The chemical and bio-optical characterisation of gelbstoff in southern African waters : a preliminary analysis

Bibliography: pages 103-114.This study will attempt to begin the bio-optical characterisation of gelbstoff in southern African waters. Gelbstoff is a collective term, in itself perhaps an indication of a poorly understood phenomenon, given to a complex group of macromolecular organic compounds. It is the common bio-optical properties of these compounds that cause such an association, specifically the exponential decrease of absorption with increase in wavelength, resulting in typical absorption spectra decaying exponentially from a maximum in the ultra-violet. It is the accurate measurement or inferral of these spectra that is the primary aim of any bio-optical investigation of gelbstoff

Workshop on Exercise Prescription for Long-Duration Space Flight

The National Aeronautics and Space Administration has a dedicated history of ensuring human safety and productivity in flight. Working and living in space long term represents the challenge of the future. Our concern is in determining the effects on the human body of living in space. Space flight provides a powerful stimulus for adaptation, such as cardiovascular and musculoskeletal deconditioning. Extended-duration space flight will influence a great many systems in the human body. We must understand the process by which this adaptation occurs. The NASA is agressively involved in developing programs which will act as a foundation for this new field of space medicine. The hallmark of these programs deals with prevention of deconditioning, currently referred to as countermeasures to zero g. Exercise appears to be most effective in preventing the cardiovascular and musculoskeletal degradation of microgravity

Summary and recommendations for initial exercise prescription

The recommendations summarized herein constitute a basis on which an initial exercise prescription can be formulated. It is noteworthy that any exercise program designed currently would be an approximation. Examination of the existing space-flight data reveals a scarcity of in-flight data on which to rigorously design an exercise program. The relevant experience within the U.S. space program (with regard to long-duration space flight) is limited to the Skylab Program. Lessons learned from Skylab are relevant to the design of a Space Station exercise program, especially with regard to the total length of exercise time required, cardiovascular (CV) deconditioning/reconditioning, and bone loss. Certain observations of the U.S.S.R. exercise activities can also contribute to the formulation of an exercise prescription of Space Station. Reportedly, the U.S.S.R. uses both a bicycle ergometer and a treadmill device on long-duration missions with some degree of success. Using the third crew of Salyut 6, which was a 175-day stay, as a representative mission, the typical time dedicated to exercise varies from 2 to 3 hours per day. In addition, the cosmonauts wear an elasticized suit, called a penquin suit, for time periods ranging from 12 to 16 hours per day. This device provides a load across the axial skeleton against which the wearer must exert himself. Despite these extensive countermeasures, the effects of adaptation are not totally prevented

DNA-mediated gene transfer as an indicator of DNA damage and its repair by recipient cells

AbstractPreparations of plasmid containing the thymidine kinase gene (pHSV106) were treated with the alkylating agents methyl methanesulphonate or N-methyl-N-nitrosourea prior to transfection into thymidine kinase-deficient mouse L-cells using the DNA-calcium phosphate co-precipitation technique. Relative to transfection with unmodified plasmid, a reduced transformation efficiency was observed using alkylation-damaged plasmid, N-methyl-N-nitrosourea causing the greatest inhibition. Treatment of recipient cells with arabinosyl cytosine or dideoxythymidine during the expression period following transfection by the ‘damaged’ plasmid reduced transformation efficiency, suggesting that DNA repair 4–6 h post-transfection was required for gene expression

Digestion of Repair Sites in Rat Liver DNA by Endogenous Nucleases

The proportion of sheared rat liver DNA recovered from benzoylated DEAE-cellulose in the final stage following stepwise elution with NaCl and caffeine solutions was dependent upon the DNA isolation procedure. An increase in the proportion of DNA containing single stranded regions, consequent upon delay or addition of Mg2+ prior to phenol extraction, suggested nuclease mediated degradation. Administration of methyl methanesulphonate to rats resulted in a consistent proportional increase in the caffeine-eluted fraction. The results of caffeine gradient elution of control and alkylated DNA from benzoylated DEAE-cellulose were consistent with repair-associated single stranded regions being substrates for endogenous single strand-specific exonucleases

Nucleon-Nucleon Interactions on the Lattice

We consider the nucleon-nucleon potential in quenched and partially-quenched QCD. The leading one-meson exchange contribution to the potential is found to fall off exponentially at long-distances, in contrast with the Yukawa-type behaviour found in QCD. This unphysical component of the two-nucleon potential has important implications for the extraction of nuclear properties from lattice simulations.Comment: 6 pages LaTeX, 2 eps fig

Radiation pions in two-nucleon effective field theory

For interactions involving two or more nucleons it is useful to divide pions into three classes: potential, radiation, and soft. The momentum threshold for the production of radiation pions is $Q_r = \sqrt{M_N m_\pi}$. We show that radiation pions can be included systematically with a power counting in $Q_r$. The leading order radiation pion graphs which contribute to NN scattering are evaluated in the PDS and OS renormalization schemes and are found to give a small contribution. The power counting for soft pion contributions is also discussed.Comment: 21 pages, 3 figs, journal versio

A Population-Based Study of Pregnancy and Delivery Characteristics Among Women with Vulvodynia

Introduction: To examine pregnancy and delivery characteristics of women with and without vulvodynia. Methods: The authors analyzed 227 vulvodynia cases that were less than 45 years old at pain onset; controls were age matched 1:1 to cases and had no history of vulvar pain. Pregnancy and delivery events were assessed after age at first vulvar pain onset (the reference age) in cases and a matched age in controls. Results: The authors observed no significant difference between cases and controls in achieving pregnancy after reference age. Also, no difference in pregnancy outcome was observed between cases and controls (P = 0.87). There was an indication that cases were more likely to receive a Cesarean section delivery (P = 0.07). In addition, 37.1% of cases who had vaginal delivery versus 11.3% of controls (P < 0.01) reported pain at 2 months postpartum. Comparing only women with vulvodynia, women who had intermittent pain versus constant pain were more than twice as likely to have a pregnancy (adjusted odds ratio 2.26, 95% CI 1.10–4.60). Conclusions: Women with vulvodynia may be as likely as other women to carry their pregnancy to birth; however, they may experience higher rates of Cesarean section delivery and could reflect a selection towards those women with vulvodynia who have inconsistent pain

The PPAR Gamma Agonist Troglitazone Regulates Erk 1/2 Phosphorylation via a PPARγ-Independent, MEK-Dependent Pathway in Human Prostate Cancer Cells

Thiazolidinediones (TZDs) dramatically reduce the growth of human prostate cancer cells in vitro and in vivo. To determine whether the antitumor effects of TZDs were due in part to changes in the MEK/Erk signaling pathway, we examined the regulation of Erk phosphorylation by the TZD troglitazone within the PC-3 and C4-2 human prostate cancer cell lines. Western blot analysis revealed troglitazone-induced phosphorylation of Erk in both PC-3 and C4-2 cells. Troglitazone-induced increases in Erk phosphorylation were suppressed by the MEK inhibitor U0126 but not by the PPARγ antagonist GW9662. Pretreatment with U0126 did not alter the ability of troglitazone to regulate expression of two proteins that control cell cycle, p21, and c-Myc. Troglitazone was also still effective at reducing PC-3 proliferation in the presence of U0126. Therefore, our data suggest that troglitazone-induced Erk phosphorylation does not significantly contribute to the antiproliferative effect of troglitazone

Lattice Calculation of Heavy-Light Decay Constants with Two Flavors of Dynamical Quarks

We present results for $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$ and their ratios in the presence of two flavors of light sea quarks ($N_f=2$). We use Wilson light valence quarks and Wilson and static heavy valence quarks; the sea quarks are simulated with staggered fermions. Additional quenched simulations with nonperturbatively improved clover fermions allow us to improve our control of the continuum extrapolation. For our central values the masses of the sea quarks are not extrapolated to the physical $u$, $d$ masses; that is, the central values are "partially quenched." A calculation using "fat-link clover" valence fermions is also discussed but is not included in our final results. We find, for example, $f_B = 190 (7) (^{+24}_{-17}) (^{+11}_{-2}) (^{+8}_{-0})$ MeV, $f_{B_s}/f_B = 1.16 (1) (2) (2) (^{+4}_{-0})$, $f_{D_s} = 241 (5) (^{+27}_{-26}) (^{+9}_{-4}) (^{+5}_{-0})$ MeV, and $f_{B}/f_{D_s} = 0.79 (2) (^{+5}_{-4}) (3) (^{+5}_{-0})$, where in each case the first error is statistical and the remaining three are systematic: the error within the partially quenched $N_f=2$ approximation, the error due to the missing strange sea quark and to partial quenching, and an estimate of the effects of chiral logarithms at small quark mass. The last error, though quite significant in decay constant ratios, appears to be smaller than has been recently suggested by Kronfeld and Ryan, and Yamada. We emphasize, however, that as in other lattice computations to date, the lattice $u,d$ quark masses are not very light and chiral log effects may not be fully under control.Comment: Revised version includes an attempt to estimate the effects of chiral logarithms at small quark mass; central values are unchanged but one more systematic error has been added. Sections III E and V D are completely new; some changes for clarity have also been made elsewhere. 82 pages; 32 figure