Kinetic study of time-dependent fixation of UVI on biochar.

Biochar, a by-product from the production of biofuel and syngas by gasification, was tested as a material for adsorption and fixation of UVI from aqueous solutions. A batch experiment was conducted to study the factors that influence the adsorption and time-dependent fixation on biochar at 20°C, including pH, initial concentration of UVI and contact time. Uranium (UVI) adsorption was highly dependent on pH but adsorption on biochar was high over a wide range of pH values, from 4.5 to 9.0, and adsorption strength was time-dependent over several days. The experimental data for pH>7 were most effectively modelled using a Freundlich adsorption isotherm coupled to a reversible first order kinetic equation to describe the time-dependent fixation of UVI within the biochar structure. Desorption experiments showed that UVI was only sparingly desorbable from the biochar with time and isotopic dilution with 233UVI confirmed the low, or time-dependent, lability of adsorbed 238UVI. Below pH 7 the adsorption isotherm trend suggested precipitation, rather than true adsorption, may occur. However, across all pH values (4.5-9) measured saturation indices suggested precipitation was possible: autunite below pH 6.5 and either swartzite, liebigite or bayleyite above pH 6.5.

In vitro conservation of embryogenic cultures of date palm using osmotic mediated growth agents.

This study was carried out to investigate the effect of mannitol, sorbitol and sucrose as osmotic agents on in vitro conservation of embryogenic cultures of date palm (Phoenix dactylifera, L.) Bartamoda and Sakkoty cultivars. Embryogenic cultures was obtained using MS medium supplemented with 10 mg/l 2,4-dichlorophenoxy acetic acid (2,4-D) and 3 mg/l isopentenyl adenine (2iP). Among the three types of osmotic substances used for slow growth conservation, sucrose at all concentrations gave the highest percentage of survival with Sakkoty cultivar. However, addition of 40 g/l or 60 g/l mannitol and 20 g/l sorbitol showed the highest percentage of survival percentage with Bartamoda cultivar. The different sucrose concentrations caused higher numbers of germinated embryos of the two cultivars compared with mannitol or sorbitol. Also, the number of germinated embryos was increased with increasing the storage periods till the ninth month. Genetic stability was determined using random amplified polymorphic DNA (RAPD) analysis. There were no clear genetic differences between the two osmotic agents used for preservation. The preserved cultures of Sakkoty cultivar gave the high percent of similarity while Bartamoda cultivar gave low percent of similarity. From the obtained results we can recommend using 40 g/l mannitol or 20 g/l sorbitol for in vitro preservation of Bartamoda cultivar of date palm and 20 g/l of sucrose for Sakkoty cultivar.

Effects of propofol and isoflurane on haemodynamics and the inflammatory response in cardiopulmonary bypass surgery.

Cardiopulmonary bypass (CPB) causes reperfusion injury that when most severe is clinically manifested as a systemic inflammatory response syndrome. The anaesthetic propofol may have anti-inflammatory properties that may reduce such a response. We hypothesised differing effects of propofol and isoflurane on inflammatory markers in patients having CBR Forty patients undergoing elective CPB were randomised to receive either propofol or isoflurane for maintenance of anaesthesia. CRP, IL-6, IL-8, HIF-1α (ELISA), CD11 and CD18 expression (flow cytometry), and haemoxygenase (HO-1) promoter polymorphisms (PCR/electrophoresis) were measured before anaesthetic induction, 4 hours post-CPB, and 24 hours later. There were no differences in the 4 hours changes in CRP, IL-6, IL-8 or CD18 between the two groups, but those in the propofol group had higher HIF-1α (P = 0.016) and lower CD11 expression (P = 0.026). After 24 hours, compared to the isoflurane group, the propofol group had significantly lower levels of CRP (P < 0.001), IL-6 (P < 0.001) and IL-8 (P < 0.001), with higher levels CD11 (P = 0.009) and CD18 (P = 0.002) expression. After 24 hours, patients on propofol had increased expression of shorter HO-1 GT(n) repeats than patients on isoflurane (P = 0.001). Use of propofol in CPB is associated with a less adverse inflammatory profile than is isofluorane, and an increased up-regulation of HO-1. This supports the hypothesis that propofol has anti-inflammatory activity.

Airborne 222Rn concentration in an Egyptian village.

The indoor radon concentration in a typical Egyptian village in Delta was measured in 50 houses during summer 1999 and winter 2000. This survey was done using three different types of charcoal canisters: 4" open-faced, 2.75" open-faced, and 2.75" diffusion barrier. The average winter to summer ratio was 2.1 and 1.2 for open rooms and closed rooms, respectively, in clay buildings, while it was 0.8 and 1.0, respectively, in concrete buildings. The seasonal variations of radon concentration as well as the effect of building materials were discussed.

The effect of dietary linoleic acid on blood pressure and erythrocyte sodium transport.

The influence of an increase in the polyunsaturated fat linoleic acid on blood pressure and erythrocyte membrane sodium transport was investigated in normotensive first degree relatives of hypertensive patients and controls by the double blind administration of safflower oil or paraffin oil (placebo) capsules for four weeks separated by a four week washout period. Systolic blood pressure fell in the controls with linoleic acid supplementation but there was no significant change in total sodium efflux rate constant. When the pattern of response was compared the changes in supine systolic blood pressure, plasma renin activity, total and ouabain-sensitive sodium efflux rate constant were significantly different in the controls compared to the relatives. These results show that dietary linoleic acid supplementation may have effects on ionic fluxes across cell membranes and cause a modest fall in blood pressure. In addition, since the response to the change in fat intake was different in the relatives and the controls, this provides further evidence of differences in the physicochemical structure of the plasma membrane in hypertensive subjects and their offspring.

Effects of manipulation of sodium balance on erythrocyte sodium transport.

The effects of changing sodium balance on blood pressure (BP) and erythrocyte sodium transport were investigated in normotensive first-degree relatives of hypertensive patients and control subjects randomised to receive low and high salt diets for two weeks, separated by a two week washout period. Changing from high to low salt intake produced a significant fall in standing diastolic pressure (DBP) in control subjects but not in the offspring of hypertensive patients. In both groups erythrocyte sodium efflux was not changed significantly by either manoeuvre, but the relatives had a significantly higher ouabain insensitive sodium efflux rate constant on both the low and the high salt diet compared to the controls (P less than 0.05). These results are not in keeping with the hypothesis which suggests the release of a humoral sodium pump inhibitor in response to sodium loading but lend support to the view that there is a disturbance of membrane permeability to sodium in subjects genetically prone to hypertension.

Effects of changes in sodium balance on leucocyte sodium transport: qualitative differences in normotensive offspring of hypertensives and matched controls.

To investigate the effects of changes in sodium balance on blood pressure and leucocyte sodium transport, normotensive first-degree relatives of hypertensive patients and control subjects were randomized to receive low- and high-salt diets for 2 weeks, separated by a wash-out period of 2 weeks. High-salt intake failed to alter blood pressure, whereas the low-salt diet produced significant falls in standing pressures in both groups. In the control subjects leucocyte sodium efflux was not changed by either manoeuvre, but in the relatives low-salt diet stimulated ouabain-insensitive sodium efflux rate constant. There was a significant qualitative difference in the pattern of response of total efflux rate constant to the two dietary periods between the two groups of subjects. These data are not compatible with the release of a humoral sodium pump inhibitor in response to sodium-induced volume expansion, and lend support to a disturbance of membrane permeability to sodium in subjects genetically prone to hypertension.

Cell membrane handling of sodium, sodium balance, and blood pressure.

A variety of abnormalities in cell membrane cation handling have been reported in hypertension. It is not known whether abnormal transport serves as a marker of an underlying disturbance in cell membrane function or whether one or more of the abnormal transport processes participate directly in the sequence of events that cause hypertension. One critical area is the response of membrane sodium transport to salt depletion and loading. To elucidate a possible relationship between changes in sodium balance, membrane cation transport, and blood pressure, we studied the effect of salt depletion and loading in two cells from two separate species--the rat thymocyte and the human white blood cell. In each, severe salt depletion significantly reduced ouabain-sensitive sodium efflux, while salt loading produced a non-significant increase. No significant changes in the sodium efflux rate constant were observed in thymocytes from Okamoto-Kyoto spontaneously hypertensive rats or from rats with Goldblatt one-kidney, one-clip or deoxycorticosterone-salt hypertension when they were compared with appropriate controls. However, both Okamoto-Kyoto hypertensive rats and Kyoto controls showed a highly significant fall in the sodium efflux rate constant with age. These findings indicate that the reduction in sodium pumping observed in hypertensive human patients is not attributable directly or indirectly to salt excess, since in the two species studied reduced sodium pumping was a physiological response to salt depletion. Further, altered membrane transport of sodium may reflect factors that affect cell composition (such as age) rather than participate directly in the pathogenesis of hypertension.