U.V. enhanced reactivation of U.V.-and gamma-irradiated adenovirus in Cockayne syndrome and Xeroderma pigmentosum fibroblasts

U.V.-enhanced reactivation (UVER) of both U.V.-irradiated and gamma-irradiated human adenovirus type 2 (Ad 2) was examined following the infection of a variety of Cockayne Syndrome (CS) and Xeroderma pigmentosum (XP) fibroblast strains which had been pre-irradiated with U.V. light. U.V.-irradiated or non-irradiated fibroblasts were infected with either non-irradiated or irradiated Ad2, and at 48 hours after infection cells were examined for the presence of viral structural antigens (Vag) using immunofluorescent staining. Normal levels of UVER (i.e. 2-4 fold) of U.V.- and of gamma-irradiated Ad 2 were detected in 2 CS strains (CS IBE and CS 3BE), 2 XP complementation group A strains (XP 12BE and XP 25RO), and 2 XP complementation group D strains (XP 5BE and XP 6BE), although the U.V. doses to these mutant cells which resulted in peak UVER values (0 . 2 Jm-2 for XP 25RO, 0 . 14 Jm-2 for XP 12BE, 0 . 8 Jm-2 for XP 5BE and XP 6BE, and 1 . 6-5 . 0 Jm-2 for CS 1BE and CS 3BE) were considerably lower than those yielding peak UVER in normal strains (10-15 Jm-2). XP variant strains (XP 4BE and XP 115LO), however, showed substantially lower levels of UVER than normal strains.     

The extensibility of the plantar fascia influences the windlass mechanism during human running

The arch of the human foot is unique among hominins as it is compliant at ground contact but sufficiently stiff to enable push-off. These behaviours are partly facilitated by the ligamentous plantar fascia whose role is central to two mechanisms. The ideal windlass mechanism assumes that the plantar fascia has a nearly constant length to directly couple toe dorsiflexion with a change in arch shape. However, the plantar fascia also stretches and then shortens throughout gait as the arch-spring stores and releases elastic energy. We aimed to understand how the extensible plantar fascia could behave as an ideal windlass when it has been shown to strain throughout gait, potentially compromising the one-to-one coupling between toe arc length and arch length. We measured foot bone motion and plantar fascia elongation using high-speed X-ray during running. We discovered that toe plantarflexion delays plantar fascia stretching at foot strike, which probably modifies the distribution of the load through other arch tissues. Through a pure windlass effect in propulsion, a quasi-isometric plantar fascia''s shortening is delayed to later in stance. The plantar fascia then shortens concurrently to the windlass mechanism, likely enhancing arch recoil at push-off.     

Influence of ashing techniques on the analysis of trace elements in animal tissue

A multitude of methods exists at present for the solubilization of biological tissues for atomic absorption analysis. We have examined several common methods of wet ashing using NBS bovine liver in order to determine which acids, acid combinations, or bases should be used as digesting agents for accurate and precise measurement of iron, copper, zinc, and manganese. Nitric acid proved to be the most effective wet ashing agent. With nitric acid, mean concentrations for iron, copper, and zinc differed from NBS certified values by less than 1.5% while those for manganese differed by 4%.     

Aerobic glycolysis of bone and cartilage: The possible involvement of fatty acid oxidation

The apparent paradox of aerobic glycolysis has been investigated in bone and in cartilage. A new cytochemical procedure for hydroxyacyl dehydrogenase (HOAD) activity showed that the maximal activity of this enzyme in both tissues was equivalent to the maximal activity of glyceraldehyde 3-phosphate dehydrogenase (GAPD). The sum of these activities gave a measure of the maximum amount of acetyl-coenzyme A that could be produced. In these tissues, but not in liver which does not exhibit aerobic glycolysis, this summed value exceeded the maximal activity of succinate dehydrogenase (SDH). Consequently, it suggested that where fatty acid oxidation is sufficient to supply all the acetyl-coenzyme A required for the Krebs' cycle, that derived from fatty acid oxidation may inhibit pyruvate dehydrogenase causing accumulation of pyruvate which must be converted to lactate if pentose-shunt activity is to be maintained.     

Parental effects on inbreeding depression in a beetle with obligate parental care

Inbreeding depression occurs when individuals who are closely related mate and produce offspring with reduced fitness. Although inbreeding depression is a genetic phenomenon, the magnitude of inbreeding depression can be influenced by environmental conditions and parental effects. In this study, we tested whether size-based parental effects influence the magnitude of inbreeding depression in an insect with elaborate and obligate parental care (the burying beetle, Nicrophorus orbicollis). We found that larger parents produced larger offspring. However, larval mass was also influenced by the interaction between parental body size and larval inbreeding status: when parents were small, inbred larvae were smaller than outbred larvae, but when parents were large this pattern was reversed. In contrast, survival from larval dispersal to adult emergence showed inbreeding depression that was unaffected by parental body size. Our results suggest that size-based parental effects can generate variation in the magnitude of inbreeding depression. Further work is needed to dissect the mechanisms through which this might occur and to better understand why parental size influences inbreeding depression in some traits but not others.     

Rethinking AIDS

AIDS and Intravenous Drug Use: The Influence of Morality, Politics, Social Science, and Race in the Making of. Tragedy. M. Daniel Fernando. Westport, CT: Praeger Publishers, 1993.167 pp.