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PubMed2001

DNA strand break yields after post-high LET irradiation incubation with endonuclease-III and evidence for hydroxyl radical clustering.

PURPOSE: To determine the increase in single- (SSB) and double-strand break (DSB) yields after post-high LET irradiation incubation of plasmid DNA with the endonuclease-III (endo-III) of Escherichia coli. MATERIALS AND METHODS: Plasmid DNA in aerobic aqueous solution was irradiated with one of five radiation types: 137Cs gamma-rays (LET approximately 0.3keV microm(-1)), 244Cm alpha-particles (140-190 keV microm(-1)), 4He ions (97 keV microm(-1)), 56Fe ions (143 keV microm(-1)) or 197Au ions (1,440 keV microm(-1)). The irradiated samples were then incubated with endo-III. SSB and DSB yields were quantified by agarose gel electrophoresis. RESULTS: Endo-III incubation produced an increase in the SSB and DSB yields. The increases were in general lower after the high LET irradiation than after gamma-irradiation. This may reflect inhibition of the activity of endo-III by the nearby DNA damage expected from high LET radiation. It can be shown that even if the activity of endo remains unchanged, significantly lower increases in SSB and DSB yields would still be expected. CONCLUSION: The results provide evidence for clustered DNA damage after high LET irradiation.

Cesium Radioisotopes↗
PubMed2001

Redox equilibrium between guanyl radicals and thiocyanate influences base damage yields in gamma irradiated plasmid DNA. Estimation of the reduction potential of guanyl radicals in plasmid DNA in aqueous solution at physiological ionic strength.

PURPOSE: Gamma irradiation of an aqueous solution containing thiocyanate ions produces the strongly oxidizing intermediate (SCN)2*-. Reaction of this species with plasmid DNA produces damage that is revealed as strand breaks after incubation with the Escherichia coli base excision repair endonuclease formamidopyrimidine-DNA N-glycosylase (FPG). It has been previously reported that the yield of damage is highly sensitive to the experimental conditions, leading to the suspicion that electron transfer between DNA and (SCN)2*- is reversible. In principle this makes it possible to determine the oxidation potential for plasmid DNA (more formally the reduction potential of one-electron oxidized plasmid DNA), a fundamental parameter describing the reactivity of DNA towards electron transfer reactions. MATERIALS AND METHODS: Aqueous solutions of plasmid DNA and thiocyanate ions were subjected to 137Cs gamma-irradiation. After irradiation, the plasmid was incubated with the E. coli base excision repair endonuclease formamidopyrimidine-DNA N-glycosylase (FPG). The yield of this damage was quantified by using agarose gel electrophoresis to identify the fraction of the plasmid population that contains strand breaks. RESULTS: The yield of FPG-sensitive sites decreases with increasing thiocyanate concentration, decreasing DNA concentration, and increasing dose rate. By making some simple assumptions about the chemical reactions that produce DNA damage, it is possible to derive a quantitative mathematical model for the yield of FPG-sensitive sites. A good agreement was found between this model and the experimental observations over a wide range of conditions (thiocyanate concentrations, DNA concentrations, and dose rates that vary by 20-, 40-, and 150-fold respectively). CONCLUSIONS: It was possible to assign a value to the equilibrium constant for the one electron transfer reaction between the two radical species (SCN)2*- and DNA-G*+. This leads to an estimate of the reduction potential at pH 7 for the couple DNA G*+/DNA of E7 = +1.39+/-0.01V.

DNA↗
PubMed1992

Direct comparison of biological effectiveness of protons and alpha-particles of the same LET. III. Initial yield of DNA double-strand breaks in V79 cells.

The results reported form part of a series of experiments to substantiate and extend the findings by Belli et al. (1989) that protons are more biologically effective at cell killing than alpha-particles of the same LET. The irradiations were carried out using the Variable Energy Cyclotron (VEC) at the Harwell Laboratories. V79-4 Chinese hamster cells were exposed to alpha-particles and protons with LETs of 20 and 23 keV microns-1 in the dose range 40-150 Gy. X-rays were also used for comparison. Two methods were used for measurement of initial DNA double-strand breaks: sedimentation and DNA precipitation assays. The dose-response relationships were found to be well fitted by straight lines in all cases. With the sedimentation assay a slightly lower yield of dsb was found from protons than from alpha-particles of the same LET. The yield from X-rays was not significantly different from either. The precipitation assay showed similar yields of DNA damage from both particle types but significantly higher yields from X-rays. This may reflect a difference in the type of lesions scored by the two methods. Since the initial amount of dsb does not account for the observed differences in cellular response to radiations of different qualities, it is likely that these are related to the nature of the dsb (affecting reparability) or to the occurrence of other types of molecular damage.

Alpha Particles↗
PubMed1993

Dependence of the yield of strand breaks induced by gamma-rays in DNA on the physical conditions of exposure: water content and temperature.

The induction by 60Co gamma-rays of DNA breaks, revealed by relaxation (single-strand breaks, SSBs) and linearization (double-strand breaks, DSBs) of supercoiled plasmid DNA, was measured under three irradiation conditions, the DNA being in a dry, humid, or aqueous state in the absence of oxygen, at 25 or -196 degrees C (77 K). Yields of strand breaks (3.0 x 10(-10) SSB/Gy.Da and 2.6 x 10(-11) DSB/Gy.Da) in DNA exposed to a stream of humidified nitrogen were higher than those in the dry condition (5.7 x 10(-11) SSB/Gy.Da and 3.2 x 10(-12) DSB/Gy.Da), but both these yields were markedly lower than those measured for DNA in aqueous solution at a concentration of 73 micrograms/cm3 (1.14 x 10(-7) SSB/Gy.Da and 5.4 x 10(-9) DSB/Gy.Da). Over 100-fold fewer SSBs were observed in the frozen aqueous system compared with the non-frozen liquid state, whereas in the dry and humid states, freezing did not affect the yield as much. The same trend was observed for DSBs. However, the induction of SSBs was more affected than that of DSBs by freezing in the aqueous systems. An interesting reverse relationship was observed in humid systems. The observed linearity of DSB induction with radiation dose supported a single-event mechanism. A comparison of G values for humid systems revealed that the role of bound water in radiation damage becomes significant in the nonfrozen state. Based on these and other measurements of strand breaks under different conditions, the significance of bound and free water on the yields of DNA strand breaks by gamma-rays is discussed, and the relevance of these results to the in vivo situation outlined.

Cobalt Radioisotopes↗
PubMed1993

Technical note: comparison of yields and repair kinetics of interphase chromosome breaks visualized by Sendai-virus or PEG-mediated cell fusion in irradiated CHO cells.

We examined the initial yields and the kinetics of rejoining of interphase chromosome breaks in irradiated plateau-phase Chinese hamster ovary cells by means of premature chromosome condensation (PCC) using either Sendai virus or polyethylene glycol (PEG) as fusogens. We found a yield of 2.2 chromosome breaks/cell/Gy independently of the method used to induce PCC. Rejoining of interphase chromosome breaks also proceeded with identical kinetics in cells fused using either Sendai virus or PEG. In an additional set of experiments, we compared the kinetics of rejoining of interphase chromosome breaks in cells synchronized in G1 phase by elutriation to that measured in plateau-phase cells, using either Sendai virus or PEG as fusogens. Here again, the rejoining kinetics were not affected by the fusogen used, and were similar in synchronized G1 and plateau-phase cells. These observations suggest that both methods of fusion give equivalent results in terms of yields and rejoining kinetics of interphase chromosome breaks. They also suggest that differences in the fusogens or the metabolic state of the cells cannot explain differences in the yields, and probably also the kinetics of the rejoining of interphase chromosome breaks that have been reported elsewhere. Cell line characteristics and other as of yet unidentified technical parameters may underlie these differences.

Animals↗
PubMed1999

A Novel 3D Microstructural Model for Trabecular Bone: II. The Relationship Between Fabric and the Yield Surface.

A novel 3D microstructural model was proposed and validated in part I of this publication. In part II, the model was used to identify the yield surface of a representative volume element of human trabecular bone as a function of volume fraction and degree of anisotropy. Finite element models of open and closed cells geometries were used to calculate effective yield stresses for a variety of loading cases with periodic boundary conditions. The postyield behaviour of the trabecular tissue was assumed from data available for cortical tissue. The yield stresses defined by a 0.2% offset in the global stress-strain curve were fit to an orthotropic Hill criterion and the parameters of the surface calculated. Similarly to the previous elastic analysis, distinct but strong relationships were obtained between volume fraction, fabric and the yield surface parameters for both the open and closed cell geometries. This finding suggests that volume fraction and fabric may be used to predict the initiation of mechanical damage in human trabecular bone at the continuum level.

Journal Article↗
PubMed2001

Subjective and discriminative stimulus effects of two de-nicotinized cigarettes with different tar yields.

The role of tar yield in the subjective and discriminative stimulus effects of cigarette smoking was examined. Current smokers (n=18) smoked two non-nicotine cigarettes with FTC yields of 0.06 mg nicotine and 12.4 mg (low tar) or 17.9 mg tar (high tar). Physiological measures and visual analog scales were completed over a 30-min period. Dosing order was determined randomly and counterbalanced. After sampling both cigarettes, volunteers smoked a third, test cigarette. Half of the volunteers received the low-tar cigarette and half the high-tar cigarette. Volunteers identified the test cigarette (i.e., A or B) at 5, 30, 60, 300, and 900 s after the first puff. Eight of the eighteen participants correctly identified the test cigarette on 4/5 of trials. No significant changes in visual analog scale scores were found among the non-discriminators. However, among discriminators, the low-tar cigarette produced significant positive effects including good drug effects and stimulation relative to the high-tar cigarette. Relative to the low-tar cigarette, the high-tar cigarette produced negative effects including harshness, heaviness, and intensity of flavor. Average tar yield of these participants' usual cigarettes was 9.75 mg, lower than that of the low-tar cigarette used here, possibly accounting for their greater liking of the low-tar cigarette. No changes in blood pressure or heart rate were observed and both cigarettes produced similar carbon monoxide increases, indicating similar depth of inhalation when smoking each. Results suggest cigarette tar yields may play a role in cigarette smoking preferences. Further research is needed to verify whether preferences are maintained after associations with nicotine delivery are extinguished.

Adult↗
PubMedDate not supplied

Estimating the hazards of less hazardous cigarettes. II. Study of cigarette yields of nicotine, carbon monoxide, and hydrogen cyanide in relation to levels of cotinine, carboxyhemoglobin, and thiocyanate in smokers.

Yields of chemical constituents such as tar, nicotine, CO, and HCN defined by smoking machines are commonly assumed to provide a reasonable indication of the relative hazard associated with smoking a given brand of cigarette. Results reported here suggest that this assumption should be carefully reexamined. A total of 240 subjects, representing a wide range of smoking and brand characteristics, were recruited for an investigation of possible relations between brand yields and exposure (levels of carboxyhemoglobin, breath CO, plasma cotinine, plasma thiocyanate, and saliva thiocyanate). Exposure was highly correlated with consumption (number of cigarettes per day), but their was no correlation between any estimate of exposure and brand yield when level of consumption was held constant. In addition, a comparison of levels of carboxyhemoglobin and plasma thiocyanate for 16 smokers of "low-hazard" and 15 smokers of "high-hazard" cigarette brands revealed little difference between the two groups, even though average cigarette yields differed as much as 2- to 3-fold. A possible explanation for the results may be that current values for average puff volume, duration, and interval differ significantly from those used in programming smoking machines, particularly in the case of brands with low nicotine delivery.

Absorption↗
PubMed1993

[The effect of bovine growth hormone on the production criteria of dairy cows during summer feeding with grass. 2. Milk yield, milk composition and live weight].

The influence of long-term administration of bovine growth hormone (bGH) with prolonged release (Somidibove from Lilly Germany GmbH, section Elanco) on milk yields, milk composition and live weights in six following injection periods of 28 days each was investigated. 30 dairy cows were divided into 15 blocks of two, each pair in consideration of milk yield in a preperiod, days postpartum and number of calving. One animal in each block received the bGH treatment (640 mg bGH/28 days). Concentrate feeding of the bGH-treated cows acted according to the control animal in each block. The forage intake from grass was ad libitum. During all six injection periods the bGH-treated cows had a higher milk yield of 1.3 kg/day (P < or = 0.13). Milk fat content was unchanged, milk protein content was in relation to the changes from preperiod significantly higher in the bGH-treated group. Each injection resulted in a curvilinear response curve of daily milk yield, milk fat and milk protein content. Milk lactose content was not affected by the bGH-treatment.

Animals↗
PubMed2004

Increased milk yield in transgenic mice expressing insulin-like growth factor 1.

Insulin-like growth factor 1 (IGF-1) mediates many of the actions of growth hormone. Overexpression of IGF-1 was reported to have endocrine and paracrine/autocrine effects on somatic growth in transgenic mice. To study the paracrine/autocrine effects of IGF-1 in mammary gland, transgenic mice were produced by pronuclear microinjection of a construct containing a bovine alpha-lactalbumin (alpha-LA) promoter linked to an ovine IGF-1 cNDA. This alpha-LA promoter has previously been shown to direct expression of a human factor VIII gene specifically to the mammary gland of transgenic mice. Three transgenic mouse lines were established as a result of microinjection of 398 embryos. Transgene expression was found in mammary gland at day 1 of lactation from these three lines. Progeny test were carried out by mating two transgenic males/one transgenic female to two nontransgenic females/one nontransgenic male. Mice from one line (line 1225) were all nonexpressors and the other (line 1372) failed to produce offspring. Milk yield was analyzed in the line 1137 that produced 10 mice, of which three were transgenic females and three nontransgenic females. All of the three transgenic females showed integration of the transgene and expressed transgene IGF-1 mRNA in the mammary gland. Milk yields from days 5, 10, and 15 of lactation were significant greater in transgenic expressors than in their nontransgenic littermates. Specifically, there is 17.9% increase in total milk yield from these three days for transgenics compared with nontransgenics. These results demonstrate that local overexpression of IGF-1 in transgenic mice is capable to stimulating milk yield during the first lactation.

Animals↗
PubMed1994

Marrow cellularity as a predictor of adequate cell yield for transplantation.

Clear correlations have not been established between bone marrow cellularity before or at marrow harvest and marrow cell yield for transplantation. The authors therefore retrospectively reviewed 204 marrow donations to ascertain whether biopsy cellularity was predictive of nucleated cell yield at harvest, as measured by final cell counts (FCC)/kg body weight. Preharvest and intraoperative biopsy cellularity were highly correlated with each other; moderate correlation was found between intraoperative biopsy cellularity and FCC. Mean cellularity was slightly but significantly higher in samples yielding an FCC greater than 2 x 10(8) nucleated cells/kg (P < 0.01). Biopsy cellularity less than 20%, seen in 4% of specimens, did not consistently correlate with low FCC, defined as less than 2 x 10(8) nucleated cells/kg. More than 2 x 10(8) cells/kg were consistently obtained only when biopsy cellularity was 65% or more. Marrow biopsies performed before harvest can be used to predict intraoperative cell counts at the time of marrow donation, although a cell yield of more than 2 x 10(8) nucleated cells/kg can be assured only with high marrow cellularity.

Adolescent↗
PubMed1979

Diagnostic yield of transbronchoscopic biopsies.

Transbronchoscopic biopsies of lung (transbronchial) or bronchus (endobronchial) have a high diagnostic of yield when performed by a single expert bronchoscopist or a small group of expert bronchoscopists. This procedure's diagnostic yield was evaluated in a general hospital where biopsies are performed by a diverse group of individuals. One hundred fifty-one consecutive biopsies were reviewed, including 53 transbronchial biopsies and 98 endobronchial biopsies. Only 44% of endobronchial biopsies and 21% of transbronchial biopsies were diagnostic. The diagnostic yield was significantly greater in patients with suspected neoplasms (48%) than in patients with suspected infections (13%). Of 97 patients who ultimately had definitive diagnoses established, 43 (44%) had negative biopsy results, including 36% of those with cancers and 80% of those with infections. Failure to obtain alveolar parenchyma by transbronchial biopsy (probably related to the absence of fluoroscopic control) and failure to obtain multiple tissue fragments during each procedure contributed to the low diagnostic yield. The especially disappointing results of transbronchial biopsy for diagnosis of infection suggest that, in this hospital setting, open lung biopsy may be the procedure of choice when infection is suspected.

Biopsy↗
PubMed2000

The type and yield of lipopolysaccharide from symbiotically deficient rhizobium lipopolysaccharide mutants vary depending on the extraction method.

At least 18 lipopolysaccharide (LPS) extraction methods are available, and no single method is universally applicable. Here, the LPSs from four R.etli, one R.leguminosarum bv. trifolii mutant, 24AR, and the R.etli parent strain, CE3, were isolated by hot phenol/water (phi;/W), and phenol/EDTA/triethylamine (phi/EDTA/TEA) extraction. The LPS in various preparations was quantified, analyzed by deoxycholate polyacrylamide gel electrophoresis (DOC-PAGE), and by immunoblotting. These rhizobia normally have two prominent LPS forms: LPS I, which has O-polysaccharide, and LPS II, which has none. The LPS forms obtained depend on the method of extraction and vary depending on the mutant that is extracted. Both methods extract LPS I and LPS II from CE3. The phi/EDTA/TEA, but not the phi/W, method extracts LPS I from mutants CE358 and CE359. Conversely, the phi;/W but not the phi;/EDTA/TEA method extracts CE359 LPS V, an LPS form with a truncated O-polysaccharide. phi/EDTA/TEA extraction of mutant CE406 gives good yields of LPS I and II, while phi/W extraction gives very small amounts of LPS I. The LPS yield from all the strains using phi/EDTA/TEA extraction is fairly consistent (3-fold range), while the yields from phi/W extraction are highly variable (850-fold range). The phi/EDTA/TEA method extracts LPS I and LPS II from mutant 24AR, but the phi/W method partitions LPS II exclusively into the phenol phase, making its recovery difficult. Overall, phi/EDTA/TEA extraction yields more forms of LPS from the mutants and provides a simpler, faster, and less hazardous alternative to phi/W extraction. Nevertheless, it is concluded that careful analysis of any LPS mutant requires the use of more than one extraction method.

Carbohydrate Sequence↗
PubMed1994

Nonimmunoselected intrastrain genetic variation detected in pairs of high-yielding influenza A (H3N2) vaccine and parental viruses.

Seven influenza A (H3N2) high-yielding vaccine candidate strains were examined. Antigenic analysis revealed that 5 of the strains could be distinguished antigenically from their corresponding wild type parent viruses. Comparative sequence data for the HA1 domains of the HA (hemagglutinin) genes for these 5 high-yielding viruses and the corresponding wild type parents demonstrated one to three amino acid substitutions within each virus pair, with at least one amino acid change being located in a previously defined antigenic site. Comparison of the HA sequences of the 2 antigenically indistinguishable virus pairs revealed no amino acid differences in 1 and one amino acid change in the other. Examination of 1 additional wild type virus, A/Guangdong/39/89, and its three high-yielding derivatives obtained either by serial egg passage or by reassortment revealed an additive effect of the HA and M genes in creating the high-yielding phenotype.

Amino Acid Sequence↗
PubMed2004

Boll injury and yield losses in cotton associated with brown stink bug (Heteroptera: Pentatomidae) during flowering.

Brown stink bug, Euschistus servus (Say), was infested on cotton, Gossypium hirsutum L., plants during reproductive stages to determine the effects on boll injury and seedcotton yield. During each week in 2002 and 2003, significantly more bolls with > or = 1 injured locule, bolls with > or = 2 injured locules, and bolls with discolored lint were recorded on stink bug-infested plants compared with that on noninfested plants. Significantly fewer bolls displayed external injury on the boll exocarp compared with bolls with only internal locule injury. Boll injury was significantly underestimated by the presence of external symptomology. The boll population increased 6.6- and 5.1-fold from weeks 1-5 in 2002 and 2003, respectively. There was a corresponding 6.2- and 4.6-fold increase in 2002 and 2003, respectively, for total bolls injured from weeks 1-5. Percentage of boll injury ranged from 10.7 (week 4) to 27.4 (week 2) in 2002 and from 9.2 (week 3) to 16.0 (week 2) in 2003. Percentage of injury was greatest during weeks 1 and 2 in both years and also in week 5 in 2002. Brown stink bug significantly reduced seedcotton yield of bolls present on cotton plants during weeks 1, 2, and 5 in 2002 and in weeks 4 and 5 in 2003. However, total seedcotton yield, as a function of bolls exposed to brown stink bug and subsequent bolls produced on plant in the absence of stink bugs, was not significantly different for plots infested during weeks 1-4 in 2002 and weeks 1-3 in 2003. Flowering period and boll population influence the severity of stink bug injury on seedcotton yield. Infestation timing and number of bolls should be considered, in addition to insect densities, when initiating treatments against brown stink bug.

Animals↗
PubMed2005

Effect of soil potassium availability on soybean aphid (Hemiptera: Aphididae) population dynamics and soybean yield.

Studies were conducted to examine the effect of potassium (K) on soybean aphid, Aphis glycines Matsumura, population growth. A laboratory feeding assay examined the effect of K-deficient foliage on life table parameters of soybean aphids, and field experiments were designed to determine the effect of three soil K treatment levels on aphid populations and their impact on soybean yields. The feeding assay found that life table parameters differed between aphids feeding on the K-deficient and nondeficient soybean leaves. Soybean aphids in the K-deficient treatment exhibited significantly greater intrinsic rate of increase (r(m)), finite rate of increase (lambda), and net reproductive rate (Ro) relative to aphids feeding on nondeficient leaves. No significant difference was observed in mean generation time (T) between the two treatments. However, the field experiment repeated over 2 yr showed no effect of K on soybean aphid populations. Soybean aphid populations were high in unsprayed plots and feeding resulted in significant yield losses in 2002 at all three K treatment levels: when averaged across 2001 and 2002, unsprayed treatments yielded 22, 18, and 19.5% less than the sprayed plots in the low, medium, and high K treatments, respectively. No significant interaction was observed between aphid abundance and K level on soybean yields in either year. This study therefore suggests that although aphids can perform better on K-deficient plants, aphid abundance in the field may be dependent on additional factors, such as dispersal, that may affect final densities within plots.

Animals↗
PubMed2005

Influence of larval stage and virus inoculum on virus yield in insect host Neodiprion abietis (Hymenoptera: Diprionidae).

Virus yield produced by dead larvae of balsam fir sawfly, Neodiprion abietis (Harris) (Hymenoptera: Diprionidae), that had been infected at four different larval stages (second, third, fourth, or fifth instar) with two virus concentrations (10(5) polyhedral inclusion bodies (PIB) /ml or 10(7) PIB/ml), were analyzed and compared to determine the effects of instar and amount of virus inoculum on virus production. The results indicate that both larval stage and inoculation dosage significantly affect virus yield. On average, each dead larva produced 1.36-12.21 x 10(7) PIB, depending upon larval age and virus concentration of inoculation. Although each dead larva produced more PIB when it was inoculated in the fourth or fifth stage, inoculation of these larvae did not result in the highest virus yield because of low larval mortality. In terms of net virus return, third instars would maximize virus yield when they are inoculated with a virus concentration that can cause 95-100% larval mortality.

Animals↗
PubMed2001

The relationship between photosystem II efficiency and quantum yield for CO(2) assimilation is not affected by nitrogen content in apple leaves.

Bench-grafted Fuji/M.26 apple (Malus domestica Borkh.) trees were fertigated with different concentrations of nitrogen by using a modified Hoagland's solution for 45 d. CO(2) assimilation and photosystem II (PSII) quantum efficiency in response to incident photon flux density (PFD) were measured simultaneously in recent fully expanded leaves under low O(2) (2%) and saturated CO(2) (1300 micromol mol(-1)) conditions. A single curvilinear relationship was found between true quantum yield for CO(2) assimilation and PSII quantum efficiency for leaves with a wide range of leaf N content. The relationship was linear up to a quantum yield of approximately 0.05 mol CO(2) mol(-1) quanta. It then became curvilinear with a further rise in quantum yield in response to decreasing PFD. This relationship was subsequently used as a calibration curve to assess the rate of non-cyclic electron transport associated with Rubisco and the partitioning of electron flow between CO(2) assimilation and photorespiration in different N leaves in response to intercellular CO(2) concentration (C(i)) under normal O(2) conditions. Both the rate of non-cyclic electron flow and the rate of electron flow to CO(2) or O(2) increased with increasing leaf N at any given C(i). The percentage of non-cyclic electron flow to CO(2) assimilation, however, remained the same regardless of leaf N content. As C(i) increased, the percentage of non-cyclic electron flow to CO(2) assimilation increased. In conclusion, the relationship between PSII quantum efficiency and quantum yield for CO(2) assimilation and the partitioning of electron flow between CO(2) assimilation and photorespiration are not affected by N content in apple leaves.

Carbon Dioxide↗