Göran Nilsson

Effects of Organic Fertilizers and Urea when Applied to Spring Wheat

Abstract Ecologically or organically produced wheat often has a protein content that is too low to be successfully used in modern bakeries. To increase the protein content in spring wheat, two organic fertilizers (slurry manure and meat bone meal) were compared with urea in field trials. Mycological analyses were performed to study whether any mould infection occurred. Protein content was increased by the organic fertilizers to a level about the same as given by the urea treatment. Slurry manure exhibited a lower effect per kg applied N than urea and meat bone meal. The results indicate that no consistent differences in endogenic mould infection were present between treatments. Meat bone meal can be used as a supplement at growth stage 30–31 to increase the protein content. Slurry manure has to be applied at high rates at sowing to get a pronounced effect on protein content and yield.

Inhibition of acid formation and stimulation of somatostatin release by cholecystokinin-related peptides in rabbit gastric glands

1. The purpose of the present study was to investigate the role of somatostatin in the inhibition of acid production induced by caerulein and cholecystokinin (CCK) in isolated rabbit gastric glands. Acid production was estimated by the aminopyrine technique. 2. Exogenous somatostatin 14 and somatostatin 28 (10(‐7) M) reduced to a similar extent the aminopyrine uptake produced by 5 x 10(‐5) M‐histamine during the course of 40 min incubation. 3. Significant inhibition of histamine‐stimulated aminopyrine accumulation occurred at a somatostatin 14 concentration of 10(‐9) M. 4. Caerulein and CCK octapeptide (10(‐13)‐10(‐7) M) were found to release somatostatin from isolated gastric glands in a dose‐dependent manner. The dose‐response relationships for somatostatin release and inhibition of aminopyrine uptake were similar. Thus, the half‐maximal dose approximations for somatostatin release and inhibition of aminopyrine uptake were 0.5 and 1.4 x 10(‐9) M respectively for CCK octapeptide and 0.9 and 2.5 x 10(‐11) M for caerulein. Heptadecapeptide gastrin proved to be a very poor releaser of somatostatin in the system used. The CCK octapeptide‐induced somatostatin release was time dependent and the concentrations of somatostatin that accumulated in the incubation medium were similar to those of exogenous somatostatin that were needed to evoke inhibition. 5. The present results support the concept that cholecystokinin inhibits gastric acid secretion by releasing somatostatin from endocrine‐like cells in the gastric mucosa. It is suggested that cholecystokinin‐related peptides may play a physiological role in inhibiting gastric acid secretion. A similar role for gastrin is not supported by the present study.

Effects of cholecystokinin on acid formation in glands and cells isolated from rabbit and rat gastric mucosa

Isolated gastric glands and isolated cells prepared from rabbit and rat were studied to analyse the influence of cholecystokinin octapeptide (CCK 8) on histamine stimulated parietal cell acid formation as assessed by [14C]aminopyrine sequestered in acid tissue compartments. In rabbit gastric glands, CCK 8 evoked 32+/-6% (P<0. 01) inhibition of histamine stimulated acid formation, whereas in glands prepared from rat no inhibition was recorded. Instead, CCK 8 seemed to induce a variable increase of the histamine stimulation in rat gastric glands as the aminopyrine accumulation was increased by 110+/-46% (P<0.1). Further studies on cell preparations derived from rabbit gastric mucosa revealed dual properties of CCK 8, eliciting either inhibition or stimulation of the parietal cell depending on the presence of endocrine cells. The results show that paracrine communication may be effective in glandular preparations, but seems to vary depending on species.

Cholecystokinin and Gastrin Inhibit Histamine Stimulated Aminopyrine Uptake in Isolated Rabbit Gastric Glands

In the present study we have analyzed if cholecystokinin (CCK) or gastrin (G) can inhibit acid production in isolated rabbit gastric glands as revealed by the aminopyrine technique. The results show that G 17 I, CCK 8 NS, CCK 8 S, ceruletide and CCK 39 significantly inhibit histamine induced aminopyrine accumulation. No significant inhibition was noted for G 4, G 34 and NT G 1-13. As a group the CCK peptides were more effective than the gastrin peptides in inhibiting the aminopyrine uptake. CCK 8 S and ceruletide, the most potent inhibitors, reduced histamine induced aminopyrine accumulation with an ED50 of 10(-9) and 10(-10) M respectively. These potencies are similar to those by which CCK peptides stimulate isolated pancreatic acini to secrete amylase. Inhibition evoked by CCK 8 S was most effective following 20-40 min of incubation time, possibly indicating that the effect is mediated by the release of an intermediate substance. The results may therefore indicate a role for cholecystokinin as a physiological inhibitor of acid secretion in the rabbit. The results may also contribute to explain why the potent gastric secretagogue gastrin per se fails to stimulate acid formation in gastric glands isolated from the rabbit.