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Background & aims Only a fraction of IBS patients show increased perceptual sensitivity to rectal distension, suggesting possible differences in processing and/or modulation of visceral afferent signals within this group. The aim was to identify brain mechanisms which may underlie these perceptual differences. Methods 44 women with IBS and 20 female healthy control subjects (HCs) were included. Symptom severity in IBS was determined by Severity Scoring System (IBS-SSS). Anxiety and depression symptoms were assessed using the Hospital anxiety & depression score (HAD). Blood oxygen level dependent (BOLD) signals were measured by functional Magnetic Resonance Imaging (fMRI) during expectation and delivery of high (45mmHg) and low (15mmHg) intensity rectal distensions. Perception thresholds to rectal distension were determined in the scanner. Brain imaging data from 18 normosensitive, 15 hypersensitive IBS patients and 18 HCs were compared. Results were reported significant if peak p-value ≤ 0.05 with family wise error correction in regions of interest. Results The two IBS subgroups were similar in age, symptom duration, psychological symptoms and IBS symptom severity. While brain responses to distension were similar in normosensitive patients and HCs, hypersensitive IBS demonstrated greater activation of insula and reduced deactivation in pregenual anterior cingulate cortex during noxious rectal distensions, compared to both HCs and normosensitive IBS. During expectation of rectal distension, normosensitive IBS had more activation in right hippocampus than HCs. Conclusions Despite similarities in symptoms, hyper- and normosensitive IBS patients differed substantially in cerebral response to standardized rectal distensions and their expectation, consistent with differences in ascending visceral afferent input.

A, 1984, Ammonium uptake in Lemna gibba G 1, related membrane potential changes, and inhibition of anion uptake, -Physiol, Plant, 61;[369][370][371][372][373][374][375][376] In N-starved (-N) fronds oi Lemna gibba L, G 1, NHJ uptake rates were several-fold those of NOi-supplied ( + N) fronds, NOj uptake in +N-plant,s was slow and not inhibited by addition of NHJ, However, in-N-plants with higher NO^ and still higher NH| uptake rates, addition of NH| immediately reduced the NO5 uptake rates to about one third until the NHJ was consumed. The membrane potential (E,,,) decreased immediately upon addition of NH4+ in all fronds, but whereas depolarisation was moderate and transient in -t-N-plants, it was strong, up to 150 mV, in N-starved plants, where E,,, remained at the level of the K' diffusion potential (Ep) until NHJ was removed. In N-starved plants NHJ uptake and membrane depolarisation showed the same concentration dependence, except for an apparent linear component for uptake. Phosphate uptake was inhibited by NH4+ similarly to NO5 uptake, but only in P-and N-starved plants, not after mere P starvation. Influx of NO5 and H:PO4 into the negatively eharged cells of Lemna is mediated by anion/H* cotransport, but NH4+ influx can follow the electrochemical gradient. Its saturating component may reflect a carrier-mediated NHJ uniport, the linear component diffusion of NH4+ or NH,, Inhibition of anion/H+ eotransport by high NH4+ influx rates may be due to loss of the proton-driving force, AflH% across the plasmalemma. Reversible inhibition by NHJ of the H+ extrusion pump may contribute to the finding that A|:iH+ cannot be reconstituted in the presence of higher NHJ concentrations.Additional key words -H+ extrusion pump, nitrate uptake, phosphate uptake, W. R. Ullrich (reprint requests) and S. Lesch, Insl. fiir Boianik, Teclmische Hochschule, Sclmittspahnstras.se 3, FRG; M, Botaniska In.st., Stocklwlms Univ., Sweden; A. Novacky,

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In the current study, colorectal distension (CRD) was performed in conscious mice, in order to study visceral (colon) sensitivity. Electrodes were chronically implanted into the external oblique muscle to obtain the electromyographic (EMG) response to CRD. CRD was performed using a computerized system, which inflated the balloon with air to the desired pressures. An increasing (10-80 mmHg) and a repeated (12 x 55 mmHg) phasic paradigm with distensions lasting 10 s and with 5-min intervals were used. The EMG recordings were linearly correlated to intracolonic pressures between 10 and 80 mmHg, which are characteristic of the visceromotor response (VMR). Repeated phasic distensions at 55 mmHg resulted in a stable VMR in female mice, but an increasing VMR in male mice. Interestingly, the duration of the VMR was about 5 s, which is shorter than the actual duration of the distension. U-69593 and fentanyl (selective kappa and mu opioid receptor agonists) significantly reduced the VMR at subcutaneous doses of 0.5 and 0.05 mg x kg-1, respectively. In conclusion, a CRD model for repetitive quantitative studies of colorectal sensitivity and evaluation of pharmacological modulation of visceral sensitivity in conscious mice is presented.

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The absorption of Zn or Fe from breakfast meals containing oat porridge prepared from malted and soaked oats and a control porridge made from untreated oats was measured in human subjects. The effect on Zn and Fe absorption of reducing the phytate content of oat-porridge meals was examined in each subject by extrinsic labelling of porridge with 6bZn and of bread rolls with 56Fe and 59Fe, and measuring whole-body retention and the erythrocyte uptake of isotopes. Each experiment comprised nine to ten subjects. The absorption of Zn from mdted-oat porridge with a phytate (inositol hexaphosphate) content of 107 pmol was 18.3 YO, and significantly higher (P < 0-05) than from the control porridge containing 432 p o l phytate (11.8 Yo). Fe absorption from the meal containing malted-oat porridge with 107 p o l phytate (Expt 2) was also significantly improved (P < 0.05) compared with that from the meal containing control porridge with 437 p o l phytate. The average increase in Fe absorption was 47 %, or from 4.4 to 60%. In the breakfast meal containing malted porridge with 198 pmol phytate (Expt 3) the increase in Fe absorption was not significantly improved. Even though the phytate content was reduced to a greater extent in Expt 3 than Expt 2, the average increase in Fe absorption in Expt 3 was only 25 70 more than that from the meal containing control porridge (with 599 p o l phytate), depending on the higher absolute amount of phytate. In conclusion, an improvement in Zn and Fe absorption from oat products can be achieved by practising malting and soaking in the processing of oats. This may be of importance in the prevention of mineral deficiency in vulnerable groups. Zinc: Iron: Phytate: Oats Oats are considered to be a nutritious cereal grain and new applications and oat products are frequently developed. However, mineral availability can be impaired at high intakes of oat products owing to the presence of high concentrations of phytate (inositol hexaphosphate; IP-6). Rossander et al. (1990) studied the inhibitory effects of oat products on non-haem-Fe absorption in human subjects from single meals and found that oat bran and oat porridge markedly inhibited Fe absorption. The effect on Fe stores in young, healthy subjects after dietary changes from a diet with a relatively high fat and low fibre content to a low-fat, high-fibre and high-phytate diet was investigated in a long-term study by Sandstrom (1993). It was found that the ferritin levels in blood were reduced during the 8-month dietary change. The absorption of Zn from single meals based on rye, oatmeal, barley, triticale and whole wheat was also evaluated , and the lowest Zn absorption was observed from oatmeal porridge (8.4 %), which also contained the highest amounts of phytate. Sandstrom et al. (1987) concluded that when phytate-rich cereals constitute a major part of the total Zn intake of a diet, processes that reduce the M. L A R S S O N A N D OTHERSphytate content could significantly improve the absorption of Zn. The high content of phytate combined...

TO reduce phytate in oat products and thereby increase mineral bioavailability, optimal conditions for phytate degradation in oats were investigated. The effects of malting and incubation on phytate reduction in oats were determined and compared with phytate degradation in wheat, rye and barley. Studies of incubation temperatures showed an optimum for phytate reduction in oats between 37-4O"C which differed from that in wheat (55°C). Malting of oats for 5 days at 11°C and subsequent incubation for 17 hr at 37-4O"C reduced phytate by 98%. Addition of malted rye also reduced the phytate content of oats to low levels.