yeast. Piperonyl butoxide inhibited dehydrogenation of carotenes and caused accumulation of neurosporene, lycopene, gamma-carotene, and beta-zeacarotene. Yellow mutants of P. rhodozyma produced mainly beta-carotene, which is a dicyclic carotene produced from neurosporene through lycopene. The yellow mutants grown with 0.01% triethylamine (TEA) or 2 mM 2-methylimidazole (MI) produced significantly increased amounts of torulene, which is a monocyclic carotene produced from neurosporene through beta-zeacarotene. When red strains of P. rhodozyma were grown with TEA or MI, they produced increased amounts of beta-zeacarotene, torulene, and 3-hydroxy-3',4'-didehydro-beta,phi-carotene-4-one (HDCO) (all monocyclic). DCD, accumulated especially in old cultures, was also increased in MI or TEA cultures coincident with the increases in HDCO. We propose the following monocyclic carotenoid pathway in P. rhodozyma: neurosporene-->beta-zeacarotene-->gamma-carotene-->torulene-->HDCO-->DCD.

Ethanol increases carotenoid production in Phaffia rhodozyma

Addition of ethanol (0.2%) to cultures of the yeast Phaffia rhodozyma increased the specific rate of carotenoid production [(carotenoid)(cell mass)-1(time)-1]. The incremental increase in carotenoid synthesis with ethanol was highest in carotenoid-hyperproducing strains. Ethanol increased carotenoid production when it was added at various points during the lag and active growth phases. Ethanol increased alcohol dehydrogenase and hydroxy-methylglutaryl-CoA (HMG-CoA) reductase activities. Our results indicate that increased carotenoid production by ethanol is associated with induction of HMG-CoA reductase and possibly activation of oxidative metabolism.

Photosensitization of the yeast Phaffia rhodozyma at a low temperature for screening carotenoid hyperproducing mutants

Phaffia rhodozyma strain Ant-1 produces more carotenoids, known as antioxidants, but it was more sensitive to light plus toluidine blue O (TBO), a superoxide producer, than wild strain 67-385 at 20 degrees C. Carotenoid hyperproducing mutants (CHMs), Ant-1 and 2A2N, exhibited decreased activity of superoxide dismutase (SOD) compared to 67-385, and this is in part responsible for hypersensitivity of the mutants to photosensitization. Light plus TBO at 2 degrees C allowed carotenoid hyperproducing mutants to produce higher colony-forming units than the wild-type. Photosensitization with limited cell metabolism by a low temperature, provides an idea of selective conditions for carotenoid hyperproducers of P. rhodozyma.

Sensitization of heat-treated Listeria monocytogenes to added lysozyme in milk

Listeria monocytogenes was highly resistant to hen egg white lysozyme in whole milk but was sensitive in media and in phosphate buffer. Methods to sensitize the pathogen to lysozyme in milk were investigated. Treatment of whole milk by cation exchange to remove minerals, particularly Ca2+ and Mg2+, slightly promoted inactivation of L. monocytogenes by lysozyme at 4 degrees C over a period of 6 days. Heat treatment (62.5 degrees C for 15 s) strongly sensitized L. monocytogenes to lysozyme in demineralized milk and in MES [2-(N-morpholino)ethanesulfonic acid] buffer. Addition of Ca2+ or Mg2+ to the demineralized milk restored resistance to lysozyme. Cells were more rapidly heat inactivated at 55 degrees C in demineralized milk containing lysozyme, and addition of Ca2+ to the demineralized milk restored the resistance to heat. The results indicate that minerals or mineral-associated components protect L. monocytogenes from inactivation by lysozyme and heat in milk, probably by increasing cell surface stability. The heat treatment of foods containing added lysozyme can probably play a significant role in producing microbiologically safe foods.

Sugar response element enhances wound response of potato proteinase inhibitor II promoter in transgenic tobacco

The promoter region of the potato proteinase inhibitor II (PI-II) gene was studied to identify cis-acting regulatory sequences involved in sugar response using transgenic tobacco plants. The 5' control region covering an 892 nucleotide sequence upstream from the cap site and a 32 nucleotide untranslated region of the PI-II promoter was able to activate a reporter chloramphenicol acetyltransferase (cat) gene by wounding or by incubating in a sugar-free medium. This wound response was further enhanced by sugar. Hexoses, disaccharides, and some trisaccharides were strong inducers whereas pentoses, deoxy sugars, sugar acids, TCA cycle intermediates, amino acids, and other carbohydrates had little effect on the promoter activity. Deletion of the sequence between -892 and -573 abolished the wound response but not the sugar response. An additional 5' deletion to -453 removed the sugar inducibility. Locations of the cis-acting regulatory elements were further elucidated by 3' deletion analysis. Deletion of the downstream region from -520 did not affect the wound or sugar response of the promoter. However, 3' deletion mutant -574 was unable to respond to sugar but did respond weakly to wounding. Further deletion to -624 abolished both responses. Therefore, it can be concluded that a wound response element is located in between -624 and -574 and that the response is further enhanced by a sugar response element located in the sequence between -573 and -520.

Isolation and Characterization of Carotenoid Hyperproducing Mutants of Yeast by Flow Cytometry and Cell Sorting

The carotenoid pigment astaxanthin (3,3'-dihydroxy-beta,beta-carotene-4,4'-dione) is an important component in feeds of aquacultural animals. It is produced as a secondary metabolite by the yeast Phaffia rhodozyma, and the isolation of rare mutants that produce increased quantities is limited by the lack of genetic selections. As a model system for enriching mutants increased in production of secondary metabolites, we have used quantitative flow cytometry/cell sorting (FCCS) to isolate astaxanthin hyperproducing mutants of the yeast. Experimental conditions were developed that gave a quantitative correlation of fluorescence and carotenoid content. In mutated populations, a 10,000-fold enrichment of carotenoid-overproducing yeasts was obtained. Distinctive differences were detected by FCCS in fluorescence and forward scatter values of mutant and wild-type populations of yeasts. Comparison of wild-type and mutant clones by fluorescence confocal laser microscopy showed that the mutants had more intense fluorescence throughout the cell than the wild-type. Quantitative FCCS is a sensitive method to isolate and characterize carotenoid overproducing mutants and should be useful as a general method for the isolation of mutants increased in other fluorescent metabolites.

Influence of light on growth and pigmentation of the yeast Phaffia rhodozyma

Light and antimycin markedly affected growth and carotenoid synthesis by Phaffia rhodozyma. Exposure of the yeast to high light intensities on agar plates resulted in growth inhibition and decreased carotenoid synthesis. The carotenoid compositions of the yeast were also notably changed by light. Beta-zeacarotene increased, whereas beta-carotene and xanthophylls decreased including astaxanthin, phoenicoxanthin, and 3-hydroxy-3',4'-didehydro-beta,psi-caroten-4-one (HDCO). In liquid medium, growth of the wild-type strain (UCD-FST-67-385) was inhibited by antimycin, but this inhibition was relieved by exposure to light. Light also stimulated carotenoid synthesis about twofold in these antimycin-treated cells. Light may have rescued growth by induction of an alternative oxidase system which facilitated electron disposal when the main respiratory chain was inhibited by antimycin. Isolation and characterization of the oxidase enzymes should be useful in strain development for increased carotenoid production.

Cis-acting regulatory elements controlling temporal and organ-specific activity of nopaline synthase promoter

Regulatory elements controlling temporal and organ-specific expression of the nopaline (nos) gene were identified by analyzing deletion mutants of the promoter. As observed in cultured cells, the TATA box element was required for efficient promoter function and the 29 bp upstream promoter region between -130 and -101 was necessary for the nos promoter activity in various vegetative organs. This 29 bp region includes ten nucleotides of a potential Z-DNA-forming sequence (Z element) and eight nucleotides of a repeated element (b element). Duplication of b elements significantly enhanced the promoter strength, revealing the importance of the element in all plant organs. Unlike the results in the cultured cells, however, deletion of the b element or CCAAT box region completely inactivated the promoter function in regenerated organs. Therefore, it appears that transcription initiation is more tightly controlled in differentiated plant cells than in cultured cells.

Isolation of Phaffia rhodozyma Mutants with Increased Astaxanthin Content

Plating of the astaxanthin-producing yeast Phaffia rhodozyma onto yeast-malt agar containing 50 μM antimycin A gave rise to colonies of unusual morphology, characterized by a nonpigmented lower smooth surface that developed highly pigmented vertical papillae after 1 to 2 months. Isolation and purification of the pigmented papillae, followed by testing for pigment production in shake flasks, demonstrated that several antimycin isolates were increased two- to fivefold in astaxanthin content compared with the parental natural isolate (UCD-FST 67-385). One of the antimycin strains (ant-1) and a nitrosoguanidine derivative of ant-1 (ant-1-4) produced considerably more astaxanthin than the parent (ant-1 had 800 to 900 μg/g; ant-1-4 had 900 to 1,300 μg/g; and 67-385 had 300 to 450 μg/g). The mutant strains were compared physiologically with the parent. The antimycin mutants grew slower on ammonia, glutamate, or glutamine as nitrogen sources compared with the natural isolate and also had lower cell yields on several carbon sources. Although isolated on antimycin plates, they were found to be more susceptible to antimycin A, apparently owing to the spatial separation of the papillae from the agar. They were also more susceptible than the parent to the respiratory inhibitor thenoyltrifluoroacetone and were slightly more susceptible to cyanide, but did not differ from the natural isolate in susceptibility to azide. The antimycin-derived strains were also killed faster than the parent by hydrogen peroxide. The carotenoid compositions of the parent and the antimycin-derived strains were similar to those previously determined in the type strain (UCD-FST 67-210) except that two carotenoids not previously found in the type strain were present in increased quantities in the antimycin mutants and phoenicoxanthin was a minor component. The chemical properties of the unknown carotenoids suggested that the strains isolated on antimycin agar tended to oxygenate and desaturate carotene precursors to a greater extent than the parent. The physiology of the antimycin isolates and the known specificity of antimycin for cytochrome b in the respiratory chain suggests that alteration of cytochrome b or cytochrome P-450 components involved in oxygenation and desaturation of carotenes in mitochondria are affected, which results in increased astaxanthin production. These astaxanthin-overproducing mutants and more highly pigmented derivative strains could be useful in providing a natural source of astaxanthin for the pen-reared-salmon industry or for other farmed animals that contain astaxanthin as their principal carotenoid.