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- Ståhle, Lars, et al.
(författare)
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Effects of Food or Sleep Deprivation During Civilian Survival Training on Clinical Chemistry Variables
- 2013
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Ingår i: Wilderness & environmental medicine (Print). - : Elsevier BV. - 1080-6032 .- 1545-1534. ; 24:2, s. 146-152
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Tidskriftsartikel (refereegranskat)abstract
- Objective.-To describe clinical chemistry and weight changes after short-term food or sleep deprivation or multiple deprivations during civilian survival training. Methods.-Data from one baseline-controlled two-period crossover study designed to compare sleep deprivation for up to 50 hours with food deprivation for up to 66 hours (n = 12) and data from regular multiple-deprivations survival training comparing participants (n =-33) with nondeprived instructors (n = 10). Results.-Food deprivation was associated with decreased body weight, blood glucose, serum triglycerides, sodium, chloride, and urine pH, and there were increases in blood and urine ketones and. serum free fatty acids. Sleep deprivation was associated with a minor decrease in hemoglobin and erythrocyte particle count and volume fraction and an increase in leukocytes. Conclusions.-The clinical chemistry and body weight changes associated with food deprivation were qualitatively similar to those observed in fasting obese patients but developed quicker in the survival training setting. Sleep deprivation had few effects on the clinical chemistry profile except for hematological variables. Physicians evaluating clinical chemistry data from patients subjected to short-term food or sleep deprivation should take the physiological state into account in their assessment.
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| 2. |
- Ståhle, Lars, et al.
(författare)
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Effects of Sleep or Food Deprivation During Civilian Survival Training on Cognition, Blood Glucose and 3-OH-butyrate
- 2011
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Ingår i: Wilderness & environmental medicine (Print). - 1080-6032 .- 1545-1534. ; 22:3, s. 202-210
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Tidskriftsartikel (refereegranskat)abstract
- Objectives.-The study was designed to compare effects of food deprivation (FD) and sleep deprivation (SD) on cognition during survival training. Methods.-In a cross-over design (n = 12), the effects of FD (up to 66 hours followed by 500 kcal intake over 24 hours) and SD (up to 50 hours) on cognitive variables, blood glucose, and 3-OH-butyrate were studied. Results.-Food deprivation and SD impaired attention-dependent tasks. The FD impairment of simple reaction time was independent of blood glucose levels, which were normalized by a 500 kcal intake over 24 hours while the reaction time was not. Sleep deprivation and FD impaired maze-solving performance on all variables except rule breaks, which were significantly occurring after 50 hours of SD. Delayed word recall was impaired by SD for 50 hours. On the Balloon Analogue Risk Task, SD was associated with reduced risk-taking. In a gambling task, both SD for 50 hours and FD for 66 hours were associated with a tendency to make early choices when presented with consecutive choices, but the risk-taking was not affected. Conclusions.-Sleep deprivation has multiple cognitive effects, including attention, memory, visual-spatial ability, and risk-taking. Food deprivation had no affect on risk-taking, while the other tasks were affected in a way similar to SD but were less pronounced. The FD effects on cognition did not appear to depend on blood sugar levels. The need to sleep should be prioritized in survival situations to avoid cognitive impairment.
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| 3. |
- Ljungdahl Ståhle, Ewa
(författare)
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In vivo and in vitro models for determination of antiviral activity and resistance
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The AIDS epidemic has been the driving force for the discovery of substances that inhibit the replication of human immunodeficiency virus (HIV). Much interest has earlier focused on a single gene product central to the life cycle of HIV and to all other retroviruses: the reverse transcriptase (RT), the enzyme responsible for synthesis of DNA from viral RNA. Analogues to the five naturally occurring nucleosides can inhibit the replication of retroviruses in cell culture to various degrees. Another enzyme critical for HIV replication is the viral protease. Inhibition of this enzyme leads to production of immature noninfectious viral progeny. The aim of this thesis was to develop and use methods required for the preclinical development and laboratory testing of antiviral drugs. In order to monitor in vivo challenge models for retrovirus infection, we developed assays to identify viral antigens and immune responses to them. The antibody assay was based on a synthetic peptide, the sequence of which corresponds to a segment of the env protein of HIV-2 which cross reacts with SIV. The peptide was successfully used to detect IgM antibodies from days 13-16 after SIV infection and anti-SIV IgG antibody levels around days 16-20 which attained a plateau after two months. In the development of new drugs it is imperative to use animal models for the study of therapies against AIDS and HIV infection. In this study monkeys were infected with 10-100 monkey infectious doses of SIV SM and treated for ten days with foscamet or one of four different nucleoside analogues. Foscamet, zidovudine, fluorothymidine, didanosine, and stavudine significantly delayed the appearance of SIV SM p24/26 antigen. Foscarnet also decreased IgM and delayed IgG antibodies. In our studies, infection was not prevented by any of the drugs investigated, but later studies of fluorothymidine have prevented infection when smaller infectious doses have been used. A major clinical problem in the management of AIDS is the presence of neuropsychiatric symptoms. It is therefore valuable if a drug against HIV penetrates the blood-brain barrier. Microdialysis is a method of sampling extracellular fluid containing free(not protein-bound) drugs in the brain and other tissues. Using microdialysis, the concentration of the nucleoside analogues fluorothymidine and zidovudine in the brain were found to be approximately one-third those in the muscle and plasma in monkeys and one-fifth in rats. The in vivo unbound concentrations of both drugs in the brain, muscle and venous blood exceeded those reported to inhibit HIV replication in vitro. The method allows comparisons of the efficacy of antiviral drugs in penetrating the blood-brain barrier. Herpesvirus infections are common among AIDS patients; more than half of them had evidence of disseminated cytomegalovirus infection at autopsy. A method for measurement of antiviral sensitivity of primary isolates of CMV was developed. The assay includes simultaneous virus titration and determination of the 50 % inhibitory concentration(IC5O). The absorbance obtained in the enzyme-linked immunosorbent assay correlated linearly to the number of plaques in a plaque reduction assay. The IC5O of antiviral compounds was strongly dependent on the virus dose, except for resistant isolates, where the IC50 did not change with the viral dose. Clinical isolates exhibited different IC50 values for ganciclovir in different cell types indicating that intracellular factors are important for drug metabolism. The effect of drug combinations may also be primarily evaluated in vitro. Combinations of RT and protease inhibitors not only target two different proteins but also affect two different stages of the viral life cycle of HIV. Combinations of foscarnet and lamivudine, both inhibitors of RT, showed clear synergy and this effect was further pronounced using two more potent foscarnet analogues. A weak or no synergy was found when foscarnet was combined with the protease inhibitors indinavir, saquinavir or ritonavir.
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