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.

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.

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.

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.

The effects of plant-incorporated methylmercury on its distribution, excretion and demethylation patterns in the rat.

Rats were dosed once per os with either plant-incorporated or solution-radioactive methylmercury (MeHg). While whole-body retention did not change, the incorporation into some organs was approx. 2.5 X higher when administered Hg was in the plant-incorporated rather than in solution form. The only noticeable change in demethylation occurred in the cerebrum where MeHg:Hg ratios were 79:10 (plant-incorporated MeHg) and 65:24 (solution-MeHg). Between 5 to 7% of the total mercury was excreted in faeces and urine either in the inorganic (faeces) or organic (urine) forms. Mercury levels in mitochondrial and soluble fractions of cerebrum were noticeably lower with plant-MeHg than with solution-MeHg.

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.

Influence of maternal plasma protein binding on fetal unbound plasma concentration of propranolol in the pregnant ewe.

According to theory, for a drug of nonrestrictive, flow-limited clearance, a change during pregnancy of the unbound fraction (fu) of drug in maternal plasma should cause a change in steady-state unbound plasma drug concentration (Cu) in maternal plasma, which should also cause a change in fetal Cu. This theory was examined in 14 chronically cannulated, unanesthetized pregnant ewes in which 28 separate experiments were performed during the latter part of gestation. An initial bolus dose and 3-h constant rate infusion of propranolol were administered via the maternal jugular vein and steady-state maternal and fetal carotid arterial plasma total and unbound propranolol concentrations were measured. Fetal Cu (32 +/- 21 ng/mL) was significantly less than maternal Cu (78 +/- 52 ng/mL), due to previously demonstrated fetal hepatic extraction of propranolol. Notwithstanding fetal elimination, there was a significant correlation between fetal Cu and maternal Cu (r = 0.41, p less than 0.025). There was also a strong correlation between fetal Cu and the maternal unbound fraction of drug (fu; r = 0.75, p less than 0.001). We conclude that for propranolol, a drug of nonrestrictive, flow-limited clearance, changes in maternal fu can have a significant influence on fetal Cu, and therefore would be expected to influence the pharmacological effect of the drug in the fetus.

The fate of Cd, Cu, Ca, Zn, and Fe in rat during the recovery period following cessation of repeated exposure to Cd.

Cadmium was administered subcutaneously to male Wistar rats, 0.1 mL/rat in 0.9% saline 3 times a wk for 4 wk at 3 mg Cd/kg. Saline was administered to control animals in an equivalent manner, without Cd. After the end of the dosing period, the distribution and excretion of Cd, Cu, Ca, Zn, and Fe were observed in some organs and excreta for 35 d (1, 7, 14, 21, 28, and 35 d). Cadmium dosing caused significant disturbances in the metabolism of Zn, Cu, Fe, and Ca, especially during the recovery period. Growth in Cd-dosed animals did not accelerate, even after 5 wk of recovery. There was evidence of mobilization of some elements among organs. Accumulation of Cd occurred in liver, kidney, and spleen during dosing, and during the recovery period it was retained in kidney and testes (for 2 wk) and cleared steadily in liver and RBC (for 5 wk), but increased in spleen (first 3 wk). The pattern of Cd excretion was closely associated with the binding of Cd with metallothioneins in kidney and liver for the first 21 and 7 d, respectively. This was associated with the excretion of Cd-metallothioneins (Cd-MT) in urine from d 1 to 21 during recovery. Cadmium caused higher Ca accumulations in testes and liver, which were probably associated with the lesions observed in these organs. Significant increases of Cu (in kidney d 7) and Fe (in liver) were observed during recovery. Furthermore, significant reductions of Cu and Fe were found in plasma, spleen, and RBC (after 5 wk) and kidney, spleen, and testes (on d 7), and blood (after 5 wk).

Methyl mercury toxicity in plant cultures: modification of resistance and demethylation by light and/or 2,4-dichlorophenoxyacetic acid.

Cultures of Daucus carota, Ca-68-10, and Lactuca sativa, Le-67, were grown at increasing methyl mercury (MeHg) concentrations ranging from initial doses of 0.05 to 5.0 micrograms/ml per day for 4 days with or without 0.15 microgram/ml 2,4-dichlorophenoxyacetic acid (2,4-D) in the presence or absence of light. The presence of 2,4-D interacted with light synergistically in the expression of MeHg toxicity within the whole range of concentrations. Demethylation patterns increased or decreased depending on the species, the 2,4-D concentration in the medium, and methyl mercury concentration used in the treatment. Lettuce was more sensitive to this interaction than carrot. In lettuce, the presence of 2,4-D in the light lowered the concentration of total Hg (or MeHg) required to reduce growth by 50%, about 13 times relative to that in the dark (i.e., it sensitized the cells). In the absence of 2,4-D the pattern was reversed. In carrot the pattern was similar but less pronounced. This suggests that, in these cell populations, MeHg toxicity is partly a hormone-mediated and light-sensitive event.

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.

Relative resistance of and delayed toxicity in undifferentiated plant cells to methyl mercury.

Meristematic cells of carrot (Daucus carota L., Ca68-10) and lettuce (Lactuca sativa L., LE-67) cultured in 71-V medium (with 0.15 microgram/ml 2, 4-D) were given one initial dose (0.0001, 0.001, or 0.01 microgram/ml) of methyl mercury (MeHg) at 0 hr, cultured for 288 hr. and then subcultured for 4 weeks. In another experiment, MeHg was added in four daily doses (0.05, 0.10, 0.50, 1.0, 2.5, or 5.0 micrograms/ml) starting at 72 hr for 120 hr and then subcultured for 168 hr. The resulting 50% growth reduction (Gr50) levels were high--1570 and 540 micrograms Hg/g dry wt for carrot and lettuce, respectively. Methyl mercury was taken up completely by cells but retention decreased at higher MeHg concentrations in the medium. The resistance of undifferentiated cells of both species to MeHg was markedly greater than that observed in multicellular plants. Cells derived from Hg-treated cultures did not recover their growth potential when subcultured in Hg-free medium. The Gr50 levels were lowered during successive subculturing in both carrot (50 micrograms Hg/g) and lettuce (10 micrograms Hg/g), indicating increased sensitivity to residual Hg in cells. This effect depended on the initial Hg concentration and on the number of cell divisions. At low MeHg concentrations, it was observed in cells 12 generations after one initial dose of 0.01 microgram/ml MeHg.

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.

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.

Effects of heavy metals absorbed from water on the laser-induced fluorescence in Elodea densa.

Comparative rates of absorption of copper, lead, cadmium, nickel, tin, and inorganic and methylmercury ions from water by Elodea densa were measured. Methylmercury, at relatively low tissue concentrations, was the only ion that quenched the laser-induced fluorescence.

Effects of methyl mercury on arrays of microtubules and macromolecular synthesis in Daucus carota cultures.

Cell suspension cultures of Daucus carota were exposed to methyl mercury at concentrations between 0 and 6 micrograms/ml for 1, 3, or 24 hr. Microtubule arrays exhibited no detectable disruption (as compared with controls) when treated with 1, 2, and 3 micrograms/ml methyl mercury. Disorganization of microtubules did occur at higher concentrations (4-6 micrograms/ml) in a concentration/time-dependent manner. No recovery of microtubule arrays was evident when cells were placed in methyl mercury-free medium for up to 7 days. Analyses of soluble protein and carbohydrate content, dry weight, and cell viability (reducing capacity) indicate that methyl mercury exposure has inhibitory effects on cell metabolism. The observed disruption of plant cell microtubules, induced by exposure to methyl mercury, may be secondary in response to an initial inhibition of synthetic pathways and membrane perturbations.

Demethylation and excretion of methyl mercury by the guinea pig.

Female guinea pigs were dosed po with 1.0 mg CH3 203Hg/kg as methylmercuric chloride, 10 times over a 3-week period. Tissue distribution, excretion, and accumulation of inorganic and organic mercury were studied. The highest concentration of mercury was found in the kidney. The greatest decreases of mercury levels were observed in the small bowel, red blood cells, liver, and cerebrum. The half-life of whole body clearance, based on a single compartment model, was 31.6 days. Mercury in the kidney, liver, and cerebrum was bound mainly by nuclear and soluble fractions. The highest ratio of inorganic to total mercury was seen in the kidney, 60% of this being as inorganic mercury. Excretion of mercury in the feces was measured throughout the experiment. The relationship of organic to inorganic mercury was relatively constant at about 1:3. Data on the effects of methyl mercury on tissue concentrations of zinc and copper show that the only change in the copper content was a marked increase in the kidney.

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.

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)

Effects of gestational age on the disposition of propranolol in pregnant sheep.

Maternal and fetal disposition of the beta adrenoceptor blocking drug, propranolol was examined in the pregnant sheep from day 95 to day 140 (term, 145 days) of gestation. Propranolol was administered to the mother (bolus dose, 1.5 mg/kg followed by an infusion of 1.2 mg/kg/hr over 3 hr) to achieve an average steady-state maternal total drug concentration of 600 ng/ml. Total steady-state maternal plasma propranolol concentration was 666 +/- 266 ng/ml, reflecting a 4-fold variation in maternal drug clearance and a 14-fold variation in binding. Neither maternal clearance nor binding showed a significant change with gestational age. Total plasma drug concentrations in the fetus increased significantly with gestational age (r = 0.58, P less than .05), due to a concomitant increase in binding (r = 0.66, P less than .01). Fetal steady-state unbound drug concentrations were 50% of those seen in the mother, indicating that the fetus is capable of irreversible elimination of the drug. This ratio did not change with gestational age, suggesting that the capacity of the fetus to eliminate propranolol does not increase detectably in the latter part of pregnancy. The significant correlation between maternal and fetal unbound drug concentrations indicates that a major determinant of fetal exposure to propranolol is the clearance of the drug by the mother.

Mechanism of triamterene transfer across the human placenta.

The diuretic, triamterene, had been regarded to be a drug which was actively transported by the placenta from fetus to mother. In the present study, the transfer of triamterene across the isolated perfused human placenta was examined. Placentas obtained at cesarean section were perfused for up to 2 hr from both maternal and fetal sides in either single-pass or recycling constant flow systems. In single-pass experiments, the placental clearance of triamterene (400 ng/ml) from mother to fetus or from fetus to mother was examined (n = 8). Antipyrine (20 micrograms/ml) and l-leucine (0.25 mM) were used as reference compounds. The transplacental clearance index (i.e., clearance relative to antipyrine clearance) of triamterene from mother to fetus (0.85 +/- 0.10) was similar to the clearance index from fetus to mother (0.74 +/- 0.08, P greater than .10), indicating rapid transfer across the placenta, but no active fetal to maternal transport. In contrast, the l-leucine clearance index from mother to fetus (0.62 +/- 0.05) was substantially greater than that from fetus to mother (0.27 +/- 0.03, P less than .01), consistent with active maternal to fetal transport. In recycling experiments (n = 5), with test compounds added in equal concentration to both maternal and fetal circuits, the equilibrium fetal/maternal perfusate concentration ratios were 1.41 +/- 0.02 for l-leucine and 0.98 +/- 0.01 for antipyrine. The slightly lower value for triamterene (0.92 +/- 0.02) probably reflected minor differences in protein binding between maternal and fetal circuits.(ABSTRACT TRUNCATED AT 250 WORDS)