The blood antioxidant defence capacity during intermittent hypoxic training in elite swimmers.

The main objective of this study was to examine the chronic effect of simulated intermittent normobaric hypoxia on blood antioxidant defence capacity in swimmers. The study included 14 male and 14 female competitive swimmers performing part of land training under simulated intermittent normobaric hypoxia (O2 = 15.5%) or in normoxia. Land interval training took place twice per week, with a total of 8 training units during the study, performed with individualized intensity. The activities of blood antioxidant enzymes did not change significantly during the first and last training unit in the hypoxic and normoxic group. However, when comparing individual variables a significant effect of exercise was observed on GPx an CAT activities, whereas training units significantly differentiated GPx and GR activities. The oxygen conditions and gender had a significant influence on CAT activity. The total antioxidant capacity was not significantly affected. Only in male swimmers from the hypoxic group did the training significantly increase resting levels of MDA. In conclusion, training in normobaric hypoxia was not an adequate stimulus for the excessive response of the antioxidant defence system, despite increased oxidative stress in these conditions.

Blood antioxidant status in road cyclists during progressive (VO2max) and constant cyclist intensity test (MLSS).

AIM: The aim of the study was to evaluate the effect of two different cycling intensities on the blood antioxidant status in seven road cyclists male (M) (age 25.6±4.9 years; height 1.8±0.0 m; body mass 72.4±3.4 kg, and VO2max 66.8±8.9 mL*kg-1*min-1) and six road cyclists females (F) (age 26.5±2.5 years; height 1.67 ±0.01 m; body mass 56.5±5.3 kg; and VO2max 57.2±4.1 mL*kg-1*min-1). METHODS: The experiment was carried out with two tests: a progressive test (VO2max) (TP), and a 30-minute submaximal steady state test (TMLSS). The activity of superoxide dismutase, catalase (CAT), glutathione peroxidase, glutathione reductase, and creatine kinase, and the concentration of uric acid, reduced glutathione, malondialdehyde (MDA), blood lactate as well as total antioxidant potential, were assayed. RESULTS: Exercise significantly differentiated the activity and level of antioxidants. In both tests, after exercise a significant increase of CAT (P≤0.05) and CK (P≤0.05) activity was observed, as well as MDA (P≤0.05) level. CONCLUSION: It was demonstrated that neither the type of test (TP, TMLSS) nor the sex of the subjects exerted significant influence upon the activity of antioxidant enzymes and the level of low molecular weight antioxidants. Due to the workload in road cycling, where an average race or stage lasts a few hours, the 30-minute test was probably too weak a stimulus for the organism to disturb the pro- and antioxidative homeostasis.

Long-term cadmium exposure accelerates oxidant injury: significance of bound/free water states during long-term metal stress.

Lepidium sativum (cress) and Lycopersicon esculentum (tomato) plants were grown in peatlite in controlled environments with or without long-term (4 weeks) cadmium stress (Cd) (100 micrograms/ml every fourth day) and with a single exposure (6 hr at 35 parts per hundred million (pphm)) or no exposure to the oxidant ozone (O3). Cress plants which received Cd wilted faster during O3 exposure and became a gray-green color by the end of a 6-hr O3 exposure. Those receiving O3 alone also wilted but were normal in color during wilting. Leaf water content (percentage) significantly declined in both O3 + Cd- and O3-treated plants. However, leaves after Cd + O3 exposure were severely dessicated and necrotic, whereas O3-treated plants recovered their water content completely but had some injury. Increased stomatal aperture in cress but not tomato before O3 exposure and significantly lower water content at 1 and 24 hr after the end of O3 exposure were associated with the higher Cd content of leaves before and subsequent to O3 exposure. These factors contributed to a greater injury and cell death observed in the leaves of combined cadmium-oxidant stress. Dielectric properties of Thlaspi arvense (field penny cress) leaves grown at continuous exposure to Cd and/or nickel (Ni) indicated that there were measurable differences between metal-containing vs control leaves with regard to bound/unbound water status. This indicated that there was more free water under metal stress, and that the bound water content significantly declined in the leaves of these plants.

Plaque assay and replication of Tipula iridescent virus in Spodoptera frugiperda ovarian cells.

A plaque assay was developed for the study of Tipula iridescent virus (TIV) replication using a cell line derived from the fall army worm Spodoptera frugiperda (Sf9). Infection and plaque formation were monitored with time by phase contrast microscopy, video and fluorescent light microscopy. Structure of virions, viroplasmic centres and organelles of infected cells were examined by transmission electron microscopy (TEM). After 4 h postinfection, plaques were visibly detected within the cell monolayer by the presence of localized cell damage and production of numerous vesicular-like cytoplasmic structures. Quantitation of virions present per A260 unit of TIV preparation was determined by TEM. The number of visible plaques corresponded to virus concentration and 1 A260 produced approximately 10(5) plaques. DNA hybridization analysis revealed no gross differences in genomic DNA from TIV propagated in either Sf9 cells or wax moth Galleria mellonella larvae. These findings indicate that Sf9 is permissive for replication of TIV and superior by some parameters to other cell lines currently in use for the study of host cell/TIV interactions.

Transfer of acipimox across the isolated perfused human placenta.

The placental transfer of the new lipid-lowering agent, acipimox was investigated in the isolated perfused human placenta. Placentas obtained at caesarean section were perfused for 120 min, with both maternal and fetal circuits in closed recycling mode. Acipimox was added to either the maternal circuit alone (five experiments) or to both maternal and fetal circuits simultaneously (five experiments) to achieve initial concentrations of 5 micrograms/ml. Antipyrine (20 micrograms/ml) and l-(14C)-leucine (250 microM) were added in like fashion as reference compounds. Two hours after addition to the maternal circuit alone antipyrine was close to equilibrium across the placenta, but equilibration of acipimox was incomplete (fetal/maternal ratio = 0.58 +/- 0.11). Maternal to fetal placental clearance of acipimox (0.80 +/- 0.18 ml/min) was 25 per cent of antipyrine clearance. After simultaneous administration to both maternal and fetal circuits the l-(14C)-leucine fetal/maternal ratio was 1.44 +/- 0.13 at 120 min, whereas maternal and fetal concentrations of acipimox and antipyrine were at equilibrium for the duration of the experiment (fetal/maternal ratio of acipimox at 120 min = 1.10 +/- 0.06). This study shows that acipimox is transferred across the human placenta by diffusion at a slow rate. The low permeability of the placenta may afford some protection to the fetus from acipimox administered to the mother in vivo.

Disposition of the diastereoisomers quinine and quinidine in the ovine fetus.

The disposition of the diastereoisomers quinine and quinidine was investigated in the near-term pregnant ewe. Five sheep were administered quinine and quinidine separately in random order by a combination of bolus and 30-h iv infusion. On a subsequent occasion, four of the five sheep were also administered the two drugs simultaneously. After separate dosage, systemic clearance of quinine tended to be greater than that of quinidine (714 +/- 299 versus 422 +/- 146 mL/min, p = 0.08). Maternal renal clearance exhibited no stereoselectivity and represented less than 2% of total clearance. Simultaneous administration did not alter the disposition of either drug in the mother. After separate dosage, fetal total concentrations (Cf) of quinine and quinidine were substantially lower than maternal total concentrations, as reflected in Cf:Cm ratios of 0.15 +/- 0.06 versus 0.10 +/- 0.08, respectively. Similarly, fetal unbound concentrations (Cfu) were substantially lower than maternal unbound concentrations (Cmu; Cfu/Cmu = 0.46 +/- 0.09 for quinine and 0.23 +/- 0.09 for quinidine). This indicates the presence of fetal elimination of both isomers. Fetal renal clearances of quinine and quinidine were similar (0.34 +/- 0.24 mL/min versus 0.38 +/- 0.24 mL/min) and less than that of endogenous creatinine, indicating the absence of net renal tubular secretion. After simultaneous dosage of quinine and quinidine, Cf:Cm (0.48 +/- 0.24 and 0.31 +/- 0.19, respectively) and Cfu:Cmu (0.73 +/- 0.14 and 0.52 +/- 0.20, respectively) were greater than for separate dosages. Fetal renal clearance of both drugs was unchanged, suggesting that the higher Cfu:Cmu ratios after simultaneous dosage were due to mutual inhibition of the fetal metabolism of these drugs.

Selective sensitivity to methylmercury of specific cell aggregates and validity of the "nurse" cell concept.

Meristematic cells of carrot (Daucus carota--Ca68-10) were grown in a heterogeneous suspension culture in the absence of (2,4-dichlorophenoxy)acetic acid in 71-V medium in the dark. Freshly inoculated cell cultures were treated daily with methyl mercury for the first 4 days and harvested on Day 7. The cultures were separated (by selective filtration) into groups of aggregates varying in size from 44 to 900 microns. Methyl mercury severely decreased the cell mass of the dominant (300-microns) fraction. When separate aggregates were cultured (44 to 900 microns) and treated as before, the inhibition of the 300 microns fraction was more evident. Separately cultured cell groups of 200- or 300-microns size developed into larger heterogeneous populations and contained the dominant 300-microns size group which was the most sensitive to methyl mercury. Other cell groups (900-, 500-, and 44-microns) failed to produce a large heterogeneous cell population when cultured separately. Without the 300-microns-sized aggregate, neither the whole culture nor the separate aggregates culture (900, 500, or 44 microns) could survive, suggesting the "nurse" cell role of the 300-microns cell group.

The interaction between cells in different phases of the cell cycle and aminocarb.

Synchronous cultures of Chlamydomonas segnis Ettl. were treated with aminocarb (0.5, 5.0, 10.0, or 50.0 micrograms ml-1) at each specific phase of the cell cycle, namely, G1, S, G2, and M phases. The subsequent effects of some macromolecular products were assayed at the end of the M phase. Aminocarb treatments of 0.5 microgram ml-1 were at the no effects level on the parameters monitored. However, the higher concentrations of aminocarb tested, namely, 5, 10, and 50 micrograms ml-1, dramatically affected not only macromolecular syntheses but also some cell cycle events. Algistatic and algicidal effects were obtained with some treatments.

Biological and NMR markers for cancer.

The search for a universal tumor marker continues. Present markers range from tumor products (polyamines, glycoproteins, peptides, hormones or carbohydrate-linked markers) to reaction products produced by the host tissues during tumor invasion. Techniques used to identify them include the classical methods of histology and cytochemistry as well as the more recent radioimmunoassay and metabolic probes. The in vivo techniques of increasing use for patient monitoring are MRS (magnetic resonance spectroscopy) and MRI (magnetic resonance imaging). The efficiency of some markers and statistical methods used in analyzing data are discussed, as are the ethical problems surrounding the use of new testing methods. Recent developments in MRI and MRS, marker elucidation, and evidence for a new autocrine differentiation-inhibiting factor (ADIF) are reviewed. Future needs and approaches focus on greater utilization of indicators of the preneoplastic state and of risk to cancer, as well as more careful attention to statistical analysis.

Ontogeny of fetal renal organic cation excretion: a study with cimetidine and ranitidine during the latter half of gestation in the pregnant ewe.

The organic cation cimetidine undergoes renal tubular secretion in the near-term ovine fetus. We investigated the ontogeny of renal tubular secretion of organic cations in the fetus from 80 days of gestation (term = 145). Sixteen sheep were administered both cimetidine and ranitidine in random order by a combination of bolus and i.v. infusion to achieve steady-state plasma concentrations of 1000 to 2000 ng/ml. A further two sheep received cimetidine only. Steady-state plasma concentrations were reached within 2 to 3 hr. Creatinine was used as a marker of glomerular filtration rate. Maternal renal clearance of cimetidine (0.51 +/- 0.18 l/min) and ranitidine (0.54 +/- 0.14 l/min) were not correlated with the period of gestation. Cimetidine/creatinine and ranitidine/creatinine renal clearance ratios were higher than unity being 5.48 +/- 1.91 and 5.65 +/- 1.18, respectively. Fetal creatinine renal clearance increased exponentially with gestational age (r2 = 0.577, P less than .001). Fetal renal clearance of both cimetidine and ranitidine also increased exponentially with gestational age, this trend being more clear-cut for cimetidine (r2 = 0.582, P less than .001) than for ranitidine (r2 = 0.254, P = .046). The rates of increase for cimetidine and ranitidine were similar to that for creatinine (P greater than .05). At 80 days, cimetidine/creatinine and ranitidine/creatinine renal clearance ratios (3.0 and 4.4, respectively) were higher than unity and did not increase further during the remainder of gestation. Therefore, the ovine fetus possesses an efficient tubular secretory pathway for organic cations by 80 days of gestation.(ABSTRACT TRUNCATED AT 250 WORDS)