Time-resolved relaxation and fragmentation of polycyclic aromatic hydrocarbons investigated in the ultrafast XUV-IR regime.

Polycyclic aromatic hydrocarbons (PAHs) play an important role in interstellar chemistry and are subject to high energy photons that can induce excitation, ionization, and fragmentation. Previous studies have demonstrated electronic relaxation of parent PAH monocations over 10-100 femtoseconds as a result of beyond-Born-Oppenheimer coupling between the electronic and nuclear dynamics. Here, we investigate three PAH molecules: fluorene, phenanthrene, and pyrene, using ultrafast XUV and IR laser pulses. Simultaneous measurements of the ion yields, ion momenta, and electron momenta as a function of laser pulse delay allow a detailed insight into the various molecular processes. We report relaxation times for the electronically excited PAH*, PAH+* and PAH2+* states, and show the time-dependent conversion between fragmentation pathways. Additionally, using recoil-frame covariance analysis between ion images, we demonstrate that the dissociation of the PAH2+ ions favors reaction pathways involving two-body breakup and/or loss of neutral fragments totaling an even number of carbon atoms.

Body composition and selected blood parameters in mice fed a combination of fibre and conjugated linoleic acid.

Feeding mice conjugated linoleic acid (CLA) reduces body fat. Soluble fibre decreases apparent lipid digestibility. The objective of the present study was to examine whether a combination of dietary CLA and soluble fibre would further decrease the proportion of body fat than a diet with CLA alone. Therefore, we fed mice diets with CLA and different amounts of Nutrim, containing 10% soluble fibre. CLA was added to the control diet at the expense of high oleic acid sunflower oil (HOSF) component and Nutrim was added at the expense of an isoenergetic combination of starch, dextrose and cellulose. The diets were fed for 28 days. Weight gain after 28 days was less in CLA-fed animals than in HOSF-fed animals. Both CLA and Nutrim increased the body water content. CLA reduced total body fat and epidydymal fat but Nutrim did not. No interaction of CLA and fibre was detected. We, therefore, must conclude that under the present experimental conditions dietary CLA and fibre do not interact to reduce body fat deposition.

The influence of dietary linoleic and alpha-linolenic acid on body composition and the activities of key enzymes of hepatic lipogenesis and fatty acid oxidation in mice.

We have recently suggested that feeding the C18 polyunsaturated fatty acid, alpha-linolenic acid (ALA), instead of linoleic acid (LA) reduced body fat in mice. However, the difference in body fat did not reach statistical significance, which prompted us to carry out this study using more animals and diets with higher contents of ALA and LA so that the contrast would be greater. The diets contained either 12% (w/w) LA and 3% ALA or 12% ALA and 4% LA. A low-fat diet was used as control. The diets were fed for 35 days. The proportion of body fat was not influenced by the type of dietary fatty acid. Plasma total cholesterol and phospholipids were significantly lower in ALA-fed mice than in mice fed LA. Activities of enzymes in the fatty acid oxidation pathway were significantly raised by these two diets when compared with the control diet. alpha-Linolenic acid vs. LA did not affect fatty acid oxidation enzymes. In mice fed the diet with LA activities of enzymes of de novo fatty acid synthesis were significantly decreased when compared with mice fed the control diet. alpha-Linolenic acid vs. LA feeding did not influence lipogenic enzymes. It is concluded that feeding mice for 35 days with diets either rich in LA or ALA did not significantly influence body composition.

Cholate and deoxycholate counteract the calcium-induced lowering of fat digestion in rats.

The objective of the present experiment was to investigate whether deoxycholate and cholate would differ in their effectiveness of counteracting the inhibitory effect of calcium on fat digestibility in rats. Rats were fed one of four experimental diets, a diet low in calcium, high in calcium or high in calcium with either 0.5% sodium cholate or 0.5% sodium deoxycholate. Both deoxycholate and cholate supplementation of the high-calcium diet reduced feed intake and body-weight gain. Low-calcium intake increased fat digestibility. Supplemental bile acids partially counteracted the calcium-induced inhibition of fat digestion, cholate being more effective than deoxycholate. The outcome is explained by the suggestion that cholate is bound to the calcium phosphate sediment in the small intestinal lumen with less affinity than deoxycholate. As a result, more cholate than deoxycholate would be available to support the process of fat digestion. Rats fed cholate had higher liver and serum cholesterol concentrations than did the rats fed deoxycholate.

Plasma lipids and fatty acid composition in parrots in relation to the intake of alpha-linolenic acid from two feed mixtures.

The main objective of this study was to find out whether the content of alpha-linolenic acid (ALA) in plasma cholesteryl-esters (CE) or triglycerides (TG) in parrots might serve as an index of ALA intake. The intake of ALA might be a risk factor for atherosclerosis, but on the basis of the fatty acid composition of seed mixtures the intake is difficult to assess due to selective eating of seeds. Parrots were fed two seed mixtures that differed in ALA content according to a cross over design. The macronutrient composition of the diets supplied differed from that of the diets consumed. The diets consumed had higher levels of dry matter, crude protein, crude fat and energy, and lower levels of crude fibre and crude ash. The ALA content, expressed as g/kg diet, was similar for the diet supplied and that consumed, irrespective of the type of diet. The diets had no systematic effect on plasma lipid concentrations. There were marked differences in plasma cholesterol concentrations between parrot species. When the diet with the low ALA content was fed (0.8% ALA of total fatty acids consumed, 1.1 g ALA/kg of diet consumed), the plasma CE and TG did not contain detectable ALA amounts. When the diet with the high ALA content was fed (4.2% ALA of total fatty acids consumed, 6.1 g ALA/kg of diet consumed), the plasma CE and TG contained about 1% ALA of total fatty acids. It is suggested that the content of ALA in plasma CE and TG might be used as an indicator of ALA intake.

Performance of trees in forest canopies: explorations with a bottom-up functional-structural plant growth model.

Here we present a functional-structural plant model that integrates the growth of metamers into a growing, three-dimensional tree structure, and study the effects of different constraints and strategies on tree performance in different canopies. The tree is a three-dimensional system of connected metamers, and growth is defined by the flush probability of metamers. Tree growth was simulated for different canopy light environments. The result suggest that: the constraints result in an exponential, logistic and decay phase; a mono-layered-leaf crown results from self-shading in a closed canopy; a strong apical control results in slender trees like tall stature species; the interaction between weak apical control and light response results in a crown architecture and performance known from short stature species in closed forest; correlated leaf traits explain interspecific differences in growth, survival and adult stature. The model successfully unravels the interaction effects of different constraints and strategies on tree growth in different canopy light environments.

Effect of sodium phytate supplementation on fat digestion and cholesterol metabolism in female rats.

The effects of sodium phytate supplementation on fat digestion and cholesterol metabolism were investigated in female rats. On the basis of an in vitro experiment showing that phytate raised the solubility of bile acids, it was predicted that phytate feeding would depress faecal bile acid excretion, raise apparent fat digestibility and elevate serum cholesterol concentrations. The experimental diets with or without sodium phytate were either cholesterol-free or cholesterol-rich and had a normal calcium concentration. Rats fed on the cholesterol-rich diet with sodium phytate showed enhanced faecal bile acid excretion, but there was no effect on fat digestibility. In rats fed the cholesterol-free diets, phytate did neither affect fat digestion nor bile acid excretion. Sodium phytate inclusion in the cholesterol-rich diet raised serum cholesterol concentrations, but reduced liver cholesterol concentration. Thus, the in vivo data do not agree with the in vitro observations. Both phytate and cholesterol feeding influenced mineral and trace element metabolism. Liver zinc concentrations were raised by phytate feeding. Cholesterol consumption reduced hepatic concentrations of copper, iron and zinc. Both phytate and cholesterol feeding reduced the apparent absorption of calcium, magnesium and phosphorus.

The effect of six different C18 fatty acids on body fat and energy metabolism in mice.

We studied the effects of five high-fat semi-purified diets varying at a 4% (w/w) level in either stearic, oleic, linoleic, alpha-linolenic, or gamma-linolenic acid on body fat and energy metabolism in BALB/c mice. A diet containing caprylic, capric, lauric, and myristic acid was used as a reference diet and a diet with 4% conjugated linoleic acid (CLA) was used as a positive control as it is known to effectively lower body fat in mice. The diets were fed for 35 d. Body fat was significantly lower in the CLA group than in the other groups but was not significantly different among the non-CLA groups. Among the non-CLA groups, the linoleic acid group tended to have the highest and the alpha-linolenic acid group the lowest proportion of body fat. In energy-balance studies, the percentage of energy intake that was stored in the body was significantly lower in the CLA group compared with the other dietary groups. The percentage of energy intake eliminated in excreta was highest in the stearic acid group followed by the gamma-linolenic acid group. These results were reflected in apparent fat digestibility, which was lowest in the stearic acid group. The percentage of energy intake expended as heat was highest in the CLA-fed mice. The results of the present study suggest that body fat and energy accretion in mice fed diets containing different C18 fatty acids is by far the lowest with CLA and that linoleic acid produced the highest fat intake and energy accretion.

Lowering dietary phosphorus concentrations reduces kidney calcification, but does not adversely affect growth, mineral metabolism, and bone development in growing rabbits.

New Zealand White rabbits were used to investigate the influence of increasing dietary P concentrations on growth performance, mineral balance, kidney calcification and bone development. The minimum dietary P requirement of 0.22 % (National Research Council) is usually exceeded in commercial natural-ingredient chows, leading to undesirable kidney calcifications. In order to study the optimal dietary P level, rabbits were fed semi-purified diets with four different P levels (0.1, 0.2, 0.4, and 0.8 %; w/w) at a constant dietary Ca concentration (0.5 %) during an 8-week period. Body weight and growth were not influenced by the dietary P level. During two periods (days 20-23 and 48-51), faeces and urine were collected quantitatively for the analysis of Ca, Mg and P and balances were calculated. Increased dietary P intake caused increased urinary and faecal P excretion and P apparent absorption and retention. Faecal Ca excretion increased with higher dietary P levels, whereas urinary Ca excretion reacted inversely. The apparent absorption of Ca became reduced at higher dietary P concentrations, but Ca retention was unchanged. The response of Mg was in a similar direction to that of the Ca balance. Kidney mineral content increased with higher dietary P levels, indicating the presence of calcified deposits. Nephrocalcinosis became more severe in kidney cortex and medulla at increasing dietary P levels, as was confirmed by histological analysis. Femur bone length was not differentially influenced by dietary P. Bone density (g/cm(3)) of the femur diaphysis became significantly lower at the 0.8 % dietary P level as compared with the 0.2 % P group only. The bone Mg content was significantly increased on the 0.8 % P diet, both in the diaphysis and epiphysis. Plasma P concentration increased and plasma Ca decreased with higher dietary P levels, whereas plasma Mg levels were unaffected. The present study shows that the current recommended minimum dietary P level of 0.2 % for rabbits, as advised by the National Research Council in 1977, leads to a normal growth and bone development, but also causes some degree of kidney calcifications at a dietary Ca level of 0.5 %. As the dietary P level of 0.1 % virtually prevented kidney calcification and at the same time did not give evidence for any deleterious effects on growth and bone development, this indicates that the current recommended dietary P level for rabbits should be regarded as a maximum advisable concentration, and that a lower P level may be more optimal.

Dietary conjugated linoleic acids as free fatty acids and triacylglycerols similarly affect body composition and energy balance in mice.

The objective of this study was to compare the effects of conjugated linoleic acid (CLA) as triacylglycerols (TAG) or free fatty acids (FFA) on body composition and energy balance in mice. We fed four groups of 5-wk-old Balb-C mice (n = 9) semipurified diets containing either CLA (0.5 g CLA/100 g of diet) or high oleic sunflower oil (HOSF) in the form of FFA or TAG for 42 d. Body composition was determined and the energy in the carcasses, excreta and food was measured in a bomb calorimeter. The amount of body fat was 4.72 +/- 0.95 g (17.9 +/- 2.8%) in the HOSF-FFA group, 2.36 +/- 0.29 g (9.4 +/- 1.0%) in the CLA-FFA mice (mean +/- SD, P < 0.05), 4.76 +/- 0.74 g (18.2 +/- 2.2%) in the HOSF-TAG group and 2.32 +/- 0.38 g (9.3 +/- 1.1%) in the CLA-TAG mice (P < 0.05). The percentage of energy intake that was stored in the body was 3.5 +/- 1.2% in the HOSF-FFA group, 0.6 +/- 0.3% in the CLA-FFA group (P < 0.05), 3.5 +/- 1.1% in the HOSF-TAG group and 0.5 +/- 0.4 in the CLA-TAG mice (P < 0.05). Conversely, the percentage of energy intake that was expended as heat was 89.4 +/- 1.2% in the HOSF-FFA group, 92.4 +/- 0.8% in the CLA-FFA mice (P < 0.05), 89.47 +/- 1.23% in the HOSF-TAG group and 92.2 +/- 0.4% in the CLA-TAG group (P < 0.05). Thus, CLA in the form of FFA or TAG had similar effects on body composition and energy balance.

Faecal bacterial profile, nitrogen excretion and mineral absorption in healthy dogs fed supplemental oligofructose.

In a cross-over trial, five healthy dogs were fed a dry food without or with 1% (w/w) oligofructose to assess any oligofructose-induced effects on the faecal bacterial profile, nitrogen excretion and mineral absorption. The diets were given for a period of 3 weeks. Oligofructose feeding significantly raised the number of Bifidobacteria, Streptococci and Clostridia in faeces. The numbers of faecal anaerobic and aerobic bacteria were raised after ingestion of oligofructose. The faecal pH was unchanged. There was no effect of oligofructose feeding on the route of nitrogen excretion which was associated with a lack of effect on faecal ammonium and urinary urea excretion. It is suggested that the absence or presence of an effect of oligofructose on urinary and faecal nitrogen excretion depends on the background composition of the diet, in particular the content of non-digestible, fermentable carbohydrates. In the diets used, the content of non-digestible, fermentable carbohydrates was not measured. Both apparent magnesium and calcium absorption were significantly raised by oligofructose feeding, but phosphorus absorption was unaffected. The data presented may contribute to the qualification of the use of oligofructose in dog foods.

Plasma lipid concentrations, macronutrient digestibility and mineral absorption in dogs fed a dry food containing medium-chain triglycerides.

In a cross-over trial with feeding periods of 2 weeks, six healthy dogs were fed a dry food with a total fat content of 13.4% and containing either 5% (w/w) corn oil (11% of dietary metabolizable energy) or an isoenergetic amount of medium-chain triglycerides (MCT). The two diets were supplied on a restricted basis. There were no food refusals and no diet difference in palatability was observed. The MCT vs. Corn oil did not significantly influence plasma lipid concentrations, but group mean triacylglycerol concentrations were increased by 23% (p=0.074). The MCT consumption did not affect the apparent digestibilities of crude protein and soluble carbohydrates and had no impact on the absorption of calcium, magnesium and phosphorus. The incorporation of MCT into the diet produced a slight increase (by 0.9 percentage units) in crude fat digestibility (p=0.061). It is concluded that MCT at the present inclusion level may not have disadvantageous effects.

Exercise- and metabolism-associated blood variables in Standardbreds fed either a low- or a high-fat diet.

Feeding a high-fat diet increases fat utilisation and may decrease glycogen utilisation resulting in a lower lactate production during moderate exercise. The effects of fat feeding on exercise- and lipid metabolism-associated blood variables were evaluated in 6 Standardbred horses during submaximal exercise. The horses were fed a high- (11.8% fat in total dietary dry matter) or a low-fat diet (1.5% fat) in a cross-over experiment with feeding periods of 4 weeks. At the end of each feeding period, the horses were subjected to a submaximal standardised stepwise exercise test on a treadmill. Blood samples were obtained prior to the start, during the last 10 s of each exercise step, and after recovery (40 min walking in hand). Pre-exercise test values for plasma lactate, pH, pCO2, ionised sodium, ionised potassium, ionised calcium, ionised chloride, glucose, nonesterified fatty acids and glycerol did not differ for the 2 diets. The pre-exercise concentration of triacylglycerols was significantly lower on the high- compared to the low-fat diet (mean +/- s.d. 0.17 +/- 0.06 and 0.23 +/- 0.08 mmol/l, respectively), whereas the concentrations of cholesterol (3.00 +/- 0.47 and 2.11 +/- 0.49 mmol/l, respectively), HDL cholesterol (1.80 +/- 0.18 and 1.35 +/- 0.27 mmol/l, respectively) and phospholipids (2.30 +/- 0.11 and 1.72 +/- 0.20 mmol/l, respectively) were significantly higher. There was significantly less plasma lactate accumulation during exercise when the horses were given the high-fat diet (P = 0.011). Horses on a low-fat diet had significantly different plasma lipid values when compared to being on a high-fat diet. The alterations in these values during and after moderate exercise were comparable for both diets. These results indicate that fat metabolism is significantly adapted on a high-fat diet; feeding such a diet may enhance potential performance by delaying lactate accumulation and thereby delaying the onset of fatigue.

Environmental pollution in the Gulf of Guinea--a regional approach.

Environmental pollution in the Gulf of Guinea (GOG) coastal zone has caused eutrophication and oxygen depletion in the lagoon systems, particularly around the urban centres, resulting in decreased fish (reproduction) levels and waterborne diseases. A pollution sources assessment was undertaken by six countries in the region as a first step in defining a region-wide Environmental Management Plan. Results show that households produce 90% of solid waste. Industry, however, is responsible for substantial amounts of hazardous waste, specifically the Nigerian petroleum industry. The latter is also responsible for the spilling of large amounts of oil. BOD load from industrial effluents is slightly larger than domestic loads in the industrialised coastal zone. Wastewater treatment systems are either absent or inadequate. Apart from large-scale gas flaring in Nigeria, air pollution, in terms of COx, HC, NOx and SO2 emissions, is contributed mainly by traffic. Particulates, originate mainly from industries and domestic biomass burning.

Cholate feeding counteracts calcium-induced depression of apparent fat digestibility in rats.

This study tested the hypothesis that cholate feeding would counteract the earlier described calcium-induced inhibition of fat digestion. Rats were fed semipurified diets; either low (0.25%, w/w) or high (1.0%) in calcium, the latter diets being without or with 0.5% added sodium cholate. Apparent fat digestibility was 95.6% of intake in the rats fed the low-calcium diet. Calcium feeding significantly lowered apparent fat digestibility to 82.6%, but in the presence of cholate it was 91.2%. It is concluded that the inhibitory effect of calcium on fat digestion is mediated by diminishing the availability of bile acids.

High density lipoprotein cholesteryl ester metabolism in the pony, an animal species without plasma cholesteryl ester transfer protein activity: transfer of high density lipoprotein cholesteryl esters to lower density lipoproteins and the effect of the amount of fat in the diet.

The metabolism of high density lipoprotein cholesteryl esters (HDL CE) was studied in the pony, an animal species without plasma cholesteryl ester transfer protein (CETP) activity. Studies were done in ponies fed a low- (1.5% fat, w/w) and a high-fat diet (11.5%, w/w fat). The ponies fed the high-fat diet had higher plasma HDL CE concentrations (1.08+/-0.15 vs. 0.84+/-0.11 mmol/l, mean+/-S.D., n=6, P<0.01) and plasma lipoprotein lipase (LPL) activities (14.3+/-4.0 vs. 5.7+/-3.4 micromol free fatty acids (FFA)/ml per h, P<0.05) than those on the low-fat diet. Plasma triacylglycerol (TAG) concentrations were lower on the high-fat diets (0.129+/-0.043 vs. 0.180+/-0.050 mmol/l), but these differences were not statistically significant. There was a negative correlation between the levels of plasma TAG (r=0.598, P<0.05) and VLDL CE (r=0.658, P<0.05) on the one hand and the HDL CE concentrations on the other hand. The transport rates of HDL CE were not significantly different between ponies fed high-fat (0.029+/-0.008 mmol HDL CE/h per l plasma) and those fed low-fat diets (0.024+/-0.004). HDL CE were transferred to low density lipoproteins (LDL) and we calculated that the percentage of LDL CE derived from HDL was 0.69+/-0.13 in the ponies fed the low-fat diet and 0.53+/-0.05 in the ponies fed the high-fat diet (P<0.05). The results of these in vivo studies suggest that in ponies, similarly as reported in rats and pigs, HDL CE can be transferred to LDL despite the absence of plasma CETP activity, and that the magnitude of this transfer is related to the levels of HDL CE as induced by the amount of fat in the diet.

A comparative study of iron retention in mynahs, doves and rats.

Iron retention was studied in rats (Rattus norvegicus), doves (Streptopelia d. decaocto) and two species of mynahs (Acridotheres t. tristis and Gracula r. religiosa) fed two different pelleted diets (88.5 and 567.9mg Fe/kg diet). The doves and rats served as species that are not susceptible to iron storage, whereas the mynahs are known to develop iron overload frequently. The retention was calculated after measuring the uptake and elimination of a single dose of radioactive iron ((59)Fe) using whole-body counting. It was hypothesized that the mynahs would retain more iron than the rats and doves, and that after dietary iron challenge the mynahs would downregulate iron retention less effectively. It is concluded that mynahs have much higher iron uptake and retention than doves, but a similar uptake to that in rats. The four studied species are able to downregulate iron retention, the doves being the most efficient. It is suggested that at least part of the susceptibility to iron overload in mynahs is related to a high iron absorption from the intestines regardless of body iron stores, which is comparable with the situation of hereditary haemochromatosis in man.

Dietary polyunsaturated fatty acids and plasma butyrylcholinesterase activity in piglets.

Diets containing different ratios of n-3:n-6 polyunsaturated fatty acids, were fed to piglets for a period of 10 days. Diets with n-3:n-6 ratios of 0.2 and 0.3 decreased the group mean activity of plasma butyrylcholinesterase when compared with a diet with a ratio of 0.1.

Usefulness of immunochromatographic detection of antibodies to Mycobacterium tuberculosis as an adjunct to auramine staining for rapid diagnosis of tuberculosis in a low-prevalence setting.

A novel immunochromatographic membrane-based assay for the detection of specific IgG antibodies to Mycobacterium tuberculosis was evaluated in patients with active tuberculosis in a low-prevalence population. The sensitivity of the test for detecting active tuberculosis was 41.5% (17/41 patients positive); its specificity in a group of patients with other lung diseases was 91.4% (3/35 false positive), while in a group of 47 healthy controls it was 100%. The sensitivity of the immunochromatographic test equaled that of auramine staining, but different subsets of tuberculosis patients were detected by the two tests. The suboptimal sensitivity of this immunochromatographic test implies that, even though it could be a useful adjunct, it cannot be a replacement for the diagnosis of tuberculosis by other microbiological methods along with clinical and radiological data.

Indomethacin for 3 days is not effective as prophylaxis for heterotopic ossification after primary total hip arthroplasty.

Although indomethacin is effective in preventing heterotopic ossification (HO) after total hip arthroplasty (THA) when used for 8 to 14 days, side effects are frequently observed. We conducted a prospective, nonrandomized pilot study of prophylaxis for HO in THA using indomethacin for 3 days. We used a 2-stage design for phase 2 clinical data, based on earlier studies in our department. Our study group consisted of 19 patients, of whom 14 (74%) developed HO; 7 (37%) showed grade 1, 4 (21%) grade II, and 3 (15.8%) grade III according to the Brooker classification. We compared these results with 2 historic control groups; one group received indomethacin for 7 days, and the other group received no prophylaxis. We did not see any reduction of the ossification relative to the group that received no prophylaxis. Indomethacin for 3 days seems not to be sufficient to prevent HO.