Liver peroxisomes in newborns from clofibrate-treated rats. II. A biochemical study of the recovery period.

The fatty-acyl-CoA beta-oxidation (FAO) and catalase activities, as well as membrane fluidity of liver peroxisomes of newborns from normal and clofibrate-treated rats were studied during the recovery period, ie, throughout the first week of postnatal life. In the test animals the enzyme activities, which are significantly higher than controls at birth return to normal levels showing a somewhat different time course with FAO rapidly decreasing to control values within three days but with catalase still higher than controls at day 6. The half-life and degradation rate (Kd) of FAO are identical to those calculated by us for the whole organelles and to those reported by others for total catalase in normal or clofibrate-treated adult animals in the presence of catalase inhibitors. Soluble catalase shows turnover values which are similar though not identical to those of FAO, while total catalase has a very long half-life and a low Kd. Peroxisomal membrane fluidity, as determined by fluorescence anisotropy of 1-anilinonaphthalene-8-sulfonate (ANS) bound to purified peroxisomal fractions is higher in tests than in controls, recovering normal values within 6 days. Our results demonstrate that liver peroxisomes of rats prenatally exposed to clofibrate return to control conditions within about 1 week. The turnover parameters of enzymes and the membrane fluidity values are discussed in terms of disposal mechanism(s) for the excess of induced peroxisomes.     

Semisynthetic preparation of N-glycolylneuraminic acid containing GM1 ganglioside: chemical characterization, physico-chemical properties and some biochemical features

N-Glycolylneuraminic acid containing GM1, GM1(NeuGc), was prepared by semisynthetic procedure. The procedure makes use of GM1 ganglioside deacetylated at the level of sialic acid residue (deAc-GM1) and of 1,3-dioxalan-2,4-dione. DeAc-GM1 is prepared from GM1 by alkaline hydrolysis in the presence of tetramethylammonium hydroxide and the glycolylating compound by reaction of glycolic acid with phosgene in dioxane, followed by cyclization under vacuum. Mass spectrometric and nuclear magnetic resonance spectroscopy analyses clearly indicated the presence, in the neosynthesized ganglioside of a glycolic group in the sialic acid residue. Laser-light scattering measurements show that GM1(NeuGc) aggregates in aqueous media being present in solution as micelles with a molecular weight of 576,000 and a hydrodynamic radius of 62.4 A as determined at 25 degrees C. GM1(NeuGc) promotes neurite outgrowth in N-2a cells to a similar degree as GM1(NeuAc), but shows different behaviour under treatment with sialidase from Arthrobacter ureafaciens.     

Ornithine decarboxylase, transglutaminase, diamine oxidase and total diamines and polyamines in maternal liver and kidney throughout rat pregnancy.

Ornithine decarboxylase (ODC; EC 4.1.1.17), transglutaminase (EC 2.3.2.13), diamine oxidase (DAO; EC 1.4.3.6) and total di- and poly-amines were studied in rat liver and kidney cortex throughout pregnancy. In liver, ODC activity exhibited two major peaks (4.5-5 times the control activities) on days 15 and 17. Also putrescine and spermidine increased biphasically (3-4-fold), but no variation in spermine content was observed. Transglutaminase activity showed slight variations only near the end of gestation. In kidney, ODC activity did not fluctuate significantly during pregnancy, whereas both transglutaminase activity and putrescine content showed three major increases, in very early, middle and late pregnancy. No significant variations in spermidine and spermine were observed. In both organs, DAO activity, very low or undetectable until day 10, dramatically increased (10- and 20-fold in kidney and liver respectively) in the second half of pregnancy, reaching maxima on days 16-17 and 19. The results obtained for transglutaminase, ODC and total di- and poly-amines are interpreted on the basis of hyperplastic and hypertrophic events in the liver and kidney respectively. The behaviour of DAO suggests that the enzyme plays an important role in the control of intracellular diamine concentration.     

UVB radiation affects the mobility of epidermal growth factor receptors in human keratinocytes and fibroblasts

Growth factor receptors transmit biological signals for the stimulation of cell growth in vitro and in vivo and their autocrine stimulation may be involved in tumorigenesis. It is therefore, of great value to understand receptor reactions in response to ultraviolet (UV) light which certain normal human cells are invaribly exposed to during their growth cycle. UV irradiation has recently been shown to deplete antioxidant enzymes in human skin. The aims of the present study were a) to compare the lateral mobility of epidermal growth factor receptors (EGF-R) in cultured human keratinocytes and human foreskin fibroblasts, b) to investigate effects of ultraviolet B radiation on the mobility of EGF-R in these cells, and c) study the response of EGF-R on addition of antioxidant enzymes. The epidermal growth factor receptors were labeled with rhodaminated EGF, the lateral diffusion was determined and the fraction of mobile EGF-R assessed with the fluorescence recovery after photobleaching (FRAP). We found that human keratinocytes display a higher basal level of EGF-R mobility than human skin fibroblasts, viz. with diffusion coefficients (D ± standard error of the mean, SEM) of 4.2±0.2 × 10^–10 cm²/s, and 1.8±0.2 × 10^–10 cm²/s, respectively. UVB-irradiated fibroblasts showed an almost four-fold increase in the diffusion coefficient; D was 6.3±0.3 × 10^–10 cm²/s. The keratinocytes, however, displayed no significant increase in receptor diffusion after irradiation; D was 5.1±0.8 × 10^–10 cm²/s. In both cell types the percentage of EGF-R fluorescence recovery after photobleaching, i.e. the fraction of mobile receptors, was significantly increased after irradiation. In keratinocytes it increased from 69% before irradiation to 78% after irradiation. Analogous figures for fibroblasts were 61% and 73%. The effect of UVB on fibroblast receptors was abolished by prior addition of superoxide dismutase (SOD) and catalase (CAT). It is concluded that UVB radiation of fibroblasts and keratinocytes can affect their biophysical properties of EGF-R. The finding that addition of antioxidant enzymes prevented the UVB effect in fibroblasts may indicate the involvement of reactive oxygen metabolites.Abbreviations CAT Catalase - D Lateral diffusion coefficient - EDTA Ethylenediaminetetraacetic acid - EGF Epidermal growth factor - E-MEM Eagle's minimum essential medium - FCS Fetal calf serum - FRAP Fluorescence recovery after photobleaching - KRG Krebs-Ringer phosphate buffer - PBS Phosphate-buffered saline - R Mobile fraction - ROS Reactive oxygen species - SEM Standard error of the mean - SOD Superoxide dismutase - UVA Ultraviolet light-A (315-400 nm) - UVB Ultraviolet light-B (280-315 nm)     

High-resolution mapping of a linkage group on mouse chromosome 8 conserved on human chromosome 16Q

We have performed a high-resolution linkage analysis for the conserved segment on distal mouse Chromosome (Chr) 8 that is homologous to human Chr 16q. The interspecific backcross used involved M. m. molossinus and an M. m. domesticus line congenic for an M. spretus segment from Chr 8 flanked by phenotypic markers Os (oligosyndactyly) and e, a coat colormarker. From a total of 682 N₂ progeny, the 191 animals revealing a recombination event between these phenotypic markers were typed for 23 internal loci. The following locus order with distances in cM was obtained: (centromere)–Os–4.1–Mmp2–0.2–Ces1,Es1, Es22–1.2–Mt1,D8Mit15–2.2–Got2, D8Mit11–3.7–Es30–0.3–Es2, Es7–0.9–Ctra1,Lcat–0.3–Cdh1, Cadp, Nmor1, D8Mit12–0.2–Mov34–2.5–Hp,Tat–0.2–Zfp4–1.6–Zfp1,Ctrb–10.9–e. In a separate interspecific cross involving 62 meioses, Dpep1 was mapped together with Aprt and Cdh3 at 12.9 cM distal to Hp, Tat, to the vicinity of e. Our data give locus order for markers not previously resolved, add Mmp2 and Dpep1 as new markers on mouse Chr 8, and indicate that Ctra1 is the mouse homolog for human CTRL. Comparison of the order of 17 mouse loci with that of their human homologs reveals that locus order is well conserved and that the conserved segment in the human apparently spans the whole long arm of Chr 16. Received: 30 July 1996 / Accepted: 15 November 1996     

Simple and non-radioactive method for determination of sialyltransferase activity

A new, non-radioactive and cheap colorimetric method for determination of activity of sialyltransferases of various specifities using natural substrates based on 2-thiobarbituric acid assay is presented. The assay was tested with three different sialyltransferases (a-2,3 and a-2,6) and compared with the radioactive assay.     

Mechanical characterization of 3D printed mimic of human artery affected by atherosclerotic plaque through numerical and experimental methods

Biomechanics and Modeling in Mechanobiology - This paper proposes a novel experimental investigation based on 3D printing to validate numerical models for biomechanics simulations. Soft elastomeric...     

A randomized placebo-controlled study on high-dose oral algal docosahexaenoic acid supplementation in children with cystic fibrosis

Low plasma concentrations of docosahexaenoic acid (DHA) are reported in unsupplemented cystic fibrosis (CF) patients. Forty-one CF patients aged from 6 to 12 years were randomized to receive high-dose DHA (100 mg/kg/day in the first month and 1 g per day thereafter through a 12-month supplementation) or placebo (germ oil). Primary outcome was percentage change in plasma AA:DHA ratio. Secondary outcomes were changes in the number of pulmonary exacerbations compared to previous year, lung function, BMI, skinfold thicknesses, and body composition assessed by DXA and in serum concentrations of C-reactive protein, cytokines and vitamin (α-tocopherol and retinol). Compared to the control group plasma AA:DHA ratio decreased in the intervention group after 6 months (median percentage changes: ?73% in the intervention group vs. ?10% in the control group, P=0.001). No differences were detected between groups for secondary outcomes. Despite a decrease of the AA/DHA ratio, DHA supplementation for one year did not induce any significant biochemical and clinical improvement in CF patients.